Technical Note - TN 006: 2016 · Technical Note - TN 006: 2016 . Subject: Update to live load in T...

Technical Note - TN 006: 2016

© State of NSW through Transport for NSW of 3

Sup

erse

ded

by T

HR

CI 1

2008

ST

v2.0

, 25/

06/2

018


Subject: Update to live load in T HR CI 12008 ST Load Rating of Underbridges

Issued date: 01 February 2016

Effective date: 01 February 2016

For queries regarding this document [email protected]

www.asa.transport.nsw.gov.au

This technical note is issued by the Asset Standards Authority to incorporate the following

updates to T HR CI 12008 ST Load Rating of Underbridges version 1.0. The update provides

clarification of the heavy coal (HC) and main line freight (MF) train consists used when assessing

TfNSW underbridges.

The content of the standard shall be amended as follows:

9.1 Live load Replace the first two bullet points with the following:

• Heavy Coal (HC) – based on 5/165 tonne locomotives plus 120 tonne coal wagons

• Main Line freight (MF) – based on 5/132 tonne locomotives plus 100 tonne wagons

Replace the last paragraph with the following:

HC train consist loading shall be considered for assessments carried out on those

underbridges on the Main North Line between Woodville Junction and Vales Point Junction.

Insert the following note after the final paragraph:

Note: In the previous RailCorp version of this standard, both HC and MF contained three

locomotives.

Appendix A Loading diagrams Replace with the following:

mailto:[email protected]

mailto:[email protected]

http://www.asa.transport.nsw.gov.au/



Sup

erse

ded

by T

HR

CI 1

2008

ST

v2.0

, 25/

06/2

018 Appendix A Loading diagrams

Figure 2 contains a diagrammatic representation of the train consists listed in Section 9.1 of this document.

The overall vehicle length dimensions shown are measured to the vehicle coupler pulling faces in millimetres.

Figure 2 – Loading diagrams



Authorisation:

Technical content prepared by

Checked and approved by

Interdisciplinary coordination checked by

Authorised for release

Signature

Date

Name Malcolm Peake Richard Hitch John Paff Graham Bradshaw

Position Senior Engineer Structures

Lead Civil Engineer A/Chief Engineer Rail Director Network Standards and Services

Sup

erse

ded

by T

HR

CI 1

2008

ST

v2.0

, 25/

06/2

018

Load Rating of Underbridges

T HR CI 12008 ST

Standard

Version 1.0

Issued date: 21 October 2015

Important Warning This document is one of a set of standards developed solely and specifically for use on public transport assets which are vested in or owned, managed, controlled, commissioned or funded by the NSW Government, a NSW Government agency or a Transport Agency (as defined in the Asset Standards Authority Charter). It is not suitable for any other purpose. You must not use or adapt it or rely upon it in any way unless you are authorised in writing to do so by a relevant NSW Government agency. If this document forms part of a contract with, or is a condition of approval by a NSW Government agency, use of the document is subject to the terms of the contract or approval. This document is uncontrolled when printed or downloaded. Users should exercise their own skill and care in the use of the document. This document may not be current. Current standards are available for download from the Asset Standards Authority website at www.asa.transport.nsw.gov.au. © State of NSW through Transport for NSW

Sup

erse

ded

by T

HR

CI 1

2008

ST

v2.0

, 25/

06/2

018

T HR CI 12008 ST Load Rating of Underbridges

Version 1.0 Issued date: 21 October 2015

Standard governance

Owner: Lead Civil Engineer, Asset Standards Authority

Authoriser: Chief Engineer Rail, Asset Standards Authority

Approver: Executive Director, Asset Standards Authority on behalf of the ASA Configuration Control Board

Document history

Version Summary of Changes

1.0 First issue

For queries regarding this document, please email the ASA at [email protected] or visit www.asa.transport.nsw.gov.au

© State of NSW through Transport for NSW

Sup

erse

ded

by T

HR

CI 1

2008

ST

v2.0

, 25/

06/2

018



Preface The Asset Standards Authority (ASA) is an independent unit within Transport for NSW (TfNSW)

and is the network design and standards authority for defined NSW transport assets.

The ASA is responsible for developing engineering governance frameworks to support industry

delivery in the assurance of design, safety, integrity, construction, commissioning and

maintenance of transport assets for the whole asset life cycle. In order to achieve this, the ASA

effectively discharges obligations as the authority for various technical, process, and planning

matters across the asset life cycle.

The ASA collaborates with industry using stakeholder engagement activities to assist in

achieving its mission. These activities help align the ASA to broader government expectations

of making it clearer, simpler, and more attractive to do business within the NSW transport

industry, allowing the supply chain to deliver safe, efficient, and competent transport services.

