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An Innovative Approach to Wind Strengthening of a Cantilevered Stadium Roof, Yarrows Stadium, Taranaki

C. Twaddle and R. Van Bergen

Beca Ltd, New Zealand Fitzroy Engineering Group Limited

New Plymouth District Council ABSTRACT: This case study outlines the assessment and innovative retrofit of a large cantilevered stadium roof at Yarrows Stadium, New Plymouth, Taranaki that sustained significant wind related damage in a high wind event in 2012. The stadium roof sustained damage to a significant area of roofing due to a roof fixing failure. However the investigation highlighted a significant change in the wind loading standard associated with cantilevered roofs. Through agreement with the then owner, the New Plymouth District Council (NPDC), a roof structure review by Beca was initiated. The review identified that the stadium stand structure, constructed in 2001 had been designed and built prior to the current versions of AS/NZS1170.2 where cantilevered roofs are specifically covered. The upward wind loading of the truss imposed the most significant load in this case where the existing (steel circular hollow section) top chord was subjected to a significant compressive axial load that exceeded the capacity of the member. This risked structural failure at what is considered a wind event with a serviceability probability of exceedance. This meant that the stadium roof structure was subject to a relative risk of failure of 10 to 20 times that of a new roof structure of the same form. This can be considered similar to the relative risk associated with an earthquake prone building. While there is no provision in the building act for retrofitting structures for wind loading, the recent changes to the wind loading standards are specific and significant. Given the level of relative risk and the number of potential affected parties, the NPDC commissioned Beca to design a retrofit to mitigate this risk. A logical retrofit for this roof involved providing a restraint at the middle of the top chord of the truss, with suitable load paths to transfer restraint loads into existing load paths. This would stabilize the strut and protect it from an axial buckling failure. The issues with such a solution that governed the design were: safety, access, environmental issues and work quality. The roof was 14m above ground level making access difficult and risky. The existing roofing system was underslung with fixings that failed under pedestrian/service loading (therefore access was limited to the purlin structure only, at 2.5m centers). The areas of works were exposed to all elements being exterior in nature. The expense and associated risks (safety, works length, quality and cost) of the works suggested an alternative solution that allowed for prefabrication and simple site assembly. The retrofit included:

• A bespoke multifunctional innovative steel clamp that accommodated multiple members and alignments;

• It could be fabricated offsite and site fitted directly off a bespoke lifting plate assembly; • Access was via Mobile crane lifted work platforms; • A single member type and connection detail to be used for the entire strengthening works. • Tactical use of friction grip bolts to facilitate rapid construction with site tolerance.

The retrofit allowed: • Minimizing exposure of contractors to site risks such as height, weather and access. • Improving the quality of the product by offsite fabrication. • Improving the efficiency of all parties onsite including the ultimate cost of the retrofit.

The retrofit design was initially conceived in house and then collaboratively developed further with both the client and the contractor, Fitzroy Engineering Group limited (FEGL). Ultimately, the successful design and collaboration of all parties allowed the installation of 4 tons of structural steel on top of a relatively inaccessible stadium in three and a half working days.

1. BACK GROUND:

Beca Infrastructure Ltd (Beca) was commissioned by New Plymouth District Council (NPDC) following the failure of roof sheeting on the TSB Stand Roof at Yarrow Stadium, which occurred April 2012. The scope of our initial engagement was to investigate the cause of failure and assist NPDC to make appropriate repairs that would allow the stadium to be used for events.As this commission evolved it became evident that

• •

• Yarrow Stadiusporting events, predominantly rugby. It seats approximately 26,000 people with the majority of spectators in the two main stands, the TSB Stand and the Yarrows Stand. and West sides of the main sports field respectively, which is aligned approximately North to South.to Figure 1 below for a site aerial photo.

The TSB Stand (and Yarrows stand), the subject of strengthening was constructed in 2001 in its current form. (TRC)established 2. EXISTING STADIUM STA

The steel roof structure above the top floor level on both stands consists of heavy steel columns that form a portal frame with a steel truss, which cantilevers 21m over the bleachers towards the main field. The steel tsection (UB) as the bottom chord located immediately above the underslung roof, consisting of profiled aluminum roofing supported below steel rectangular holstand is in the order of 3,000m

YarrowsStand

BACK GROUND:


Its structural condition. Capacity of the existing roof structure to resist wind loads relative to the current wind loadings

standard Consider

Yarrow Stadium issporting events, predominantly rugby. It seats approximately 26,000 people with the majority of spectators in the two main stands, the TSB Stand and the Yarrows Stand. and West sides of the main sports field respectively, which is aligned approximately North to South.to Figure 1 below for a site aerial photo.

The TSB Stand (and Yarrows stand), the subject of strengthening was constructed in 2001 in its current form. Since July 2013, t(TRC) and NPDCestablished (comprising T

EXISTING STADIUM STA

The steel roof structure above the top floor level on both stands consists of heavy steel columns that form a portal frame with a steel truss, which cantilevers 21m over the bleachers towards the main field. The steel truss (7.3m centres) is constructed from circular hollow sections (CHS) with a steel universal beam section (UB) as the bottom chord located immediately above the underslung roof, consisting of profiled aluminum roofing supported below steel rectangular holstand is in the order of 3,000m

Yarrows Stand

BACK GROUND:


Its structural condition.apacity of the existing roof structure to resist wind loads relative to the current wind loadings

standard. onsideration of

m is located near the CBD of New Plymouth and issporting events, predominantly rugby. It seats approximately 26,000 people with the majority of spectators in the two main stands, the TSB Stand and the Yarrows Stand. and West sides of the main sports field respectively, which is aligned approximately North to South.to Figure 1 below for a site aerial photo.

The TSB Stand (and Yarrows stand), the subject of strengthening was constructed in 2001 in its current Since July 2013, tand NPDC, with Management and

(comprising T


The steel roof structure above the top floor level on both stands consists of heavy steel columns that form a portal frame with a steel truss, which cantilevers 21m over the bleachers towards the main field. The

russ (7.3m centres) is constructed from circular hollow sections (CHS) with a steel universal beam section (UB) as the bottom chord located immediately above the underslung roof, consisting of profiled aluminum roofing supported below steel rectangular holstand is in the order of 3,000m

BACK GROUND:


Its structural condition. apacity of the existing roof structure to resist wind loads relative to the current wind loadings

ation of serviceability issues relating to the TSB stand.located near the CBD of New Plymouth and is

sporting events, predominantly rugby. It seats approximately 26,000 people with the majority of spectators in the two main stands, the TSB Stand and the Yarrows Stand. and West sides of the main sports field respectively, which is aligned approximately North to South.to Figure 1 below for a site aerial photo.

The TSB Stand (and Yarrows stand), the subject of strengthening was constructed in 2001 in its current Since July 2013, the ownership of the stadium

, with Management and (comprising TRC and NPDC)



russ (7.3m centres) is constructed from circular hollow sections (CHS) with a steel universal beam section (UB) as the bottom chord located immediately above the underslung roof, consisting of profiled aluminum roofing supported below steel rectangular holstand is in the order of 3,000m2.


apacity of the existing roof structure to resist wind loads relative to the current wind loadings

serviceability issues relating to the TSB stand.located near the CBD of New Plymouth and is

sporting events, predominantly rugby. It seats approximately 26,000 people with the majority of spectators in the two main stands, the TSB Stand and the Yarrows Stand. and West sides of the main sports field respectively, which is aligned approximately North to South.to Figure 1 below for a site aerial photo.

Figure 1 The TSB Stand (and Yarrows stand), the subject of strengthening was constructed in 2001 in its current

he ownership of the stadium , with Management and

RC and NPDC)

EXISTING STADIUM STAND DESCRIPTION:


russ (7.3m centres) is constructed from circular hollow sections (CHS) with a steel universal beam section (UB) as the bottom chord located immediately above the underslung roof, consisting of profiled aluminum roofing supported below steel rectangular hol




sporting events, predominantly rugby. It seats approximately 26,000 people with the majority of spectators in the two main stands, the TSB Stand and the Yarrows Stand. and West sides of the main sports field respectively, which is aligned approximately North to South.

Figure 1 – Plan of Yarrows The TSB Stand (and Yarrows stand), the subject of strengthening was constructed in 2001 in its current

he ownership of the stadium , with Management and Operations undertaken by the NPDC.

RC and NPDC) to provide overall gove

ND DESCRIPTION:


russ (7.3m centres) is constructed from circular hollow sections (CHS) with a steel universal beam section (UB) as the bottom chord located immediately above the underslung roof, consisting of profiled aluminum roofing supported below steel rectangular hol

Beca Infrastructure Ltd (Beca) was commissioned by New Plymouth District Council (NPDC) following the failure of roof sheeting on the TSB Stand Roof at Yarrow Stadium, which occurred April 2012. The scope of our initial engagement was to investigate the cause of failure and assist NPDC to make appropriate repairs that would allow the stadium to be used for events.As this commission evolved it became evident that assessment




Plan of Yarrows The TSB Stand (and Yarrows stand), the subject of strengthening was constructed in 2001 in its current

he ownership of the stadium has residedperations undertaken by the NPDC.

to provide overall gove

ND DESCRIPTION:


russ (7.3m centres) is constructed from circular hollow sections (CHS) with a steel universal beam section (UB) as the bottom chord located immediately above the underslung roof, consisting of profiled aluminum roofing supported below steel rectangular hollow sections (RHS). The total roofed area of each

Beca Infrastructure Ltd (Beca) was commissioned by New Plymouth District Council (NPDC) following the failure of roof sheeting on the TSB Stand Roof at Yarrow Stadium, which occurred April 2012. The scope of our initial engagement was to investigate the cause of failure and assist NPDC to make appropriate repairs that would allow the stadium to be used for events.

assessment was required


serviceability issues relating to the TSB stand.located near the CBD of New Plymouth and is a sports venue catering for top level


Plan of Yarrows StadiumThe TSB Stand (and Yarrows stand), the subject of strengthening was constructed in 2001 in its current

has resided perations undertaken by the NPDC.

to provide overall governance

ND DESCRIPTION:


russ (7.3m centres) is constructed from circular hollow sections (CHS) with a steel universal beam section (UB) as the bottom chord located immediately above the underslung roof, consisting of profiled

low sections (RHS). The total roofed area of each

Beca Infrastructure Ltd (Beca) was commissioned by New Plymouth District Council (NPDC) following the failure of roof sheeting on the TSB Stand Roof at Yarrow Stadium, which occurred April 2012. The scope of our initial engagement was to investigate the cause of failure and assist NPDC to make appropriate repairs that would allow the stadium to be used for events.

was required of


serviceability issues relating to the TSB stand. a sports venue catering for top level

sporting events, predominantly rugby. It seats approximately 26,000 people with the majority of spectators in the two main stands, the TSB Stand and the Yarrows Stand. These are located on the East and West sides of the main sports field respectively, which is aligned approximately North to South.

Stadium The TSB Stand (and Yarrows stand), the subject of strengthening was constructed in 2001 in its current

with the Taranaki Regional Council perations undertaken by the NPDC.

ance and a joint vision




Beca Infrastructure Ltd (Beca) was commissioned by New Plymouth District Council (NPDC) following the failure of roof sheeting on the TSB Stand Roof at Yarrow Stadium, which occurred during high winds in April 2012. The scope of our initial engagement was to investigate the cause of failure and assist NPDC to make appropriate repairs that would allow the stadium to be used for events.

of the following


a sports venue catering for top level sporting events, predominantly rugby. It seats approximately 26,000 people with the majority of

These are located on the East and West sides of the main sports field respectively, which is aligned approximately North to South.

The TSB Stand (and Yarrows stand), the subject of strengthening was constructed in 2001 in its current the Taranaki Regional Council

perations undertaken by the NPDC. A Jointand a joint vision




Beca Infrastructure Ltd (Beca) was commissioned by New Plymouth District Council (NPDC) following the during high winds in

April 2012. The scope of our initial engagement was to investigate the cause of failure and assist NPDC

the following:



These are located on the East and West sides of the main sports field respectively, which is aligned approximately North to South.


A Joint committee was and a joint vision.