The ASA develops, maintains, controls, and publishes a suite of standards and other

documentation for transport assets of TfNSW. Further, the ASA ensures that these standards

are performance-based to create opportunities for innovation and improve access to a broader

competitive supply chain.

This standard specifies the technical requirements for assessments performed on underbridges

on the TfNSW heavy rail network. This standard has been developed from RailCorp standard

ESC 301 Load Rating of Underbridges, Version 2.3.

This standard is a first issue.

© State of NSW through Transport for NSW Page 3 of 24

Sup

erse

ded

by T

HR

CI 1

2008

ST

v2.0

, 25/

06/2

018



Foreword

This standard is intended to be used by competent personnel engaged in the provision of

services relating to rail infrastructure. Compliance with the requirements in this standard will not,

by itself, be sufficient to ensure that satisfactory outcomes will be produced. Personnel

providing services based on the standard need to bring appropriate expertise to the matters

under consideration.

In addition to the requirements of this standard, asset decisions shall take into account the life

cycle cost considerations specified in T MU AM 01001 ST Life Cycle Costing.

If, when using the standard, it is considered that the intent of stated requirements is not clear, a

clarification shall be sought from the ASA.


Sup

erse

ded

by T

HR

CI 1

2008

ST

v2.0

, 25/

06/2

018



Table of contents 1. Introduction .............................................................................................................................................. 6

2. Purpose .................................................................................................................................................... 6 2.1. Scope ..................................................................................................................................................... 6 2.2. Application ............................................................................................................................................. 6

3. Reference documents ............................................................................................................................. 7

4. Terms and definitions ............................................................................................................................. 9

5. General requirements ........................................................................................................................... 10

6. Desk study .............................................................................................................................................. 11

7. Bridge inspection .................................................................................................................................. 11

8. Capacity assessment ............................................................................................................................ 12 8.1. Loss of structural section ..................................................................................................................... 12 8.2. Material strength .................................................................................................................................. 13

9. Loads ...................................................................................................................................................... 15 9.1. Live load............................................................................................................................................... 15 9.2. Nosing load .......................................................................................................................................... 16 9.3. Wind load ............................................................................................................................................. 16 9.4. Earthquake load ................................................................................................................................... 16

10. Load effects ............................................................................................................................................ 16 10.1. Load factors ..................................................................................................................................... 16 10.2. Dynamic load allowance .................................................................................................................. 17

11. Wind and sway bracing ......................................................................................................................... 17

12. Fatigue .................................................................................................................................................... 17

13. Reporting ................................................................................................................................................ 18 13.1. Wrought iron test results .................................................................................................................. 18 13.2. Wind and sway bracing .................................................................................................................... 19 13.3. Executive summary ......................................................................................................................... 19 13.4. Engineering details .......................................................................................................................... 19 13.5. Appendices ...................................................................................................................................... 19

Appendix A Loading diagrams .............................................................................................................. 20

Appendix B Bridge load rating executive summary table – sample layout ...................................... 21

Appendix C Bridge load rating engineering assessment summary table – sample layout ............ 22

Appendix D Suggested reading ............................................................................................................ 24


Sup

erse

ded

by T

HR

CI 1

2008

ST

v2.0

, 25/

06/2

018



1. Introduction An underbridge is a bridge which supports a track or tracks that pass over roadways, pathways,

flood plains, rivers, other tracks and the like. Underbridges can include viaducts, flyovers,

culvert structures and pedestrian subways.

Bridges have a typical design life of 100 years. The load carrying capacity of a bridge can vary

over time due to structural deficiencies. These deficiencies include, but are not limited to, steel

corrosion and concrete spalling.

The need to perform an assessment of an underbridge can also arise from impact, flood or fire

damage sustained by the structure.

The need for an underbridge to carry different loading across the life cycle also varies as new

rolling stock is introduced to the network.

The load rating of an underbridge may additionally change as standards change over the life of

the asset.

2. Purpose The purpose of this document is to provide the technical requirements to facilitate load ratings

and fatigue assessments to be performed for underbridges on the TfNSW heavy rail network.

2.1. Scope This document specifies the technical requirements for load ratings performed on underbridges

on the TfNSW heavy rail network. As new and as is load ratings are considered at both ultimate

and serviceability limit states.

This document supplements the requirements of AS 5100.7 Bridge design Part 7: Rating of

existing bridges.

Where a conflict is found to exist between the requirements of AS 5100.7 and this standard, the

requirements of this standard shall take precedence.

2.2. Application The requirements of this document apply to the assessment of existing underbridges on the

TfNSW heavy rail network. For as is load ratings, the consideration of underbridge modifications

and strengthening works which have been constructed shall be included as part of the

assessment.

This standard applies to all parties involved in performing underbridge assessments on the

TfNSW heavy rail network.


Sup

erse

ded

by T

HR

CI 1

2008

ST

v2.0

, 25/

06/2

018



3. Reference documents The following documents are cited in the text. For dated references, only the cited edition

applies. For undated references, the latest edition of the referenced document applies.

International standards

ASTM E3 - 11 Standard guide for preparation of metallographic specimens

ASTM E384 Standard test method for Knoop and Vickers hardness of material

BS 7608 Guide to fatigue design and assessment of steel products

EN 1993- Eurocode 3: Design of steel structures

EN 1993-1-9: Design of steel structures – Part 1-9 Fatigue

ISO 12696 Cathodic protection of steel in concrete

Australian standards

AS 1012 Methods of testing concrete

AS 1170 Structural design actions

AS 13822 Basis for design of structures – Assessment of existing structures

AS 1391 Metallic Materials – Tensile testing at ambient temperature

AS 1816 Metallic materials

AS 3600 Concrete structures

AS 5100 Bridge Design

AS 5100.1 Bridge design Part 1: Scope and general principles

AS 5100.2 Bridge design Part 2: Design loads

AS 5100.5 Bridge design Part 5: Concrete

AS 5100.6 Bridge design Part 6: Steel and composite construction concrete

AS 5100.7 Bridge design Part 7: Rating of existing bridges

Transport for NSW standards

ESC 100 Civil Technical Maintenance Plan

ESC 302 Structures Defect Limits

ESC 300 Structures System

TMC 300 Structures General

TMC 301 Structures Examination

TMC 305 Structures Assessment © State of NSW through Transport for NSW Page 7 of 24

Sup

erse

ded

by T

HR

CI 1

2008

ST

v2.0

, 25/

06/2

018



T MU AM 01001 ST Life Cycle Costing

TS 10760 Guide to interpretation of organisational role and process references in RailCorp

standards

TS 10760 SMS Interpretation guide RailCorp SMS references within RailCorp engineering

standards

TS 10762 Legacy RailCorp Standards Interpretation

TS TOC 1 Train Operating Conditions (TOC) Manual – General Instructions

Other reference documents

Design Manual for Roads and Bridges, Volume 3, BA 16/97 - The Assessment of Highway

Bridges and Structures

Design Manual for Roads and Bridges, Volume 3, BD 21/01 - The Assessment of Highway

Bridges and Structures

Design Manual for Roads and Bridges, Volume 3, BD 61/10 – The Assessment of Composite

Highways Bridges and Structures


Sup

erse

ded

by T

HR

CI 1

2008

ST

v2.0

, 25/

06/2

018



4. Terms and definitions The following terms and definitions apply in this document:

AEO Authorised Engineering Organisation; means a legal entity (which may include a Transport

Agency as applicable) to whom the ASA has issued an ASA Authorisation.

ASA Asset Standards Authority

DLA dynamic load allowance

filler (encased) beam rolled or built-up steel or iron sections that act in conjunction with a

concrete slab and which are contained within the slab or with slab surfaces flush with one or

both flanges

jack arch rolled or built-up steel or iron sections separated by concrete, stone or brick arches

supported by the lower flanges, generally with loose fill or concrete fill above

limit states are classified as either ultimate or serviceability in accordance with AS 5100.1

MEXE Military Engineering Experimental Establishment

MEXE analysis an empirical method for the assessment of a masonry arch bridge

TfNSW Transport for New South Wales

underbridge assessment is the sequential and multi-stage process which results in the

establishment of as is and as new load ratings for an underbridge. An estimate of the remaining

fatigue life of the underbridge is also a required deliverable of the process.


Sup

erse

ded

by T

HR

CI 1

2008

ST

v2.0

, 25/

06/2

018



5. General requirements All existing underbridges shall be assigned as new and as is load ratings.

Load rating and fatigue assessment shall be carried out in accordance with AS 5100.

The underbridge assessment process for assessing the load rating and fatigue assessment of

underbridges is a sequential and multi-stage process as outlined in Figure 1.

Desk study

Bridge inspection

Capacity assessment

Load effects

Fatigue

Load rating calculation

Report


Figure 1 – Process for the assessment of load rating and fatigue for underbridges

The required outcome of this process is the calculation of both an as new load rating and an as

is load rating for the underbridge being assessed. An estimate of the remaining fatigue life of

the underbridge is also a required outcome.