TSB Stand

North





These are located on the East and West sides of the main sports field respectively, which is aligned approximately North to South. Refer


committee was




TSB Stand

North





These are located on the East Refer


committee was




TSB Stand

For the purposes of discussion in later sections, the critical sections of the roof steel structure are identified in The entire TSB Stand structure is supported on piles as it is sited near to the middle of the original fill zone of the valley. This three storey structure has a double height middle storey. The ground floor contains thmembers area, known as the Legends Lounge. The lateral resisting structure consists of a braced steel structure, with both eccentrically (Kdirection and steel moment resisting frames in the easton raking steel beams and the suspended floors are generally constructed from hollowcore precast concrete units with an inFigure

3. HIGH WIND DAMAGE: In March west which loaded the underslungheld the roofing to the underside of the RHS purlins.The damage occurred on the SW tip of the TSB Stand and covered an area of 90 to 120mFigure 3 above for an annotatioDuring the subseqfor damage, it was raised to cantilever roofs hafor the to establish whether the structure was exposed to hiunderstood and to then be able to manage that risk in an informed manner. This wind structural assessment, the findings and associated implementation is the subject of this paper.

4. ROOF ASSESSMENT:

Wind The structure was designed under NZS4203:1992, which does not specifically cover large cantilevered roofs. However an assumed basis for design was likely derived from one of the existing similar cases within the standard such as for an exposed roThe Australian wind loading standard, AS1170.2 cantilevered roofs in roofs by coefficients around these types of structures were notably higher than had been previously assumed.In 2004, New Zealand and Australia combined

Transverse Strengthening plane

For the purposes of discussion in later sections, the critical sections of the roof steel structure are identified in Figure The entire TSB Stand structure is supported on piles as it is sited near to the middle of the original fill zone of the valley. This three storey structure has a double height middle storey. The ground floor contains the sports facilities, the first floor contains the public concourse and the top floor contains the members area, known as the Legends Lounge. The lateral resisting structure consists of a braced steel structure, with both eccentrically (Kdirection and steel moment resisting frames in the easton raking steel beams and the suspended floors are generally constructed from hollowcore precast

rete units with an inFigure 2.

HIGH WIND DAMAGE:

March 2012, the TSB Stand suffered high wind related damage from a gust event(s) from the south est which loaded the underslung

held the roofing to the underside of the RHS purlins.The damage occurred on the SW tip of the TSB Stand and covered an area of 90 to 120mFigure 3 above for an annotatioDuring the subseqfor damage, it was raised to cantilever roofs hafor the stadium was extended to allow assessment of the primary structure as wellto establish whether the structure was exposed to hiunderstood and to then be able to manage that risk in an informed manner. This wind structural assessment, the findings and associated implementation is the subject of this paper.

ROOF ASSESSMENT:

Wind Loading The structure was designed under NZS4203:1992, which does not specifically cover large cantilevered roofs. However an assumed basis for design was likely derived from one of the existing similar cases within the standard such as for an exposed roThe Australian wind loading standard, AS1170.2 cantilevered roofs in roofs by Melbourne and Cheung coefficients around these types of structures were notably higher than had been previously assumed.In 2004, New Zealand and Australia combined

Transverse Strengthening

For the purposes of discussion in later sections, the critical sections of the roof steel structure are Figure 2. The same terms apply when discussing the

The entire TSB Stand structure is supported on piles as it is sited near to the middle of the original fill zone of the valley. This three storey structure has a double height middle storey. The ground floor

e sports facilities, the first floor contains the public concourse and the top floor contains the members area, known as the Legends Lounge. The lateral resisting structure consists of a braced steel structure, with both eccentrically (Kdirection and steel moment resisting frames in the easton raking steel beams and the suspended floors are generally constructed from hollowcore precast

rete units with an in

Figure 2 & 3

HIGH WIND DAMAGE:

2012, the TSB Stand suffered high wind related damage from a gust event(s) from the south est which loaded the underslung

held the roofing to the underside of the RHS purlins.The damage occurred on the SW tip of the TSB Stand and covered an area of 90 to 120mFigure 3 above for an annotatioDuring the subsequent investigation of the roof claddingfor damage, it was raised to cantilever roofs had changed since the design of the original structure. Therefore the engineering

stadium was extended to allow assessment of the primary structure as wellto establish whether the structure was exposed to hiunderstood and to then be able to manage that risk in an informed manner. This wind structural assessment, the findings and associated implementation is the subject of this paper.

ROOF ASSESSMENT:

oading StandardsThe structure was designed under NZS4203:1992, which does not specifically cover large cantilevered roofs. However an assumed basis for design was likely derived from one of the existing similar cases within the standard such as for an exposed roThe Australian wind loading standard, AS1170.2 cantilevered roofs in 2002

Melbourne and Cheung coefficients around these types of structures were notably higher than had been previously assumed.In 2004, New Zealand and Australia combined

Strut 1

Strengthening

For the purposes of discussion in later sections, the critical sections of the roof steel structure are . The same terms apply when discussing the


e sports facilities, the first floor contains the public concourse and the top floor contains the members area, known as the Legends Lounge. The lateral resisting structure consists of a braced steel structure, with both eccentrically (Kdirection and steel moment resisting frames in the easton raking steel beams and the suspended floors are generally constructed from hollowcore precast

rete units with an in-situ concrete topping slabs. A typical section of the TSB Stand is provided in

Figure 2 & 3 –

HIGH WIND DAMAGE:

2012, the TSB Stand suffered high wind related damage from a gust event(s) from the south est which loaded the underslung

held the roofing to the underside of the RHS purlins.The damage occurred on the SW tip of the TSB Stand and covered an area of 90 to 120mFigure 3 above for an annotation of the failure area.

uent investigation of the roof claddingfor damage, it was raised to the stadium owner that the understanding of high wind loads relative to large

d changed since the design of the original structure. Therefore the engineering stadium was extended to allow assessment of the primary structure as well

to establish whether the structure was exposed to hiunderstood and to then be able to manage that risk in an informed manner. This wind structural assessment, the findings and associated implementation is the subject of this paper.

ROOF ASSESSMENT:

Standards The structure was designed under NZS4203:1992, which does not specifically cover large cantilevered roofs. However an assumed basis for design was likely derived from one of the existing similar cases within the standard such as for an exposed roThe Australian wind loading standard, AS1170.2

2002, after research into wind behavioMelbourne and Cheung

coefficients around these types of structures were notably higher than had been previously assumed.In 2004, New Zealand and Australia combined



e sports facilities, the first floor contains the public concourse and the top floor contains the members area, known as the Legends Lounge. The lateral resisting structure consists of a braced steel structure, with both eccentrically (K-braces) and concendirection and steel moment resisting frames in the easton raking steel beams and the suspended floors are generally constructed from hollowcore precast

situ concrete topping slabs. A typical section of the TSB Stand is provided in

– TSB Stand Typical Section and

HIGH WIND DAMAGE:

2012, the TSB Stand suffered high wind related damage from a gust event(s) from the south est which loaded the underslung roof such that it caused the roofing to puncture through the fixings that

held the roofing to the underside of the RHS purlins.The damage occurred on the SW tip of the TSB Stand and covered an area of 90 to 120m

n of the failure area.uent investigation of the roof cladding

stadium owner that the understanding of high wind loads relative to large d changed since the design of the original structure. Therefore the engineering


ROOF ASSESSMENT:

The structure was designed under NZS4203:1992, which does not specifically cover large cantilevered roofs. However an assumed basis for design was likely derived from one of the existing similar cases within the standard such as for an exposed roThe Australian wind loading standard, AS1170.2

, after research into wind behavioMelbourne and Cheung in 1985. This

coefficients around these types of structures were notably higher than had been previously assumed.In 2004, New Zealand and Australia combined



e sports facilities, the first floor contains the public concourse and the top floor contains the members area, known as the Legends Lounge. The lateral resisting structure consists of a braced steel

braces) and concendirection and steel moment resisting frames in the easton raking steel beams and the suspended floors are generally constructed from hollowcore precast


TSB Stand Typical Section and

2012, the TSB Stand suffered high wind related damage from a gust event(s) from the south roof such that it caused the roofing to puncture through the fixings that

held the roofing to the underside of the RHS purlins.The damage occurred on the SW tip of the TSB Stand and covered an area of 90 to 120m

n of the failure area.uent investigation of the roof cladding



The structure was designed under NZS4203:1992, which does not specifically cover large cantilevered roofs. However an assumed basis for design was likely derived from one of the existing similar cases within the standard such as for an exposed roof. The Australian wind loading standard, AS1170.2

, after research into wind behavio. This research, amongst others, suggested that the net pressure

coefficients around these types of structures were notably higher than had been previously assumed.In 2004, New Zealand and Australia combined their

Main Column




braces) and concentrically braced (rod bracing), in the northdirection and steel moment resisting frames in the east-west direction. Concrete bleachers are supported on raking steel beams and the suspended floors are generally constructed from hollowcore precast


TSB Stand Typical Section and


held the roofing to the underside of the RHS purlins. The damage occurred on the SW tip of the TSB Stand and covered an area of 90 to 120m

n of the failure area. uent investigation of the roof cladding failure and inspection of the balance of the roof


stadium was extended to allow assessment of the primary structure as wellto establish whether the structure was exposed to higher wind related risk than was previously understood and to then be able to manage that risk in an informed manner. This wind structural assessment, the findings and associated implementation is the subject of this paper.

The structure was designed under NZS4203:1992, which does not specifically cover large cantilevered roofs. However an assumed basis for design was likely derived from one of the existing similar cases

The Australian wind loading standard, AS1170.2 (1989) , after research into wind behavio

research, amongst others, suggested that the net pressure coefficients around these types of structures were notably higher than had been previously assumed.

their loadings standards into AS/NZS1170, Appendix D

Column

For the purposes of discussion in later sections, the critical sections of the roof steel structure are . The same terms apply when discussing the East or West Stand roof structures.



trically braced (rod bracing), in the northwest direction. Concrete bleachers are supported

on raking steel beams and the suspended floors are generally constructed from hollowcore precast situ concrete topping slabs. A typical section of the TSB Stand is provided in

TSB Stand Typical Section and Perspective View


The damage occurred on the SW tip of the TSB Stand and covered an area of 90 to 120m

failure and inspection of the balance of the roof stadium owner that the understanding of high wind loads relative to large


gher wind related risk than was previously understood and to then be able to manage that risk in an informed manner. This wind structural assessment, the findings and associated implementation is the subject of this paper.


initially introduced provisions to cover large , after research into wind behaviour around stadium, stand like large cantilever


loadings standards into AS/NZS1170, Appendix D

For the purposes of discussion in later sections, the critical sections of the roof steel structure are East or West Stand roof structures.





Perspective View







initially introduced provisions to cover large r around stadium, stand like large cantilever








Perspective View




d changed since the design of the original structure. Therefore the engineering stadium was extended to allow assessment of the primary structure as well. The intent











Perspective View


The damage occurred on the SW tip of the TSB Stand and covered an area of 90 to 120m2


d changed since the design of the original structure. Therefore the engineering he intent of this was

gher wind related risk than was previously understood and to then be able to manage that risk in an informed manner. This wind structural





2012 Failure Zone




trically braced (rod bracing), in the north-south west direction. Concrete bleachers are supported



2. Refer to


d changed since the design of the original structure. Therefore the engineering scopeof this was






2012 Failure Zone

For the purposes of discussion in later sections, the critical sections of the roof steel structure are



south west direction. Concrete bleachers are supported



. Refer to


scope of this was




research, amongst others, suggested that the net pressure

loadings standards into AS/NZS1170, Appendix D5

of 1170.2 (wind loadings standard for Australia and New Zealand) formalized the findings from earlier works. In this standard, the suggested net pressure distribution on a large cantilever roof was represented by a triangular profile that tapered to the supositive or negative, but the magnitude of the coefficient changed with the sign and with the relativity of the area concerned relative to the structures edge.In 2011 AS/NZS1170.2 Appendix Dwas to increase the net pressure distribution from a triangular form to that of a trapezoid. This was notified by to assess the roof for wind loading. The current aligned toward the tip of the cantilever is as follows in

The above illustrateand the significance of the uplift case which was critical in this instance. within Ap

• • •

•

•

Assessment of the Roof StructureThe steel structure of the various wind loading cases from all directions. The model extent was such that the vertical frames were extended to the foundation level with a sensitivity analysis applied to the level of rotational restraint in plane of structural capacity in the truss out of plane direction.It was found however that the actions on any structural elements such that they did not meet their current code capacity under NZS3404.Detailed Assessment of the Critical StrutIn the uplift load combination depicted in compression tcolumn at the highest point of the stadium. Therefore buckling sensitivity is the most signiderive capacity.