The as new load rating is based on an inspection and determination of load carrying capacity of

a structure based on the constituent components of the bridge being in new condition.

The as is load rating is based on an inspection and determination of load carrying capacity of a

structure based on the existing condition of the components of the bridge.

As new and as is load ratings are considered at both ultimate and serviceability limit states in

accordance with AS 5100.1 Bridge design Part 1: Scope and general principles.

All load carrying bridge components and connections shall be load rated.

The naming of bridge components shall be in accordance with ESC 300 Structures System.

Sup

erse

ded

by T

HR

CI 1

2008

ST

v2.0

, 25/

06/2

018



6. Desk study Prior to undertaking the inspection of an underbridge, all existing information pertaining to the

structure shall be collected and reviewed. This data shall include, but not be limited to, the

following:

• as-built drawings

• drawings for strengthening or maintenance works which have been carried out

• previous inspection reports

• the results of any prior structural testing

• results of any prior geotechnical investigations

• historical standards used in design

• all other relevant data

The purpose of the desk study is for the AEO to identify what information shall be determined

from the inspection. This information may include required testing on the structure. The desk

study shall also identify which components of the underbridge require particular attention during

the inspection.

7. Bridge inspection A load rating shall not be carried out until either a level 2 or level 3 inspection has been

performed on the underbridge.

A level 2 inspection is a detailed inspection where the condition of every accessible component

is visually rated and recorded as a minimum and which is undertaken in close proximity to the

component.

A level 3 inspection is a detailed engineering assessment undertaken by a professional

engineer on an as needed basis to investigate the structural integrity of a bridge and its

components.

The inspection shall verify the form and accuracy of construction together with the nature and

condition of the structural components. The inspection shall include, but is not limited to, the

following:

• determination of all dimensions needed to calculate nominal dead and superimposed dead

loadings

• determination of the position of the track and tracks relative to the structure

• determination of all parameters required to determine the strength of members


Sup

erse

ded

by T

HR

CI 1

2008

ST

v2.0

, 25/

06/2

018



• determination of defects such as spalling, corrosion, settlement, impact damage, flood

damage and defective material

• determination of the extent and location of any section loss or defects

• determination of condition and location of all bearings

• determination of condition of all movement joints

The inspection shall also include verification of any strengthening or maintenance works which

have been implemented since the underbridge was commissioned by TfNSW.

8. Capacity assessment The structural capacities for both as new and as is load ratings shall be calculated in

accordance with AS 5100 Bridge Design and the requirements of this standard.

The structural capacity for jack arch or filler (encased) beam underbridges shall be established

in accordance with BD 21/01, The Assessment of Highway Bridges and Structures, BA 16/97,

The Assessment of Highway Bridges and Structures and BD 61/10, The Assessment of

Composite Highway Bridges and Structures.

The inspection and structural capacity establishment for masonry arch underbridges on the

TfNSW heavy rail network, including modified Military Engineering Experimental Establishment

(MEXE) analysis, shall be established in accordance with BD 21/01, The Assessment of

Highway Bridges and Structures.

Capacity assessment shall take into account capacity reduction factors and material factors.

Cast iron bridge components shall be assessed using the working stress method. For the

assessment of any cast iron underbridge component, reference shall be made to specialist

literature.

8.1. Loss of structural section For as is load ratings, the adoption of reduced strength arising from section loss shall be clearly

stated and justified in a load rating report.

Where as is ratings are based on qualitative defect descriptions from inspection reports, the

losses stated in Table 1 shall be used:

Table 1 – Loss of structural section

Loss level Losses as a percentage of thickness

Minor Not more than 10% loss

Moderate Not more than 20% loss

Heavy Not more than 40% loss


Sup

erse

ded

by T

HR

CI 1

2008

ST

v2.0

, 25/

06/2

018



8.2. Material strength The material strength values shall be established in accordance with the requirements of

Section 8.2.1 and Section 8.2.2.

8.2.1. Steel, wrought and cast iron In the absence of test data or designated steel type (on drawings or in specifications) the values

listed in Table 2 and Table 3 shall be used in the capacity assessment.

Table 2 – Material properties and factors for plates and sections

Material Yield (MPa) Ultimate (MPa) Elongation (%) Capacity factor ɸ

Wrought iron 190 longitudinal 150 transverse

300 10 0.85

Steel pre 1910 210 400 20 0.90

1910 to 1940 230 400 20 0.90

1941 to 1970 240 400 20 0.90

After 1970 250 400 20 0.90

Table 3 – Material properties and factors for rivets

Material Yield (MPa) Ultimate (MPa) Elongation (%) Capacity factor ɸ

Wrought iron 190 longitudinal 150 transverse

300 10 0.80

Steel pre 1910 210 400 20 0.80

1910 to 1940 230 400 20 0.80

1941 to 1970 240 400 20 0.80

After 1970 250 400 20 0.80

Plastic properties shall not be used if elongation is less than 5%. The yield values shall be

reduced by 5% where sections greater than 20 mm thickness are used. Field or hand driven

rivets are assumed to be equivalent to shop rivets.

If testing to determine material tensile properties is undertaken, the requirements of AS 1391

Metallic Materials – Tensile testing at ambient temperature shall be met.

Additional requirements, detailed in Section 13.1 of this document, applies to wrought iron

materials.

For cast iron, material properties are highly variable. Testing shall be undertaken for critical

components to establish material properties.


Sup

erse

ded

by T

HR

CI 1

2008

ST

v2.0

, 25/

06/2

018



8.2.2. Reinforced concrete and pre-stressed concrete

For initial load rating, concrete strength shall be as designated on as-built drawings or from

previous destructive test data. In the absence of this information, the values listed in Table 4

shall be used in the capacity assessment.

Table 4 – Historical concrete strengths

Class of concrete

Alternative class designation (1)

Alternative class designation (2)

Specified 28 day compressive strength (PSI)

Specified 28 day compressive strength (MPa)

6K n/a n/a 6000 41

5.5K n/a n/a 5500 38

5K n/a n/a 5000 35

4.5K n/a n/a 4500 31

4K n/a n/a 4000 28

3.5K n/a n/a 3500 24

3K Class AA 1 : 31/2 3000 21

2.5K Class A 1 : 4 2500 17

2K Class B 1 : 5 2000 14

Where concrete testing is required, such testing shall be in accordance with AS 1012 Methods

of testing concrete. Concrete samples shall only be removed from those locations at an

underbridge where such removal has no impact on the overall strength or durability of the

underbridge concerned. All cores extracted shall be replaced with cementitious mortar with

characteristic 28 day strength not less than that of the parent concrete.

For reinforcement, the characteristic or yield strength shall be taken as specified in design

codes of the period for high yield and mild steel bars. In the absence of this information, the

values listed in Table 5 shall be used in the capacity assessment.

Table 5 – Historical reinforcing steel strength

Surface appearance of reinforcing steel

Year of construction Probable yield stress, ƒsy (MPa)

Probable yield stress, ƒsy (PSI)

Mesh 1914 to 1995 450 65000

Deformed mesh 1995 to now 500 n/a

Plain round, or any unidentifiable deformed bars or other steels (for example R or S bar)

Circa 1914 to 1995 230 33600

Twisted square bars 1957 to 1963 410 60000

Intermediate grade deformed

1960 to 1968 275 40000


Sup

erse

ded

by T

HR

CI 1

2008

ST

v2.0

, 25/

06/2

018



Surface appearance of reinforcing steel

Year of construction Probable yield stress, ƒsy (MPa)

Probable yield stress, ƒsy (PSI)

Hard grade deformed, grade 50

1960 to 1968 345 50000

Twisted deformed and CW.60

1962 to 1983 410 60000

Hot rolled deformed, grade 410Y

1983 to 1988 410 n/a

Hot rolled deformed, grade 400Y

1988 to 2000 400 n/a

Hot rolled deformed, grade 500N

2000 to now 500 n/a

For prestressed concrete, the requirements of AS 5100.7 Bridge design Part 7: Rating of

existing bridges shall apply.

9. Loads The loads for underbridges shall be in accordance with AS 5100 except as detailed in

Section 9.1 through to Section 9.4.

9.1. Live load The rating shall be derived from calculations based on the 300LA design loading as described

in AS 5100.

Ratings shall also be specified in terms of current trains operating on the network. The following

is a list of main line train consists on the TfNSW heavy rail network:

• Heavy Coal (HC) – based on 5/(90 Class) locomotives plus 120 tonne (NHRH) coal

wagons

• Main Line freight (MF) – based on 5/(82 Class) locomotives plus 100 tonne (NHRH) coal

wagons

• XPT/Explorer (XP)

• Suburban electric (SE)

• Waratah electric (WE)

• track laying machine (TLM) – leading crawler track loadings in operating mode

Appendix A contains a diagrammatic representation of the listed train consists.