•

•

of 1170.2 (wind loadings standard for Australia and New Zealand) formalized the findings from earlier works. In this standard, the suggested net pressure distribution on a large cantilever roof was represented by a triangular profile that tapered to the supositive or negative, but the magnitude of the coefficient changed with the sign and with the relativity of the area concerned relative to the structures edge.In 2011 AS/NZS1170.2 Appendix Dwas to increase the net pressure distribution from a triangular form to that of a trapezoid. This was notified by IPENZ in to assess the roof for wind loading. The current aligned toward the tip of the cantilever is as follows in

The above illustrateand the significance of the uplift case which was critical in this instance. within Appendix D

Downward loads from wind are also significant. Roof loading varies relative to the offset from the sides of the stand. These significant load cases only occur when the wind direction is within a 90 degree plan ar

the wind direction other typical structures.the NW, W and SW

The method in limitations and allowances respectively and non

AS/NZSshapes)and roof fixings). Therefore testing and judgment of the engineer is required in these instances.

Assessment of the Roof StructureThe steel structure of the various wind loading cases from all directions. The model extent was such that the vertical frames were extended to the foundation level with a sensitivity analysis applied to the level of rotational restraint in plane of the truss/frame portal. Out of plane the main trusses of the stadium structural capacity in the truss out of plane direction.It was found however that the

ns on any structural elements such that they did not meet their current code capacity under NZS3404. Detailed Assessment of the Critical StrutIn the uplift load combination depicted in compression this element is 15m long approximately (L) from the bottom chord intersection to the main column at the highest point of the stadium. Therefore buckling sensitivity is the most signiderive capacity.

The potential fthese mechanisms were either weak or governed by poor connections (purlin to chord).

The out of plane restraint and stiffness of the main column where it cantilevered out of above the purlin

of 1170.2 (wind loadings standard for Australia and New Zealand) formalized the findings from earlier works. In this standard, the suggested net pressure distribution on a large cantilever roof was represented by a triangular profile that tapered to the supositive or negative, but the magnitude of the coefficient changed with the sign and with the relativity of the area concerned relative to the structures edge.In 2011 AS/NZS1170.2 Appendix Dwas to increase the net pressure distribution from a triangular form to that of a trapezoid. This was

IPENZ in 2011to assess the roof for wind loading. The current aligned toward the tip of the cantilever is as follows in

Figure 5 The above illustrates the increasing magnitude of the Cpn for these and the significance of the uplift case which was critical in this instance.

pendix D5 relevant to these types of roofs:Downward loads from wind are also significant.Roof loading varies relative to the offset from the sides of the stand.These significant load cases only occur when the wind direction is within a 90 degree plan arthe wind direction other typical structures.the NW, W and SWThe method in AS/NZSlimitations and allowances respectively and nonAS/NZS1170.2 Appendix D does not reference localized pressure factors

apes) for vortices or other mechanisms that are often critical for and roof fixings). Therefore testing and judgment of the engineer is required in these instances.

Assessment of the Roof StructureThe steel structure of the various wind loading cases from all directions. The model extent was such that the vertical frames were extended to the foundation level with a sensitivity analysis applied to the level of rotational restraint in

russ/frame portal. Out of plane the main trusses of the stadium structural capacity in the truss out of plane direction.It was found however that the

ns on any structural elements such that they did not meet their current code capacity under

Detailed Assessment of the Critical StrutIn the uplift load combination depicted in

his element is 15m long approximately (L) from the bottom chord intersection to the main column at the highest point of the stadium. Therefore buckling sensitivity is the most signiderive capacity. In doing so we considered:

The potential for rotational restraint at the bottom chord and the midspan vertical strutthese mechanisms were either weak or governed by poor connections (purlin to chord).The out of plane restraint and stiffness of the main column where it cantilevered out of above the purlin

of 1170.2 (wind loadings standard for Australia and New Zealand) formalized the findings from earlier works. In this standard, the suggested net pressure distribution on a large cantilever roof was represented by a triangular profile that tapered to the supositive or negative, but the magnitude of the coefficient changed with the sign and with the relativity of the area concerned relative to the structures edge.In 2011 AS/NZS1170.2 Appendix Dwas to increase the net pressure distribution from a triangular form to that of a trapezoid. This was

2011 as part of the draft update of to assess the roof for wind loading. The current aligned toward the tip of the cantilever is as follows in

Figure 5 – Cantilever Roof Wind the increasing magnitude of the Cpn for these

and the significance of the uplift case which was critical in this instance. relevant to these types of roofs:

Downward loads from wind are also significant.Roof loading varies relative to the offset from the sides of the stand.These significant load cases only occur when the wind direction is within a 90 degree plan arthe wind direction indicated in Figure 5other typical structures. Therefore the TSB Stand roof is exposed to the NW, W and SW directions

AS/NZS1170.2 limitations and allowances respectively and non

1170.2 Appendix D does not reference localized pressure factorsfor vortices or other mechanisms that are often critical for

and roof fixings). Therefore testing and judgment of the engineer is required in these instances.Assessment of the Roof StructureThe steel structure of the roof was computer various wind loading cases from all directions. The model extent was such that the vertical frames were extended to the foundation level with a sensitivity analysis applied to the level of rotational restraint in

russ/frame portal. Out of plane the main trusses of the stadium structural capacity in the truss out of plane direction.It was found however that the AS/NZS

ns on any structural elements such that they did not meet their current code capacity under

Detailed Assessment of the Critical StrutIn the uplift load combination depicted in

his element is 15m long approximately (L) from the bottom chord intersection to the main column at the highest point of the stadium. Therefore buckling sensitivity is the most signi

n doing so we considered:or rotational restraint at the bottom chord and the midspan vertical strut

these mechanisms were either weak or governed by poor connections (purlin to chord).The out of plane restraint and stiffness of the main column where it cantilevered out of above the purlin plane to restrain Strut 1.

1.5

of 1170.2 (wind loadings standard for Australia and New Zealand) formalized the findings from earlier works. In this standard, the suggested net pressure distribution on a large cantilever roof was represented by a triangular profile that tapered to the supositive or negative, but the magnitude of the coefficient changed with the sign and with the relativity of the area concerned relative to the structures edge.In 2011 AS/NZS1170.2 Appendix D5 was revised, due to further work in this area. The significant change was to increase the net pressure distribution from a triangular form to that of a trapezoid. This was

as part of the draft update of to assess the roof for wind loading. The current aligned toward the tip of the cantilever is as follows in

Cantilever Roof Wind the increasing magnitude of the Cpn for these


Downward loads from wind are also significant.Roof loading varies relative to the offset from the sides of the stand.These significant load cases only occur when the wind direction is within a 90 degree plan ar

indicated in Figure 5Therefore the TSB Stand roof is exposed to

directions. 1170.2 Appendix D also includes dimensional

limitations and allowances respectively and non1170.2 Appendix D does not reference localized pressure factorsfor vortices or other mechanisms that are often critical for

and roof fixings). Therefore testing and judgment of the engineer is required in these instances.Assessment of the Roof Structure

roof was computer various wind loading cases from all directions. The model extent was such that the vertical frames were extended to the foundation level with a sensitivity analysis applied to the level of rotational restraint in

russ/frame portal. Out of plane the main trusses of the stadium structural capacity in the truss out of plane direction.

AS/NZS1170.2 Appendix D conditions were the only case that caused ns on any structural elements such that they did not meet their current code capacity under

Detailed Assessment of the Critical StrutIn the uplift load combination depicted in F


n doing so we considered:or rotational restraint at the bottom chord and the midspan vertical strut

these mechanisms were either weak or governed by poor connections (purlin to chord).The out of plane restraint and stiffness of the main column where it cantilevered out of

to restrain Strut 1.

of 1170.2 (wind loadings standard for Australia and New Zealand) formalized the findings from earlier works. In this standard, the suggested net pressure distribution on a large cantilever roof was represented by a triangular profile that tapered to the support region of the cantilever. The pressure could be either positive or negative, but the magnitude of the coefficient changed with the sign and with the relativity of the area concerned relative to the structures edge.

s revised, due to further work in this area. The significant change was to increase the net pressure distribution from a triangular form to that of a trapezoid. This was

as part of the draft update of to assess the roof for wind loading. The current (and previous) aligned toward the tip of the cantilever is as follows in

Cantilever Roof Wind the increasing magnitude of the Cpn for these


Downward loads from wind are also significant.Roof loading varies relative to the offset from the sides of the stand.These significant load cases only occur when the wind direction is within a 90 degree plan ar

indicated in Figure 5 aboveTherefore the TSB Stand roof is exposed to

Appendix D also includes dimensionallimitations and allowances respectively and non


and roof fixings). Therefore testing and judgment of the engineer is required in these instances.

roof was computer modelledvarious wind loading cases from all directions. The model extent was such that the vertical frames were extended to the foundation level with a sensitivity analysis applied to the level of rotational restraint in


1170.2 Appendix D conditions were the only case that caused ns on any structural elements such that they did not meet their current code capacity under

Detailed Assessment of the Critical Strut Figure 5, Strut 1 assumes a compression load. When under


n doing so we considered: or rotational restraint at the bottom chord and the midspan vertical strut

these mechanisms were either weak or governed by poor connections (purlin to chord).The out of plane restraint and stiffness of the main column where it cantilevered out of

to restrain Strut 1.

0.0

of 1170.2 (wind loadings standard for Australia and New Zealand) formalized the findings from earlier works. In this standard, the suggested net pressure distribution on a large cantilever roof was represented

pport region of the cantilever. The pressure could be either positive or negative, but the magnitude of the coefficient changed with the sign and with the relativity of

s revised, due to further work in this area. The significant change

was to increase the net pressure distribution from a triangular form to that of a trapezoid. This was as part of the draft update of AS/NZS

(and previous) aligned toward the tip of the cantilever is as follows in Figure 5

Cantilever Roof Wind Pressure Coefficients in 1170.2the increasing magnitude of the Cpn for these


Downward loads from wind are also significant. Roof loading varies relative to the offset from the sides of the stand.These significant load cases only occur when the wind direction is within a 90 degree plan ar

above, in other cases the windTherefore the TSB Stand roof is exposed to

Appendix D also includes dimensionallimitations and allowances respectively and non-conformance can still require wind tunnel testing.



modelled in spacegassvarious wind loading cases from all directions. The model extent was such that the vertical frames were extended to the foundation level with a sensitivity analysis applied to the level of rotational restraint in



igure 5, Strut 1 assumes a compression load. When under his element is 15m long approximately (L) from the bottom chord intersection to the main

column at the highest point of the stadium. Therefore buckling sensitivity is the most signi

or rotational restraint at the bottom chord and the midspan vertical strutthese mechanisms were either weak or governed by poor connections (purlin to chord).The out of plane restraint and stiffness of the main column where it cantilevered out of

0.0




AS/NZS1170.2(and previous) pressure distribution coefficients for wind

Figure 5:

Pressure Coefficients in 1170.2the increasing magnitude of the Cpn for these types of

and the significance of the uplift case which was critical in this instance.

Roof loading varies relative to the offset from the sides of the stand.These significant load cases only occur when the wind direction is within a 90 degree plan ar

in other cases the windTherefore the TSB Stand roof is exposed to

Appendix D also includes dimensionalconformance can still require wind tunnel testing.



in spacegass as a 3D frame and assessed under various wind loading cases from all directions. The model extent was such that the vertical frames were extended to the foundation level with a sensitivity analysis applied to the level of rotational restraint in

russ/frame portal. Out of plane the main trusses of the stadium





1.8




1170.2, and was the baspressure distribution coefficients for wind

Pressure Coefficients in 1170.2types of roofs that occurred

and the significance of the uplift case which was critical in this instance. The following was a

Roof loading varies relative to the offset from the sides of the stand. These significant load cases only occur when the wind direction is within a 90 degree plan ar

in other cases the windTherefore the TSB Stand roof is exposed to governing

Appendix D also includes dimensional conformance can still require wind tunnel testing.