For HC and MF load arrangements the locomotives shall be distributed along the train consist to

produce the worst load effects. For example, one or more of the locomotives is allowed to be

positioned between loaded wagons if that arrangement produces the worst load effect under

consideration.


Sup

erse

ded

by T

HR

CI 1

2008

ST

v2.0

, 25/

06/2

018



HC train consist loading shall only be considered for assessments carried out on those

underbridges on the Main North Line between Woodville Junction to Flemington South.

9.2. Nosing load Nosing load shall be in accordance with AS 5100.2 Design Loads. The AEO performing a

bridge assessment shall note that a nosing load application is required for all train consists

specified in Section 9.

9.3. Wind load A serviceability wind speed of 20 m/s shall be used in the load rating assessment of railway

underbridges. The AEO shall note that serviceability wind is included with Ultimate Limit State

load cases.

9.4. Earthquake load Each load rating performed shall include a rating arising from earthquake loads in accordance

with AS 5100.2.

For the purpose of earthquake load rating, all underbridges on the TfNSW heavy rail network

shall be classified as Type III in accordance with AS 5100.2. If the underbridge under

consideration fails based on a Type III classification, the underbridge shall be re-assessed as

Type II in accordance with AS 5100.2.

10. Load effects The load effects for underbridges shall be in accordance with AS 5100 except as detailed in

Section 10.1 and Section 10.2.

10.1. Load factors Load factors for dead loads and railway traffic (live load) shall be in accordance with Table 7.3

of AS 5100.7.

The load factor for the track laying machine shall be taken as 1.4.

Where the load rating factor of a component or connection is less than unity (1.0), the load

factor for live load (LL) shall be calculated based on load rating factor being equal to unity (1.0).

For example, if rating = 0.8 with LL load factor = 1.4, then LL load factor will be less than 1.4 for

load rating factor = 1.0.


Sup

erse

ded

by T

HR

CI 1

2008

ST

v2.0

, 25/

06/2

018



10.2. Dynamic load allowance The dynamic load allowance (DLA) for railway live load effects is a proportion of the static

railway live load calculated in accordance with AS 5100.2.

The minimum value of DLA shall not be less than 0.1.

The DLA for the track laying machine loading shall be taken as 0.1.

11. Wind and sway bracing The wind and sway bracing on existing steel structures shall be considered for wind load effects

in accordance with AS 5100.

Older generation wind and sway bracing on existing steel structures generally consists of

angles and flat bars. This bracing is generally found not to have adequate capacity for current

rail traffic with no evidence from the inspection that the bracing is overloaded. Where wind or

sway bracing under the combined action of wind and live loads govern the load rating, a rating

factor without the wind bracing governing shall also be provided.

12. Fatigue Fatigue is the cumulative effect upon a structure of a recurring load over time.

A fatigue assessment is an estimation of the cumulative damage in a bridge component under

repeated loading for the purpose of estimating the remaining fatigue life of the asset. The

remaining fatigue life of components shall be established as part of this assessment. The

remaining fatigue life shall be established on the assumption that current timetable load

arrangements are maintained into the future.

The fatigue assessment shall be performed in accordance with the requirements of AS 5100.7.

If an underbridge is shown to have reached the end of the nominal fatigue life as assessed in

accordance with AS 5100.7, an additional detailed analysis via strain-gauge measurement shall

be considered in consultation with the maintainer and operator. This analysis shall be in addition

to any risk management requirements which are stipulated by AS 5100 in this situation.

The means by which an AEO determines the load history and cumulative fatigue damage of an

underbridge shall be agreed with the maintainer and operator in advance of the commencement

of a fatigue analysis.

Fatigue analysis for rivetted underbridges shall be in accordance with EN 1993- Eurocode 3:

Design of steel structures.


Sup

erse

ded

by T

HR

CI 1

2008

ST

v2.0

, 25/

06/2

018



13. Reporting A written report based on the results of the load rating shall be prepared by the AEO. The report

shall comprise an executive summary, engineering details and appendices.

The report shall include an as-built general arrangement layout drawing of the bridge showing

the arrangement of the main bridge components and the span layout.

All relevant material strengths, section losses, material factors, DLAs, wind speed, fatigue

criteria and any assumptions shall be clearly tabulated.

Load rating results are to be tabulated for as new and as is conditions, and with and without full

DLA.

The type of vehicles and the effect of any speed restrictions that are in force, or that are

proposed, shall be shown.

Where the rating is less than unity (1.0), the following information shall also be included:

• the reduced speed required to increase the rating to unity (1.0), that is, the reduction to

DLA with respect to a reduced speed

• the calculated load factor for live load with full DLA

The results of the fatigue analysis shall also be provided.

Sample layouts for the presentation of the rating results are outlined in Appendix B and

Appendix C.

13.1. Wrought iron test results The reporting of test and load rating results for wrought iron structures shall include the

following:

• tensile properties

• Charpy values

• temperature for Charpy tests

• origin of sample (that is the name of the location)

• sample location size and orientation (for example, transverse)

• date of manufacture or best estimate

• extensometer charts for tensile tests

• specific train consist axle load configurations that are referenced and that are not included

in Appendix A or AS 5100 shall be shown diagrammatically


Sup

erse

ded

by T

HR

CI 1

2008

ST

v2.0

, 25/

06/2

018



Yield strength shall be determined using test results where testing is undertaken. The average

and the standard deviation shall be calculated and the yield strength shall be taken as the

average yield strength minus two times the standard deviation.

Ultimate strength shall be calculated similarly.

13.2. Wind and sway bracing The rating report shall specifically comment on the condition of the existing wind and sway

bracing. This report shall include inspection frequency, intervention levels and response times

necessary to maintain safety.

13.3. Executive summary The executive summary shall comprise a brief description of the railway underbridge, a table

that summarises the results of the load rating assessment (see Appendix B for a sample

layout), and a summary of conclusions and recommendations.

13.4. Engineering details The engineering details are typically a more in depth narrative of the load rating assessment

activity. The description of the railway underbridge is provided in greater detail. The

methodologies for the load rating assessment and fatigue assessment shall be clearly

described and included in a summary of live load cases used in the assessments. The results

shall be tabled in much greater detail (see Appendix C for an example of a layout).

13.5. Appendices The appendices shall include the following items:

• photographs of the underbridge (an elevation shot and a shot along tracks)

• bridge capacity

• load effect summary

• inspection summary

• theoretical fatigue damage

• an engineering drawing showing the as-built general arrangement of the underbridge


Sup

erse

ded

by T

HR

CI 1

2008

ST

v2.0

, 25/

06/2

018



Appendix A Loading diagrams Figure 2 contains a diagrammatic representation of the train consists listed in Section 9.1 of this document. TS TOC 1 Train Operating Conditions

(TOC) Manual – General Instructions contains information on rolling stock codes, which are shown in the parentheses (for example NHRH) in the

diagram. The overall vehicle length dimensions shown are measured to the vehicle coupler pulling faces in millimetres.


Figure 2 – Loading diagrams Sup

erse

ded

by T

HR

CI 1

2008

ST

v2.0

, 25/

06/2

018



Appendix B Bridge load rating executive summary table – sample layout The bridge load rating executive summary shown in Table 6 provides an example of criteria required for load rating assessment. The text in italics indicates

information the assessor would capture.

Table 6 – Sample bridge load rating executive summary table

Bridge and type: Central Road Underbridge

Location: Central

Route and tracks: Main Suburban: Up Main & Down Main

km: 1.000 km

Design drawing load capacity: M270

Critical bridge components for nominated rating vehicles

300LA(2) MF(2)

As new As is As new As is

Bridge member or connection or critical section (1)

Design action(1)

As is section loss (% and element)

Rating factor (RF)

Load rating (LR)

Rating factor (RF)

Load rating (LR)

Load rating without DLA (α=0.1)

Reduced speed for RF=1 (If applicable)

Rating factor (RF)

Load rating (LR)

Rating factor (RF)

Load rating (LR)

Load rating without DLA (α=0.1)

Reduced speed for RF=1 (If applicable)

Main girder Moment 10% bottom flange

1.25 375LA 1.20 360LA 439LA N/A 1.75 1.75MF 1.7 1.7MF 2.3MF N/A

Main girder Shear 20% web thickness

1.00 300LA 0.91 273LA(4) 305LA 41km/h 1.4 1.4MF 1.3 1.3MF(4) 1.6MF N/A

(1) The critical bridge structural member or connection or section with the critical design actions shall be included for each reference vehicle.

(2) Additional columns or tables can be added or deleted for the nominated rating vehicles and bridge specific items and actions.

(3) Additional rows can be added to note load rating subsequent to any bridge component proposed strengthening or repair.

(4) Critical load rating(s) shall be highlighted. In the example above load critical rating entries are in bold text © State of NSW through Transport for NSW Page 21 of 24 S

uper

sede

d by

T H

R C

I 120

08 S

T v2

.0, 2

5/06

/201

8



Appendix C Bridge load rating engineering assessment summary table – sample layout The bridge load rating engineering assessment shown in Table 7provides an example of criteria required for load rating assessment. The text in italics indicates information the assessor would capture.