1170.2 Appendix D does not reference localized pressure factorsfor vortices or other mechanisms that are often critical for secondary


as a 3D frame and assessed under various wind loading cases from all directions. The model extent was such that the vertical frames were extended to the foundation level with a sensitivity analysis applied to the level of rotational restraint in

russ/frame portal. Out of plane the main trusses of the stadium were





1.8




, and was the baspressure distribution coefficients for wind

Pressure Coefficients in 1170.2roofs that occurred

The following was a

These significant load cases only occur when the wind direction is within a 90 degree plan arin other cases the wind load on the roof is

governing

and dynamic amplification conformance can still require wind tunnel testing.

1170.2 Appendix D does not reference localized pressure factors (as per other roofing secondary elements (ie purlins



were half modelled








, and was the basis for the advice pressure distribution coefficients for wind

Pressure Coefficients in 1170.2 roofs that occurred

The following was also notable

These significant load cases only occur when the wind direction is within a 90 degree plan arload on the roof is

wind loads from


(as per other roofing elements (ie purlins



modelled



column at the highest point of the stadium. Therefore buckling sensitivity is the most significant issue to

or rotational restraint at the bottom chord and the midspan vertical strut. Hthese mechanisms were either weak or governed by poor connections (purlin to chord). The out of plane restraint and stiffness of the main column where it cantilevered out of plane

1.




is for the advice pressure distribution coefficients for wind

roofs that occurred over time lso notable

These significant load cases only occur when the wind direction is within a 90 degree plan arc of load on the roof is as per

wind loads from


(as per other roofing elements (ie purlins



to assess



ficant issue to

However

plane

1.1




is for the advice pressure distribution coefficients for wind

time lso notable

c of

conformance can still require wind tunnel testing.

elements (ie purlins

to assess

•

Given the above issues, the effective length of strut 1 relative to compression buckling was where Ke was in the range of 0.85 to 1.0offer sin the analysis, but given the bending stability of the section and the small moments involved, compression buckling governed.The results of the assessment

Ke

1.00 0.85 0.50 Comments on the above table are as follows:

• • •

•

LegislationAs referenced abovestrengthening would be required of the structure under the Building Actwind loading.Howeverthe following

• • • •

5.

From review of Table 1 above, it is clear that stabilizing Strut 1 laterally at its midspanrequired to allow the existing structure to operate as close as practical to a new structure.To stabilize the strut

• •

The first option of the two was selected for the following rational:1.2.

3.

See an

The ability of the main column to also offer torsional restraint (in plan) to Strut 1, thereby offering an out of

Given the above issues, the effective length of strut 1 relative to compression buckling was where Ke was in the range of 0.85 to 1.0offer some rotational restraint in the analysis, but given the bending stability of the section and the small moments involved, compression buckling governed.The results of the assessment

Phi.Ncy(kNm)

327 455 1,097

Comments on the above table are as follows: V,des derived from an IL3 wind event (1000 year AEP), and an Mz,cat = V,actual The AEP derives from a reverse calculation of

to determine the event risk that would not cause failure.below to depict this

Therefore the strut had 10 to standards. (seismic loading

Legislation As referenced abovestrengthening would be required of the structure under the Building Actwind loading. However, both TRC and the following:

The level of increased relative risk; The number of parties that may attend a large event The nearby residen The unknown extent of area affected by a structural failure of such a large roof.

5. STRENGTHENING SCHEMEFrom review of Table 1 above, it is clear that stabilizing Strut 1 laterally at its midspanrequired to allow the existing structure to operate as close as practical to a new structure.To stabilize the strut

A transverse A localized fly brace system to brace the vertical strut below Strut 1 at midspa

purlins to either side of the truss.The first option of the two was selected for the following rational:

1. A strut and brace system did not clash with another reroof project to be atop the existing RHS’s.2. The fly brace system utilized existing

highly loaded.3. The fly brace option would have required hot work very close to the existing roofing which was

already known to have leakage and durability issues (reference the roofing failure).See an elevated half section of the transverse strut and brace system adopted below

The ability of the main column to also offer torsional restraint (in plan) to Strut 1, thereby offering an out of plane

Given the above issues, the effective length of strut 1 relative to compression buckling was where Ke was in the range of 0.85 to 1.0

ome rotational restraint in the analysis, but given the bending stability of the section and the small moments involved, compression buckling governed.The results of the assessment

Phi.Ncy (kNm)

Phi.Mcy(kNm)

139 139

1,097 139Comments on the above table are as follows:

des derived from an IL3 wind event (1000 year AEP), and an Mz,cat = actual derives from a gust speed that generates a unity check in the capacity calculation.

The AEP derives from a reverse calculation of to determine the event risk that would not cause failure.below to depict this

Therefore the strut had 10 to standards. (This could be considered as equivalent to an easeismic loading).

As referenced above, if the actions were derived from seismic strengthening would be required of the structure under the Building Act

both TRC and

he level of increased relative risk;he number of parties that may attend a large eventhe nearby residen

The unknown extent of area affected by a structural failure of such a large roof.

STRENGTHENING SCHEMEFrom review of Table 1 above, it is clear that stabilizing Strut 1 laterally at its midspanrequired to allow the existing structure to operate as close as practical to a new structure.To stabilize the strut:

A transverse strut and brace system, and;A localized fly brace system to brace the vertical strut below Strut 1 at midspapurlins to either side of the truss.

The first option of the two was selected for the following rational:A strut and brace system did not clash with another reroof project to be atop the existing RHS’s.The fly brace system utilized existing highly loaded. The fly brace option would have required hot work very close to the existing roofing which was already known to have leakage and durability issues (reference the roofing failure).elevated half section of the transverse strut and brace system adopted below

The ability of the main column to also offer torsional restraint (in plan) to Strut 1, thereby offering moment end connection to strut 1.

Given the above issues, the effective length of strut 1 relative to compression buckling was where Ke was in the range of 0.85 to 1.0

ome rotational restraint available by the strut end conditionsin the analysis, but given the bending stability of the section and the small moments involved, compression buckling governed. The results of the assessment were as follows

Table 1: Phi.Mcy (kNm)

139 139 139

Comments on the above table are as follows:des derived from an IL3 wind event (1000 year AEP), and an Mz,cat =

derives from a gust speed that generates a unity check in the capacity calculation.The AEP derives from a reverse calculation of to determine the event risk that would not cause failure.below to depict this (note this is for V,r rather than V,des)

Therefore the strut had 10 to This could be considered as equivalent to an ea

).

if the actions were derived from seismic strengthening would be required of the structure under the Building Act

both TRC and NPDC deemed it appropriate to investigate strengthening of the stands

he level of increased relative risk;he number of parties that may attend a large eventhe nearby residential housing;


STRENGTHENING SCHEMEFrom review of Table 1 above, it is clear that stabilizing Strut 1 laterally at its midspanrequired to allow the existing structure to operate as close as practical to a new structure.

trut and brace system, and;A localized fly brace system to brace the vertical strut below Strut 1 at midspapurlins to either side of the truss.

The first option of the two was selected for the following rational:A strut and brace system did not clash with another reroof project to be atop the existing RHS’s.The fly brace system utilized existing

The fly brace option would have required hot work very close to the existing roofing which was already known to have leakage and durability issues (reference the roofing failure).elevated half section of the transverse strut and brace system adopted below


Given the above issues, the effective length of strut 1 relative to compression buckling was where Ke was in the range of 0.85 to 1.0. This was

available by the strut end conditionsin the analysis, but given the bending stability of the section and the small moments involved,

were as follows

Table 1: Strut 1 N*/Phi.Ncy + M*/Phi.Mcy <=

1.0 (vs 100% of 1170.2)

Comments on the above table are as follows:des derived from an IL3 wind event (1000 year AEP), and an Mz,cat =

derives from a gust speed that generates a unity check in the capacity calculation.The AEP derives from a reverse calculation of to determine the event risk that would not cause failure.

(note this is for V,r rather than V,des)

Therefore the strut had 10 to 20 times the relative risk of a new structure designed to current

This could be considered as equivalent to an ea


NPDC deemed it appropriate to investigate strengthening of the stands

he level of increased relative risk;he number of parties that may attend a large event

tial housing; The unknown extent of area affected by a structural failure of such a large roof.

STRENGTHENING SCHEMEFrom review of Table 1 above, it is clear that stabilizing Strut 1 laterally at its midspanrequired to allow the existing structure to operate as close as practical to a new structure.

trut and brace system, and;A localized fly brace system to brace the vertical strut below Strut 1 at midspapurlins to either side of the truss.

The first option of the two was selected for the following rational:A strut and brace system did not clash with another reroof project to be atop the existing RHS’s.The fly brace system utilized existing



Given the above issues, the effective length of strut 1 relative to compression buckling was . This was


were as follows in Table 1trut 1 – Wind Assessment Results

N*/Phi.Ncy + M*/Phi.Mcy <= (vs 100% of 1170.2)

1.81 1.30 0.63

Comments on the above table are as follows: des derived from an IL3 wind event (1000 year AEP), and an Mz,cat =

derives from a gust speed that generates a unity check in the capacity calculation.The AEP derives from a reverse calculation of to determine the event risk that would not cause failure.


0 times the relative risk of a new structure designed to current This could be considered as equivalent to an ea



he level of increased relative risk; he number of parties that may attend a large event


STRENGTHENING SCHEME From review of Table 1 above, it is clear that stabilizing Strut 1 laterally at its midspanrequired to allow the existing structure to operate as close as practical to a new structure.

trut and brace system, and; A localized fly brace system to brace the vertical strut below Strut 1 at midspa

The first option of the two was selected for the following rational:

A strut and brace system did not clash with another reroof project to be atop the existing RHS’s.The fly brace system utilized existing elements and connections that were either weak and/or



Given the above issues, the effective length of strut 1 relative to compression buckling was . This was to reflect the potential of the boundary conditions to


in Table 1, under the load combination of 0.9G & Wuplift:Wind Assessment Results

N*/Phi.Ncy + M*/Phi.Mcy <= (vs 100% of 1170.2)

des derived from an IL3 wind event (1000 year AEP), and an Mz,cat = derives from a gust speed that generates a unity check in the capacity calculation.

The AEP derives from a reverse calculation of the equation, to determine the event risk that would not cause failure.


0 times the relative risk of a new structure designed to current This could be considered as equivalent to an ea



he number of parties that may attend a large event


From review of Table 1 above, it is clear that stabilizing Strut 1 laterally at its midspanrequired to allow the existing structure to operate as close as practical to a new structure.

A localized fly brace system to brace the vertical strut below Strut 1 at midspa

The first option of the two was selected for the following rational:A strut and brace system did not clash with another reroof project to be atop the existing RHS’s.

elements and connections that were either weak and/or


The ability of the main column to also offer torsional restraint (in plan) to Strut 1, thereby offering

Given the above issues, the effective length of strut 1 relative to compression buckling was to reflect the potential of the boundary conditions to

available by the strut end conditions. Induced moments were also included in the analysis, but given the bending stability of the section and the small moments involved,

, under the load combination of 0.9G & Wuplift:Wind Assessment Results

N*/Phi.Ncy + M*/Phi.Mcy <=

V,des(m/s)

41.041.041.0


equation, AS/NZSto determine the event risk that would not cause failure. See a part extract from

(note this is for V,r rather than V,des).

0 times the relative risk of a new structure designed to current This could be considered as equivalent to an earthquake prone building under

if the actions were derived from seismic loading strengthening would be required of the structure under the Building Act


he number of parties that may attend a large event;




The first option of the two was selected for the following rational: A strut and brace system did not clash with another reroof project to be atop the existing RHS’s.

elements and connections that were either weak and/or




. Induced moments were also included in the analysis, but given the bending stability of the section and the small moments involved,

, under the load combination of 0.9G & Wuplift:Wind Assessment Results

des (m/s)

Strut 1 V,

41.0 41.0 41.0


AS/NZS1170.2, table 3.1 region A7See a part extract from

0 times the relative risk of a new structure designed to current rthquake prone building under

loading and the level of risk was such strengthening would be required of the structure under the Building Act. But, no such legislation exists for





A strut and brace system did not clash with another reroof project to be atop the existing RHS’s.elements and connections that were either weak and/or





, under the load combination of 0.9G & Wuplift: Strut 1 -,allowable

(m/s) 32.0 36.0 56.0

des derived from an IL3 wind event (1000 year AEP), and an Mz,cat = (15m,C3derives from a gust speed that generates a unity check in the capacity calculation.

1170.2, table 3.1 region A7See a part extract from


and the level of risk was such no such legislation exists for



From review of Table 1 above, it is clear that stabilizing Strut 1 laterally at its midspan is all that is required to allow the existing structure to operate as close as practical to a new structure.

A localized fly brace system to brace the vertical strut below Strut 1 at midspan to the RHS


The fly brace option would have required hot work very close to the existing roofing which was already known to have leakage and durability issues (reference the roofing failure).elevated half section of the transverse strut and brace system adopted below in Figure 6.


Given the above issues, the effective length of strut 1 relative to compression buckling was Ke X L = Leto reflect the potential of the boundary conditions to


, under the load combination of 0.9G & Wuplift:

llowable

1776

>>5,0

(15m,C3) = 0.89derives from a gust speed that generates a unity check in the capacity calculation.

1170.2, table 3.1 region A7See a part extract from AS/NZS


and the level of risk was such no such legislation exists for



is all that is required to allow the existing structure to operate as close as practical to a new structure.

n to the RHS


The fly brace option would have required hot work very close to the existing roofing which was already known to have leakage and durability issues (reference the roofing failure).

in Figure 6.


Ke X L = Le, to reflect the potential of the boundary conditions to

. Induced moments were also included

, under the load combination of 0.9G & Wuplift:

AEP

17 years 76 years 5,000 years

89. derives from a gust speed that generates a unity check in the capacity calculation.

1170.2, table 3.1 region A7 AS/NZS1170


and the level of risk was such that no such legislation exists for

NPDC deemed it appropriate to investigate strengthening of the stands due to

is all that is

n to the RHS

A strut and brace system did not clash with another reroof project to be atop the existing RHS’s. elements and connections that were either weak and/or

The fly brace option would have required hot work very close to the existing roofing which was

in Figure 6.


,

. Induced moments were also included

00 years

no such legislation exists for

4. CONCEPT DISCUSSIONDue to the location of works, a number of issues became more important to considergenerally as follows:Construction SafetyThe works were required to be fitted onthe stadium roof, 14m in the air roofing that had historically been subject to damage by servicemenwas already the subject of a water tightness review of existing leakage. There was an area of age/UV embrittled opaque roofing that separated the area ofixed roofing over the members lounge areasThis area of roofing had a without mesh. It had also been installed in such a manner that repair/replacement of this roof would be expensive.Construction AcDue to the roof height and accessibility of the works areas, access was required to be considered early to assist in mitigating construction safety, maintaining quality and planning for a reasonable construction form.more awkward the access, the longer contractors would be exposed to the risks of working on the roof.Construction QualityThis was a concern for both existing stand features and for any new elementsconstruction activity damaging the exiwas high, while any new works up on the roof would be of lesser quality due to the extreme access issues.Safety in DesignDue to the preceding issues and and NPDC appreciating them, we were able to bring in the contractor early to derive the benefits of the client, operators and the contractor FEGL) process issues above. This allowed a collaborative approach throughout the project l 5. DETAILED DESIGN:

From early conception the intent of the design was to • Transverse c

CONCEPT DISCUSSIONDue to the location of works, a number of issues became more important to considergenerally as follows:Construction SafetyThe works were required to be fitted onthe stadium roof, 14m in the air roofing that had historically been subject to damage by servicemenwas already the subject of a water tightness review of existing leakage. There was an area of age/UV embrittled opaque roofing that separated the area of works from the more accessiblefixed roofing over the members lounge areas

his area of roofing had a without mesh. It had also been installed in such a manner that repair/replacement of this roof would be expensive.Construction AcDue to the roof height and accessibility of the works areas, access was required to be considered early to assist in mitigating construction safety, maintaining quality and planning for a reasonable construction form.more awkward the access, the longer contractors would be exposed to the risks of working on the roof.Construction QualityThis was a concern for both existing stand features and for any new elementsconstruction activity damaging the exiwas high, while any new works up on the roof would be of lesser quality due to the extreme access issues. Safety in DesignDue to the preceding issues and

NPDC appreciating them, we were able to bring in the contractor early to derive the

nefits of the client, operators and the contractor (Fitzroy Engineering Group Limited FEGL) being on board with a safety in design process as well as issues above. This allowed a collaborative approach throughout the project l

DETAILED DESIGN:From early conception the intent of the design was to have the following features:

Transverse c

Figure 6

CONCEPT DISCUSSIONDue to the location of works, a number of issues became more important to considergenerally as follows: Construction Safety The works were required to be fitted onthe stadium roof, 14m in the air roofing that had historically been subject to damage by servicemen.was already the subject of a water tightness review of existing leakage. There was an area of age/UV embrittled opaque roofing that separated

works from the more accessiblefixed roofing over the members lounge areas

his area of roofing had a without mesh. It had also been installed in such a manner that repair/replacement of this roof would be expensive. Construction Access Due to the roof height and accessibility of the works areas, access was required to be considered early to assist in mitigating construction safety, maintaining quality and planning for a reasonable construction form.more awkward the access, the longer contractors would be exposed to the risks of working on the roof. Construction Quality This was a concern for both existing stand features and for any new elementsconstruction activity damaging the exiwas high, while any new works up on the roof would be of lesser quality due to the extreme

Safety in Design Due to the preceding issues and

NPDC appreciating them, we were able to bring in the contractor early to derive the

nefits of the client, operators and the (Fitzroy Engineering Group Limited

being on board with a safety in design as well as specifically address

issues above. This allowed a collaborative approach throughout the project l

DETAILED DESIGN:From early conception the intent of the design

have the following features:Transverse collector

Figure 6 –Transverse Strut and Brace Strengthening Concept

CONCEPT DISCUSSIONDue to the location of works, a number of issues became more important to consider

The works were required to be fitted onthe stadium roof, 14m in the air and across roofing that had historically been subject to

. The underswas already the subject of a water tightness review of existing leakage. There was an area of age/UV embrittled opaque roofing that separated


his area of roofing had a 5m fall beneath it without mesh. It had also been installed in such a manner that repair/replacement of this roof

Due to the roof height and accessibility of the works areas, access was required to be considered early to assist in mitigating construction safety, maintaining quality and planning for a reasonable construction form.more awkward the access, the longer contractors would be exposed to the risks of

This was a concern for both existing stand features and for any new elementsconstruction activity damaging the exiwas high, while any new works up on the roof would be of lesser quality due to the extreme

Due to the preceding issues and NPDC appreciating them, we were able to

bring in the contractor early to derive the nefits of the client, operators and the

(Fitzroy Engineering Group Limited being on board with a safety in design

specifically addressissues above. This allowed a collaborative approach throughout the project l

DETAILED DESIGN: From early conception the intent of the design

have the following features:ollector horizontal

Transverse Strut and Brace Strengthening Concept

CONCEPT DISCUSSION Due to the location of works, a number of issues became more important to consider. These were

The works were required to be fitted on top of and across

roofing that had historically been subject to he underslung roofing

was already the subject of a water tightness review of existing leakage. There was an area of age/UV embrittled opaque roofing that separated


5m fall beneath it without mesh. It had also been installed in such a manner that repair/replacement of this roof

Due to the roof height and accessibility of the works areas, access was required to be considered early to assist in mitigating construction safety, maintaining quality and planning for a reasonable construction form.more awkward the access, the longer contractors would be exposed to the risks of

This was a concern for both existing stand features and for any new elements. The risk of construction activity damaging the existing roof was high, while any new works up on the roof would be of lesser quality due to the extreme

Due to the preceding issues and both the NPDC appreciating them, we were able to

bring in the contractor early to derive the nefits of the client, operators and the

(Fitzroy Engineering Group Limited being on board with a safety in design

specifically addressingissues above. This allowed a collaborative approach throughout the project life.

From early conception the intent of the design have the following features:

horizontal struts that


Due to the location of works, a number of issues hese were

top of and across

roofing that had historically been subject to ung roofing

was already the subject of a water tightness review of existing leakage. There was an area of age/UV embrittled opaque roofing that separated

works from the more accessible top fixed roofing over the members lounge areas.

5m fall beneath it without mesh. It had also been installed in such a manner that repair/replacement of this roof

Due to the roof height and accessibility of the

construction safety, maintaining quality and planning for a reasonable construction form. The

contractors would be exposed to the risks of

This was a concern for both existing stand he risk of sting roof

was high, while any new works up on the roof would be of lesser quality due to the extreme

TRC NPDC appreciating them, we were able to

(Fitzroy Engineering Group Limited - being on board with a safety in design

ing the issues above. This allowed a collaborative

From early conception the intent of the design

struts that


•

•

The for various rational• •

•

The Strut/Brace DesignThe CHS strut design was approach methodology was job specificthe issues noted in strut/brace connection design was generally as follows:•

•

•

•

•


pick up stabilizing loads (assuming they are all additive2.5% of the primary axial load NZS3404

The collector struts are to then be diagonally bottom chord

The existing vertical strut within the truss then transfers texisting roof plane struts and braces, thereby distributing actions into structural system that has redundancy this type of load combination.

The structural braces were selected as CHS’s for various rational Ease of coating. The ability to accommodate significant

compression loads as well as tension. A CHS could be consistently and efficiently

used for all member types while remaining consistent with the exi

The Strut/Brace DesignThe CHS strut design was approach (127CHS)methodology was job specificthe issues noted in strut/brace connection design was generally as follows:

The connection cleat was a kniwelded into the CHS.

Connection of the cleat to the connection on the primary structure was via friction grip(TF) bolting and slotted holes.

The slotted holes allowed for additional site tolerance beyond a site measure, while the TF bolting allowed for a nonload path connection to accommodate the connection play deriving from the slotted holes and the use of bolts in shear to take the axial strut/brace loads.

To mobilizeaction loads, the a specific steel to steel interfaces were coated in an inorganic zinc coating to both provide some corrosion protection while still providing a high friction surface interface to maximize the connection capacity.

In the event of actions exceeding the

BracesTransverse Strut and Brace Strengthening Concept

pick up stabilizing loads (assuming they are all additive, and of the incremental order of 2.5% of the primary axial load NZS3404 1997).The collector struts are to then be diagonally braced to nominally above the bottom chord of the trussThe existing vertical strut within the truss then transfers the stabilizing existing roof plane struts and braces, thereby distributing actions into structural system that has redundancy this type of load combination.

tructural braces were selected as CHS’s for various rational, s

Ease of coating.The ability to accommodate significant compression loads as well as tension.A CHS could be consistently and efficiently used for all member types while remaining consistent with the exi

The Strut/Brace DesignThe CHS strut design was

(127CHS), however the connection methodology was job specificthe issues noted in Sstrut/brace connection design was generally as

The connection cleat was a kniwelded into the CHS.Connection of the cleat to the connection on the primary structure was via friction grip

bolting and slotted holes.The slotted holes allowed for additional site tolerance beyond a site measure, while the

lting allowed for a nonload path connection to accommodate the connection play deriving from the slotted holes and the use of bolts in shear to take the axial strut/brace loads.

mobilize the accumulated stabilizing action loads, the a specific localizedsteel to steel interfaces were coated in an inorganic zinc coating to both provide some corrosion protection while still providing a high friction surface interface to maximize

onnection capacity.In the event of actions exceeding the

Braces Transverse Strut and Brace Strengthening Concept

pick up stabilizing loads (assuming they are and of the incremental order of

2.5% of the primary axial load ).