Table 7 - Sample bridge load rating engineering assessment table

Assessment Type: Ultimate Limit State (ULS) as new and as is [or Serviceability Limit State (SLS) as new & as is etc.]

Bridge & Type: Central Road Underbridge

Location: Central

Route & Tracks Carried: Main Suburban: Up Main & Down Main

Km: 1.000 km

Design drawing load capacity: M270

Nominated Rating Vehicle (LRV): 300LA

Bridge component(1)

Critical design action(2)

Member length (L)

As is section loss (% & element)

Capacity reduction factor (Φ)

As new design capacity (ΦRu)

As is design capacity (ΦRu)

Dead load factor (γg)

Super imposed dead load factor (γgs)

Factored permanent load effects PE [γgSg*+ γgsSgs*+ Sp*+Ss*+St*]

As new Available capacity for live load effects [ΦRu-PE]

As is Available capacity for live load effects [ΦRu-PE]

Live load factor (γL)

Dynamic load allowance (α)

Multiple track factor (W)

Factored live load effects [γL(1+α)W(S*L)](3)

As new As is

Rating factor (RF)(3)

Load rating (LR)(3)

Rating factor (RF)(3)

Load rating (LR)(3)

Load rating without DLA (α=0.1)(3)

Reduced speed for RF=1 (If applicable)(3)

Main girder Moment 20m 10% bottom flange

0.9 3960kNm 3600kNm 1.1 1.4 600kNm 3360kNm 3000kNm 1.6 0.34 1.00 2500kNm 1.25 375LA 1.20 360LA 439LA

Main girder Shear 20m 20% web thickness 0.9 1360kN 1260kN 1.1 1.4 260kN 1100kN 1000kN 1.6 0.23 1.00 1100kN 1.00 300LA 0.91 273LA(4) 305LA 41km/h(4)

Longitudinal Stringer

Primary X girder

Primary X girder to Main Girder rivets

Primary X girder to Main girder cleats

End cross girder

Sway bracing

Wind bracing

Deck slab

Bearing

Trestle

Headstock

Pier

Pile cap

Abutment

Abutment foundation

Pier foundation

Piles

LOWEST RATING (4) 1.00 300LA 0.91 273LA(4) 305LA 41km/h (4)


Sup

erse

ded

by T

HR

CI 1

2008

ST

v2.0

, 25/

06/2

018



(1) All relevant structural members and connections and critical sections shall be

included (examples shown only).

(2) Actions shall include AS 5100.2 railway traffic relevant possibilities such as

moment, shear, torsion, axial, centrifugal, braking, traction, nosing, lateral, derailment,

wind and combinations.

(3) Additional columns or tables can be added for other nominated rating vehicles and

bridge specific items.

(4) The critical load rating(s) shall be highlighted. In the example in Table 7, critical

load rating entries are in bold text.


Sup

erse

ded

by T

HR

CI 1

2008

ST

v2.0

, 25/

06/2

018



Appendix D Suggested reading The following documents are included here as suggested reading. These documents may assist

with providing important background information on the assessment of underbridges and on the

TfNSW organisational context.

AS 1170 Structural design actions

AS 3600 Concrete structures

AS 13822 Basis for design of structures – Assessment of existing structures

AS 1816 Metallic materials

AS 5100.5 Bridge design Part 5: Concrete

AS 5100.6 Bridge design Part 6: Steel and composite construction concrete

ASTM E3 - 11 Standard guide for preparation of metallographic specimens

ASTM E384 Standard test method for Knoop and Vickers hardness of material

BS 7608 Guide to fatigue design and assessment of steel products

EN 1993-1-9: Design of steel structures – Part 1-9 Fatigue

ESC 100 Civil Technical Maintenance Plan

ESC 302 Structures Defect Limits

ISO 12696 Cathodic protection of steel in concrete

TMC 300 Structures General

TMC 301 Structures Examination

TMC 305 Structures Assessment

TS 10760 Guide to interpretation of organisational role and process references in RailCorp

standards

TS 10760 SMS Interpretation guide RailCorp SMS references within RailCorp engineering

standards

TS 10762 Legacy RailCorp Standards Interpretation


Sup

erse

ded

by T

HR

CI 1

2008

ST

v2.0

, 25/

06/2

018

Technical Note - TN 006: 2016 · Technical Note - TN 006: 2016 . Subject: Update to live load in T...

Documents

Transcript of Technical Note - TN 006: 2016 · Technical Note - TN 006: 2016 . Subject: Update to live load in T...