The collector struts are to then be braced to nominally above the

of the trussThe existing vertical strut within the truss

he stabilizing existing roof plane struts and braces, thereby distributing actions into structural system that has redundancy this type of load combination.

tructural braces were selected as CHS’s , such as:

Ease of coating. The ability to accommodate significant compression loads as well as tension.A CHS could be consistently and efficiently used for all member types while remaining consistent with the existing structure

The Strut/Brace Design The CHS strut design was a conventional

, however the connection methodology was job specific,

Section 4 in mind. The strut/brace connection design was generally as

The connection cleat was a kniwelded into the CHS. Connection of the cleat to the connection on the primary structure was via friction grip

bolting and slotted holes.The slotted holes allowed for additional site tolerance beyond a site measure, while the

lting allowed for a nonload path connection to accommodate the connection play deriving from the slotted holes and the use of bolts in shear to take the axial strut/brace loads.

the accumulated stabilizing action loads, the TF bolt interfaces utilized

localized coating systemsteel to steel interfaces were coated in an inorganic zinc coating to both provide some corrosion protection while still providing a high friction surface interface to maximize

onnection capacity. In the event of actions exceeding the


2.5% of the primary axial load – reference


of the truss. The existing vertical strut within the truss

he stabilizing actionsexisting roof plane struts and braces, thereby distributing actions into an existing structural system that has redundancy this type of load combination.

tructural braces were selected as CHS’s

The ability to accommodate significant compression loads as well as tension.A CHS could be consistently and efficiently used for all member types while remaining

ting structure

conventional , however the connection

, developed with ection 4 in mind. The

strut/brace connection design was generally as

The connection cleat was a knife plate shop

Connection of the cleat to the connection on the primary structure was via friction grip

bolting and slotted holes. The slotted holes allowed for additional site tolerance beyond a site measure, while the

lting allowed for a non-slip primary load path connection to accommodate the connection play deriving from the slotted holes and the use of bolts in shear to take the axial strut/brace loads.

the accumulated stabilizing bolt interfaces utilized

coating systemsteel to steel interfaces were coated in an inorganic zinc coating to both provide some corrosion protection while still providing a high friction surface interface to maximize


Collector Struts


reference


The existing vertical strut within the truss actions to the

existing roof plane struts and braces, an existing

structural system that has redundancy for

tructural braces were selected as CHS’s

The ability to accommodate significant compression loads as well as tension. A CHS could be consistently and efficiently used for all member types while remaining

ting structure.

conventional , however the connection

developed with ection 4 in mind. The


fe plate shop

Connection of the cleat to the connection on the primary structure was via friction grip

The slotted holes allowed for additional site tolerance beyond a site measure, while the

slip primary load path connection to accommodate the connection play deriving from the slotted holes and the use of bolts in shear to take

the accumulated stabilizing bolt interfaces utilized

coating system. The steel to steel interfaces were coated in an inorganic zinc coating to both provide some corrosion protection while still providing a high friction surface interface to maximize


Collector Struts


to the

an existing

A CHS could be consistently and efficiently used for all member types while remaining


fe plate shop

on the primary structure was via friction grip

The slotted holes allowed for additional site tolerance beyond a site measure, while the

bolt interfaces utilized

inorganic zinc coating to both provide some

connectthe member), the joint would slip (whilemaintaining the joint TF new position 10mm offset whereby the bolting can then behave alsoas well. Therefore the connection can be said to have considerable redundancy in it.The 10mm deformation in the strut connections would also have associated deformations in the restrained Hmomthe length of accommodated.

• Refer to Figure strut/brace members, and refer to Figure for the connection details of the strut/braces.

The Strut/Brace DesignThe Sdetailed design is the element that allowed the works to progressfor the following considerations• It

to the primary structure.• P

strut/braceclamping the connection in two halves around the existing primary structure

• Ware all fabricated and coated offsite.

The success of the joint relies on the clamping action around the existing vertical strut in the roof truss. To address this, the following was conducted to make provision for construction conditions:• Early site measuring of the 163CHS

existing struts was cond• An allowance for a UV resistant rubber

sleeve was made between the existing CHS outer diameter and the inner diameter of the clamp.

• TFclamping action on the 163CHS

• All TF bolts also used lwashers to assist in site QA.

• Refer to Figure clamp and strut/brace connection details used.

connections capacity (which is smaller the member), the joint would slip (whilemaintaining the joint TF new position 10mm offset whereby the bolting can then behave alsoas well. Therefore the connection can be said to have considerable redundancy in it.The 10mm deformation in the strut connections would also have associated deformations in the restrained However the order of these additional moment actions is insignificant relative to the length of accommodated.Refer to Figure strut/brace members, and refer to Figure for the connection details of the strut/braces.

The Strut/Brace DesignThe Structural Steel clamp adopted in detailed design is the element that allowed the works to progressfor the following considerations

It forms the connection of the struts/braces to the primary structure.Provides vertical clestrut/braceclamping the connection in two halves around the existing primary structureWith this scheme the clamps, struts/braces are all easilyfabricated and coated offsite.success of the joint relies on the clamping

action around the existing vertical strut in the roof truss. To address this, the following was conducted to make provision for construction conditions:

Early site measuring of the 163CHS existing struts was condAn allowance for a UV resistant rubber sleeve was made between the existing CHS outer diameter and the inner diameter of the clamp.TF bolting was again adopted to mobilize a clamping action on the 163CHSAll TF bolts also used lwashers to assist in site QA.Refer to Figure clamp and strut/brace connection details used.

ions capacity (which is smaller the member), the joint would slip (whilemaintaining the joint TF new position 10mm offset whereby the bolting can then behave alsoas well. Therefore the connection can be said to have considerable redundancy in it.The 10mm deformation in the strut connections would also have associated deformations in the restrained

owever the order of these additional ent actions is insignificant relative to

the length of Strut 1 and can be easily accommodated. Refer to Figure 6 for an elevation of the strut/brace members, and refer to Figure for the connection details of the strut/braces.

The Strut/Brace Designtructural Steel clamp adopted in

detailed design is the element that allowed the works to progress. The clamp for the following considerations

forms the connection of the struts/braces to the primary structure.

vertical clestrut/braces, while alsoclamping the connection in two halves around the existing primary structure

ith this scheme the clamps, struts/braces easily removable and able to be fully

fabricated and coated offsite.success of the joint relies on the clamping

action around the existing vertical strut in the roof truss. To address this, the following was conducted to make provision for construction

Early site measuring of the 163CHS existing struts was condAn allowance for a UV resistant rubber sleeve was made between the existing CHS outer diameter and the inner diameter of the clamp.

bolting was again adopted to mobilize a clamping action on the 163CHSAll TF bolts also used lwashers to assist in site QA.Refer to Figure 8 for and extract of the clamp and strut/brace connection details

ions capacity (which is smaller the member), the joint would slip (whilemaintaining the joint TF capacity) into a new position 10mm offset whereby the bolting can then behave alsoas well. Therefore the connection can be said to have considerable redundancy in it.The 10mm deformation in the strut connections would also have associated deformations in the restrained


trut 1 and can be easily

for an elevation of the strut/brace members, and refer to Figure for the connection details of the

The Strut/Brace Design tructural Steel clamp adopted in

detailed design is the element that allowed the he clamp design provided

for the following considerations: forms the connection of the struts/braces

to the primary structure. vertical cleats for the

also allowing for clamping the connection in two halves around the existing primary structure

ith this scheme the clamps, struts/braces removable and able to be fully

fabricated and coated offsite.success of the joint relies on the clamping


Early site measuring of the 163CHS existing struts was conducted by FEGL.An allowance for a UV resistant rubber sleeve was made between the existing CHS outer diameter and the inner diameter

bolting was again adopted to mobilize a clamping action on the 163CHSAll TF bolts also used load indicating washers to assist in site QA.

for and extract of the clamp and strut/brace connection details

ions capacity (which is smaller the member), the joint would slip (while

capacity) into a new position 10mm offset whereby the bolting can then behave also in single shear as well. Therefore the connection can be said to have considerable redundancy in it.The 10mm deformation in the strut connections would also have associated deformations in the restrained Strut 1



for an elevation of the strut/brace members, and refer to Figure for the connection details of the

tructural Steel clamp adopted in the detailed design is the element that allowed the

design provided

forms the connection of the struts/braces

ats for the new allowing for

clamping the connection in two halves around the existing primary structure.


fabricated and coated offsite. success of the joint relies on the clamping


Early site measuring of the 163CHS ucted by FEGL.

An allowance for a UV resistant rubber sleeve was made between the existing CHS outer diameter and the inner diameter

bolting was again adopted to mobilize a clamping action on the 163CHS.

oad indicating washers to assist in site QA.


ions capacity (which is smaller than the member), the joint would slip (while still

capacity) into a new position 10mm offset whereby the

in single shear as well. Therefore the connection can be said to have considerable redundancy in it.

connections would also have associated trut 1.



for an elevation of the strut/brace members, and refer to Figure 8

the detailed design is the element that allowed the

design provided

forms the connection of the struts/braces

clamping the connection in two halves .


success of the joint relies on the clamping action around the existing vertical strut in the roof truss. To address this, the following was conducted to make provision for construction

ucted by FEGL. An allowance for a UV resistant rubber sleeve was made between the existing CHS outer diameter and the inner diameter

bolting was again adopted to mobilize a

oad indicating


Figure

Figure To assess the influence of the stabilizing actions and clamping actions on the clamp parts as well

Figure 7 – Space

Figure 8 – Clamp detail drawing extractTo assess the influence of the stabilizing actions and clamping actions on the clamp parts as well

Space Gass Clamp Model

Clamp detail drawing extractTo assess the influence of the stabilizing actions and clamping actions on the clamp parts as well

ass Clamp Model


ass Clamp Model


ass Clamp Model

Clamp detail drawing extract To assess the influence of the stabilizing actions and clamping actions on the clamp parts as well

To assess the influence of the stabilizing actions and clamping actions on the clamp parts as well

as the existing structure, calculations were conducted by hand then verified by the use of a Space7). The findings following:• That the clamping load as well as action on

the existing 163CHS acceptable even in consideration of the existing loads in the CHS from uplift actions.

• That the loading verthe rubber sleeve

• That the clamp bolting to the existing strut had to be actions as when minimum tension and the clamp has rto deform, then the clamps take on significant load.

• To address even minor loading the clamneeded to be significantly stiffened in the detailed design, thereby taking the single clamp clamp methodology became topical due todifficulty

• The clamp in position and to transfer the vertical actions into the existing structure was relatively minor, again this mechanism had redundancy such that in the event of significant loading the clamps could deform while still maintaining their clamping capability.

• All TF bolts also used load indicating washers to assist in site QA.

The detailed design of the stadium wind strengthening ithe clamp and the strut. These only varied nominally by:• Length, for the struts versus the braces and

site measurement variations.• The single versus the double clamp that

took the braces.A last note on the clamps, due to the espaces on the clamp bolting stiffening angles, the clamps were hot dip galvanized initially. Top coating was via a 2 pot epoxy paint Therefore the clamps have a very long time before probable first maintenance is likely to be required. Howestiffeners that were likely to trap water were pitched at 7.5 degrees to the horizontal to actively shed water rather than retain it and the probable associated chloride laden deposits.

as the existing structure, calculations were conducted by hand then verified by the use of a

pace Gass model of the clamp (refer to Figure he findings

following: That the clamping load as well as action on the existing 163CHS acceptable even in consideration of the existing loads in the CHS from uplift actions. That the loading very sensitive to its support conditions (ie the rubber sleeveThat the clamp bolting to the existing strut had to be actions as when minimum tension and the clamp has rto deform, then the clamps take on significant load.To address even minor loading the clamneeded to be significantly stiffened in the detailed design, thereby taking the single clamp half clamp half methodology became topical due todifficulty manhandling of these The required clamp in position and to transfer the vertical actions into the existing structure was relatively minor, again this mechanism had redundancy such that in the event of significant loading the clamps could deform while still maintaining their clamping capability.All TF bolts also used load indicating washers to assist in site QA.

The detailed design of the stadium wind strengthening ithe clamp and the strut. These only varied nominally by:

Length, for the struts versus the braces and site measurement variations.The single versus the double clamp that took the braces.

A last note on the clamps, due to the espaces on the clamp bolting stiffening angles, the clamps were hot dip galvanized initially. Top coating was via a 2 pot epoxy paint

herefore the clamps have a very long time before probable first maintenance is likely to be required. Howestiffeners that were likely to trap water were pitched at 7.5 degrees to the horizontal to actively shed water rather than retain it and the probable associated chloride laden deposits.


s model of the clamp (refer to Figure he findings of this exercise raised the

That the clamping load as well as action on the existing 163CHS acceptable even in consideration of the existing loads in the CHS from uplift

That the loading distributiony sensitive to its support conditions (ie

the rubber sleeve and clamp stiffnessThat the clamp bolting to the existing strut had to be minimized closely to the design actions as when TFminimum tension and the clamp has rto deform, then the clamps take on significant load. To address even minor loading the clamneeded to be significantly stiffened in the detailed design, thereby taking the single

half weight to half weight to

methodology became topical due tomanhandling of these

required clamping load to keep the clamp in position and to transfer the vertical actions into the existing structure was relatively minor, again this mechanism had redundancy such that in the event of significant loading the clamps could deform while still maintaining their clamping capability. All TF bolts also used load indicating washers to assist in site QA.

The detailed design of the stadium wind strengthening included only two the clamp and the strut. These only varied

Length, for the struts versus the braces and site measurement variations.The single versus the double clamp that took the braces.


herefore the clamps have a very long time before probable first maintenance is likely to be required. However as an added measure all stiffeners that were likely to trap water were pitched at 7.5 degrees to the horizontal to actively shed water rather than retain it and the probable associated chloride laden deposits.


s model of the clamp (refer to Figure of this exercise raised the

That the clamping load as well as action on the existing 163CHS vertical strut acceptable even in consideration of the existing loads in the CHS from uplift

distribution y sensitive to its support conditions (ie

and clamp stiffnessThat the clamp bolting to the existing strut

minimized closely to the design TF bolting is torqued to

minimum tension and the clamp has rto deform, then the clamps take on

To address even minor loading the clamneeded to be significantly stiffened in the detailed design, thereby taking the single

weight to 28kg, and the double weight to 50kg. In

methodology became topical due tomanhandling of these

clamping load to keep the clamp in position and to transfer the vertical actions into the existing structure was relatively minor, again this mechanism had redundancy such that in the event of significant loading the clamps could deform while still maintaining their clamping

All TF bolts also used load indicating washers to assist in site QA.

The detailed design of the stadium wind ncluded only two components

the clamp and the strut. These only varied

Length, for the struts versus the braces and site measurement variations.The single versus the double clamp that


herefore the clamps have a very long time before probable first maintenance is likely to be

ver as an added measure all stiffeners that were likely to trap water were pitched at 7.5 degrees to the horizontal to actively shed water rather than retain it and the probable associated chloride laden deposits.



That the clamping load as well as action on vertical strut was

acceptable even in consideration of the existing loads in the CHS from uplift

the clamp was y sensitive to its support conditions (ie

and clamp stiffnessThat the clamp bolting to the existing strut

minimized closely to the design bolting is torqued to

minimum tension and the clamp has rto deform, then the clamps take on

To address even minor loading the clamneeded to be significantly stiffened in the detailed design, thereby taking the single

, and the double nstallation

methodology became topical due to manhandling of these weight

clamping load to keep the clamp in position and to transfer the vertical actions into the existing structure was relatively minor, again this mechanism had redundancy such that in the event of significant loading the clamps could deform while still maintaining their clamping

All TF bolts also used load indicating washers to assist in site QA.

The detailed design of the stadium wind components

the clamp and the strut. These only varied

Length, for the struts versus the braces and site measurement variations. The single versus the double clamp that

A last note on the clamps, due to the enclosed spaces on the clamp bolting stiffening angles, the clamps were hot dip galvanized initially. Top coating was via a 2 pot epoxy paint system

herefore the clamps have a very long time before probable first maintenance is likely to be

ver as an added measure all stiffeners that were likely to trap water were pitched at 7.5 degrees to the horizontal to actively shed water rather than retain it and the probable associated chloride laden deposits.



That the clamping load as well as action on was

acceptable even in consideration of the

the clamp was y sensitive to its support conditions (ie

and clamp stiffness). That the clamp bolting to the existing strut

minimized closely to the design bolting is torqued to

minimum tension and the clamp has room

To address even minor loading the clamps needed to be significantly stiffened in the detailed design, thereby taking the single

, and the double stallation

weights. clamping load to keep the

clamp in position and to transfer the vertical actions into the existing structure was relatively minor, again this mechanism had redundancy such that in the event of significant loading the clamps could deform

All TF bolts also used load indicating

components, the clamp and the strut. These only varied

Length, for the struts versus the braces and

The single versus the double clamp that

nclosed spaces on the clamp bolting stiffening angles, the clamps were hot dip galvanized initially. Top

system. herefore the clamps have a very long time

before probable first maintenance is likely to be ver as an added measure all

stiffeners that were likely to trap water were pitched at 7.5 degrees to the horizontal to actively shed water rather than retain it and the probable associated chloride laden deposits.

Therefore the coating system on the clamp more durable that the surrounding systems, they can also be locally removed to be recoated if required.We considered using the bolting arrangement to fit the clamp and connect the strut, but found that the need for high friction in the strut connectionwere incompatible or overly stressed the clamp.Significant interaction was conducted between Beca and FEGL during the entire detailed designfabrication stages ultimately derivduring the construction

Figure

Figure

Therefore the coating system on the clamp more durable that the surrounding systems, they can also be locally removed to be recoated if required. We considered using the bolting arrangement to fit the clamp and connect the strut, but found that the need for high friction in the strut connection and tolerance in the clamp fitting were incompatible or overly stressed the clamp.Significant interaction was conducted between Beca and FEGL during the entire detailed design, the workshop drawingsfabrication stages ultimately derivduring the construction

Figure 9

Figure 10

Therefore the coating system on the clamp more durable that the surrounding systems, they can also be locally removed to be recoated if

We considered using the bolting arrangement to fit the clamp and connect the strut, but found that the need for high friction in the strut

and tolerance in the clamp fitting were incompatible or overly stressed the clamp.Significant interaction was conducted between Beca and FEGL during the entire detailed

the workshop drawingsfabrication stages ultimately derivduring the construction

– FEGL Workshop ISO of Clamp

10 – FEGL Shop Drawing of Craned Access Platforms




the workshop drawingsfabrication stages ultimately derivduring the construction stage.

FEGL Workshop ISO of Clamp

FEGL Shop Drawing of Craned Access Platforms




the workshop drawings, testingfabrication stages ultimately deriving ben

stage.


FEGL Shop Drawing of Craned Access Platforms

Therefore the coating system on the clamp is more durable that the surrounding systems, they can also be locally removed to be recoated if



, testing and benefits


FEGL Shop Drawing of Craned

more durable that the surrounding systems, they

We considered using the bolting arrangement to

were incompatible or overly stressed the clamp.

FEGL Shop Drawing of Craned

6. CONSTRUCTION

The workshop drawing, fabrication and coatings and installation methodologies derived mainly from FEGL andproduct in the best way they could. Their experience and depth in combination with their active interaction in the workshop and interactive discussion of detail and works methodology led to many benefits for the projectare as follows:Workshop Drawings:All shop drawings for every plate and element were produced in Steel Pro. They included complete material measured variations.sample100% prefabrication and coating:All elements were able to be shop fabricated. Therefore weld and coating quality was high and able to be fully inspected. No rework was required on this project.Workshop testing of fitA mockupdeveloped in the workshop by FEGLallowing a test fit scenario prior to the elements getting to site. Refer to the shop assemblyBespoke access platforms:Due to accessing the roof, FEGL developed bespoke access/work platforms that spanned purlins and allowed discrete work areas at the clamps to be worked safeable to be lifted by crane next very rapidly. Refer to extract of the shop drawing of these platformsClamp lifting jigs:Clamps were efficiently fitted by use of a set of bespoke steel plate lifting jigs that allowed the clamps to be lowereseparated above the top chord (lowered and fitted into position around the vertical 163CHS. The crane could then finely adjust the clamp heights prior to the fitting bolts being tightened to fit the clamp in place. Ofitted the jig/crane assemble would then bring up the next one for the next joint creating a reliable, repeatable, rapid process. Refer to a sample of the shop drawing of this jig.Load indicator washers:Load indicator washers were adoptall TF bolting, specifically “Squirter Washers”They are so called due to the washers having

CONSTRUCTIONThe workshop drawing, fabrication and coatings and installation methodologies derived mainly from FEGL andproduct in the best way they could. Their experience and depth in combination with their active interaction in the workshop and interactive discussion of detail and works methodology led to many benefits for the project. A likely nonare as follows: Workshop Drawings:All shop drawings for every plate and element were produced in Steel Pro. They included complete material measured variations.sample isometric shop drawing of the clamp.100% prefabrication and coating:

ll elements were able to be shop fabricated. Therefore weld and coating quality was high and able to be fully inspected. No rework was required on this project.Workshop testing of fit

mockup of the braced assemble was developed in the workshop by FEGLallowing a test fit scenario prior to the elements getting to site. Refer to the shop assemblyBespoke access platforms:Due to the inaccessibility and safety concerns of accessing the roof, FEGL developed bespoke access/work platforms that spanned purlins and allowed discrete work areas at the clamps to be worked safely. These platforms, 3 in total were able to be lifted by crane next very rapidly. Refer to extract of the shop drawing of these platformsClamp lifting jigs:Clamps were efficiently fitted by use of a set of bespoke steel plate lifting jigs that allowed the clamps to be lowereseparated above the top chord (lowered and fitted into position around the vertical 163CHS. The crane could then finely adjust the clamp heights prior to the fitting bolts being tightened to fit the clamp in place. Ofitted the jig/crane assemble would then bring up the next one for the next joint creating a reliable, repeatable, rapid process. Refer to a sample of the shop drawing of this jig.Load indicator washers:Load indicator washers were adoptall TF bolting, specifically “Squirter Washers”

hey are so called due to the washers having

CONSTRUCTIONThe workshop drawing, fabrication and coatings and installation methodologies derived mainly from FEGL and their aim to provide the best product in the best way they could. Their experience and depth in combination with their active interaction in the workshop and interactive discussion of detail and works methodology led to many benefits for

likely non-

Workshop Drawings: All shop drawings for every plate and element were produced in Steel Pro. They included complete material take offs, weights and site measured variations. Refer to

isometric shop drawing of the clamp.100% prefabrication and coating:

ll elements were able to be shop fabricated. Therefore weld and coating quality was high and able to be fully inspected. No rework was required on this project. Workshop testing of fit

of the braced assemble was developed in the workshop by FEGLallowing a test fit scenario prior to the elements getting to site. Refer to Fthe shop assembly Bespoke access platforms:

the inaccessibility and safety concerns of accessing the roof, FEGL developed bespoke access/work platforms that spanned purlins and allowed discrete work areas at the clamps to be

y. These platforms, 3 in total were able to be lifted by crane next very rapidly. Refer to extract of the shop drawing of these platformsClamp lifting jigs: Clamps were efficiently fitted by use of a set of bespoke steel plate lifting jigs that allowed the clamps to be lowered by a spreader beam, separated above the top chord (lowered and fitted into position around the vertical 163CHS. The crane could then finely adjust the clamp heights prior to the fitting bolts being tightened to fit the clamp in place. Ofitted the jig/crane assemble would then bring up the next one for the next joint creating a reliable, repeatable, rapid process. Refer to a sample of the shop drawing of this jig.Load indicator washers:Load indicator washers were adoptall TF bolting, specifically “Squirter Washers”


CONSTRUCTION: The workshop drawing, fabrication and coatings and installation methodologies derived mainly

their aim to provide the best product in the best way they could. Their experience and depth in combination with their active interaction in the Safety In Design workshop and interactive discussion of detail and works methodology led to many benefits for

-complete list of these

All shop drawings for every plate and element were produced in Steel Pro. They included

ake offs, weights and site Refer to Figure


ll elements were able to be shop fabricated. Therefore weld and coating quality was high and able to be fully inspected. No rework was

Workshop testing of fits and bolt tensioning:

of the braced assemble was developed in the workshop by FEGLallowing a test fit scenario prior to the elements

Figure 12

Bespoke access platforms: the inaccessibility and safety concerns of

accessing the roof, FEGL developed bespoke access/work platforms that spanned purlins and allowed discrete work areas at the clamps to be

y. These platforms, 3 in total were able to be lifted by crane from one position to the next very rapidly. Refer to Figure extract of the shop drawing of these platforms

Clamps were efficiently fitted by use of a set of bespoke steel plate lifting jigs that allowed the

d by a spreader beam, separated above the top chord (Slowered and fitted into position around the vertical 163CHS. The crane could then finely adjust the clamp heights prior to the fitting bolts being tightened to fit the clamp in place. Ofitted the jig/crane assemble would then bring up the next one for the next joint creating a reliable, repeatable, rapid process. Refer to a sample of the shop drawing of this jig.Load indicator washers: Load indicator washers were adoptall TF bolting, specifically “Squirter Washers”


The workshop drawing, fabrication and coatings and installation methodologies derived mainly

their aim to provide the best product in the best way they could. Their experience and depth in combination with their

n Design (workshop and interactive discussion of detail and works methodology led to many benefits for

complete list of these


ake offs, weights and site igure 9 for a



s and bolt tensioning:of the braced assemble was

developed in the workshop by FEGL, thereby allowing a test fit scenario prior to the elements

12 for photos of


y. These platforms, 3 in total were from one position to the

igure 10 for anextract of the shop drawing of these platforms


d by a spreader beam, Strut 1) and then

lowered and fitted into position around the vertical 163CHS. The crane could then finely adjust the clamp heights prior to the fitting bolts being tightened to fit the clamp in place. Ofitted the jig/crane assemble would then bring up the next one for the next joint creating a reliable, repeatable, rapid process. Refer to Figure a sample of the shop drawing of this jig.

Load indicator washers were adopted for use on all TF bolting, specifically “Squirter Washers”


The workshop drawing, fabrication and coatings and installation methodologies derived mainly

their aim to provide the best

experience and depth in combination with their (SID)

workshop and interactive discussion of detail and works methodology led to many benefits for

complete list of these


ake offs, weights and site for a

isometric shop drawing of the clamp.


s and bolt tensioning:

, thereby allowing a test fit scenario prior to the elements

for photos of


y. These platforms, 3 in total were from one position to the

n extract of the shop drawing of these platforms


d by a spreader beam, trut 1) and then

lowered and fitted into position around the vertical 163CHS. The crane could then finely adjust the clamp heights prior to the fitting bolts being tightened to fit the clamp in place. Once fitted the jig/crane assemble would then bring up the next one for the next joint creating a reliable,

igure 11 for

ed for use on all TF bolting, specifically “Squirter Washers”.


“buttons” that deform flat at the appropriate bolt pretension and “squirt” out an indicator mark of paint. These allow a rapid review of tensioning completion to allow work to progresswas found in conjunction with FEGL that on the clamps with minor deformation (due to tensioning of the clamp bolts), bolt nuts do not activate the squirter buttons if the nut is not completely true. This canof the TF bolts in an attempt to activate the washers. This was observed testing stage (refer doing a parallel check using Thereforeconfirm a level of tensioning had been achieved, but not necessarily the final tension. Alsoclamp bolting to the existing strut did not critically need to be at full tensiontorque limits were seen as conservative in tcase to test on the lower side of the minimumsdue to them acting in tension as well as being pretensioned.Friction Grip bolting:The use of TF bolting in both shear and in tension allowed the site assembldimensionally stable structure with anabundance of construction tolerance, therefore avoiding lost time and roof top site works.

Figure

“buttons” that deform flat at the appropriate bolt pretension and “squirt” out an indicator mark of paint. These allow a rapid review of tensioning completion to allow work to progresswas found in conjunction with FEGL that on the clamps with minor deformation (due to tensioning of the clamp bolts), bolt nuts do not activate the squirter buttons if the nut is not completely true. This canof the TF bolts in an attempt to activate the washers. This was observed testing stage (refer doing a parallel check using Therefore, in this instanceconfirm a level of tensioning had been achieved, but not necessarily the final tension. Alsoclamp bolting to the existing strut did not critically need to be at full tensiontorque limits were seen as conservative in tcase to test on the lower side of the minimumsdue to them acting in tension as well as being pretensioned.Friction Grip bolting:The use of TF bolting in both shear and in tension allowed the site assembldimensionally stable structure with anabundance of construction tolerance, therefore avoiding lost time and roof top site works.

Figure 11

“buttons” that deform flat at the appropriate bolt pretension and “squirt” out an indicator mark of paint. These allow a rapid review of tensioning completion to allow work to progresswas found in conjunction with FEGL that on the clamps with minor deformation (due to tensioning of the clamp bolts), bolt nuts do not activate the squirter buttons if the nut is not completely true. This canof the TF bolts in an attempt to activate the washers. This was observed testing stage (refer Fdoing a parallel check using

in this instanceconfirm a level of tensioning had been achieved, but not necessarily the final tension. Alsoclamp bolting to the existing strut did not critically need to be at full tensiontorque limits were seen as conservative in tcase to test on the lower side of the minimumsdue to them acting in tension as well as being pretensioned. Friction Grip bolting:The use of TF bolting in both shear and in tension allowed the site assembldimensionally stable structure with anabundance of construction tolerance, therefore avoiding lost time and roof top site works.

11 – FEGL Shop Drawing ofInstallation Jigs

“buttons” that deform flat at the appropriate bolt pretension and “squirt” out an indicator mark of paint. These allow a rapid review of tensioning completion to allow work to progresswas found in conjunction with FEGL that on the clamps with minor deformation (due to tensioning of the clamp bolts), bolt nuts do not activate the squirter buttons if the nut is not completely true. This can lead to over tightening of the TF bolts in an attempt to activate the washers. This was observed during the mockup

Figure 12) doing a parallel check using a

in this instance, they were useful to confirm a level of tensioning had been achieved, but not necessarily the final tension. Alsoclamp bolting to the existing strut did not critically need to be at full tensiontorque limits were seen as conservative in tcase to test on the lower side of the minimumsdue to them acting in tension as well as being

Friction Grip bolting: The use of TF bolting in both shear and in tension allowed the site assembldimensionally stable structure with anabundance of construction tolerance, therefore avoiding lost time and roof top site works.

FEGL Shop Drawing ofInstallation Jigs

“buttons” that deform flat at the appropriate bolt pretension and “squirt” out an indicator mark of paint. These allow a rapid review of tensioning completion to allow work to progress. Hwas found in conjunction with FEGL that on the clamps with minor deformation (due to tensioning of the clamp bolts), bolt nuts do not activate the squirter buttons if the nut is not

lead to over tightening of the TF bolts in an attempt to activate the

during the mockup igure 12) when FEGL were

a torque wrench. they were useful to

confirm a level of tensioning had been achieved, but not necessarily the final tension. Alsoclamp bolting to the existing strut did not critically need to be at full tension. Therefore torque limits were seen as conservative in tcase to test on the lower side of the minimumsdue to them acting in tension as well as being

The use of TF bolting in both shear and in tension allowed the site assembly of a dimensionally stable structure with an abundance of construction tolerance, therefore avoiding lost time and roof top site works.

FEGL Shop Drawing ofInstallation Jigs

“buttons” that deform flat at the appropriate bolt pretension and “squirt” out an indicator mark of paint. These allow a rapid review of tensioning

. However it was found in conjunction with FEGL that on the clamps with minor deformation (due to tensioning of the clamp bolts), bolt nuts do not activate the squirter buttons if the nut is not

lead to over tightening of the TF bolts in an attempt to activate the

during the mockup when FEGL were torque wrench.

they were useful to confirm a level of tensioning had been achieved, but not necessarily the final tension. Also, the clamp bolting to the existing strut did not

herefore torque limits were seen as conservative in this case to test on the lower side of the minimums, due to them acting in tension as well as being

The use of TF bolting in both shear and in a

abundance of construction tolerance, therefore avoiding lost time and roof top site works.

FEGL Shop Drawing of Clamp

“buttons” that deform flat at the appropriate bolt

owever it was found in conjunction with FEGL that on the

lead to over tightening

during the mockup when FEGL were

confirm a level of tensioning had been achieved,

Figure

7. PROJECT RESULTS:From review of the project at completion the following can be surmised:

•

•

•

• • •

• •

•

Figure 12

PROJECT RESULTS:From review of the project at completion the following can be surmised:

The design intent achieved a robust strengthening schemeinvolvement, enabled by the clientprocess from the outset

A safe construction process was established and followedbespoke access and installation assemblies

The combination of a considered design and construction methodology meant a quick, efficient construction.

Offsite work also protected the existing structure and roof from site work related damage. The strengthening is fully removable High quality steel products were achieved by workshop fabrication and painting in combination

with experienced contractors with formal quality assurance practices (FEGL). 40% cost reduction from estimates Functional

100m transverse Subsequent installation

engineer

12 – Photos from FEGL’s workshop depicting the mock assembly of components

PROJECT RESULTS:From review of the project at completion the following can be surmised:

esign intent achieved a robust strengthening schemeinvolvement, enabled by the clientprocess from the outsetA safe construction process was established and followedbespoke access and installation assemblies

e combination of a considered design and construction methodology meant a quick, efficient construction. Offsite work also protected the existing structure and roof from site work related damage.The strengthening is fully removable

quality steel products were achieved by workshop fabrication and painting in combination experienced contractors with formal quality assurance practices (FEGL).

40% cost reduction from estimates Functional installation 100m transverse Subsequent installation engineer’s site visits, albeit with improved access to the work stations.

Photos from FEGL’s workshop depicting the mock assembly of components

PROJECT RESULTS: From review of the project at completion the following can be surmised:

esign intent achieved a robust strengthening schemeinvolvement, enabled by the clientprocess from the outset. A safe construction process was established and followedbespoke access and installation assemblies

e combination of a considered design and construction methodology meant a quick, efficient

Offsite work also protected the existing structure and roof from site work related damage.The strengthening is fully removable


40% cost reduction from estimates installation occurred at

100m transverse long truss.Subsequent installation of the same system

s site visits, albeit with improved access to the work stations.


From review of the project at completion the following can be surmised:

esign intent achieved a robust strengthening schemeinvolvement, enabled by the client



Offsite work also protected the existing structure and roof from site work related damage.The strengthening is fully removable


40% cost reduction from estimates occurred attruss. Therefore contractor risk exposure time was short.

of the same system s site visits, albeit with improved access to the work stations.


From review of the project at completion the following can be surmised:esign intent achieved a robust strengthening scheme

involvement, enabled by the client (TRC/NPDC)



Offsite work also protected the existing structure and roof from site work related damage.The strengthening is fully removable and maintainable


40% cost reduction from estimates based onoccurred at 3.5 working days

Therefore contractor risk exposure time was short.of the same system



From review of the project at completion the following can be surmised:esign intent achieved a robust strengthening scheme

NPDC) who was able to appreciate the benefits of this

A safe construction process was established and followedbespoke access and installation assemblies. No accidents occurred during this project.


Offsite work also protected the existing structure and roof from site work related damage.and maintainable


based on conventional connection methodology.3.5 working days

Therefore contractor risk exposure time was short.of the same system on the opposing stand was fully installed betw



From review of the project at completion the following can be surmised:esign intent achieved a robust strengthening scheme through collaborative early contractor

who was able to appreciate the benefits of this

A safe construction process was established and followed through by the contractor including No accidents occurred during this project.


Offsite work also protected the existing structure and roof from site work related damage.and maintainable.


conventional connection methodology.3.5 working days for a total of

Therefore contractor risk exposure time was short.on the opposing stand was fully installed betw



From review of the project at completion the following can be surmised: through collaborative early contractor

who was able to appreciate the benefits of this

through by the contractor including No accidents occurred during this project.


Offsite work also protected the existing structure and roof from site work related damage.


conventional connection methodology.a total of 4T of structural steel over a




through collaborative early contractor who was able to appreciate the benefits of this





conventional connection methodology.T of structural steel over a








quality steel products were achieved by workshop fabrication and painting in combination

conventional connection methodology. T of structural steel over a

Therefore contractor risk exposure time was short. on the opposing stand was fully installed betw



through by the contractor including



quality steel products were achieved by workshop fabrication and painting in combination

T of structural steel over a

on the opposing stand was fully installed between

through collaborative early contractor

C. Twaddle and R. Van Bergen Beca Ltd, New Zealand Fitzroy ... Innovations... · Beca Ltd, New...

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