Steel Intensive Terminal Building 311007

7/15/2019 Steel Intensive Terminal Building 311007

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*Senior Manager (Civil & Structural)

Institute for Steel Development & Growth (INSDAG)Ispat Niketan52/1A Ballygunge Circular Road, Kolkata 700 019, Tel: (033) 2486 0855 / 58 / 59; 2461 4045 / 47; Fax: (033) 2461 4048 / 2486 1013E-mai: [email protected]; Web site: www.steel-insdag.org

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Steel Intensive Multi-storeyed Bus Terminal BuildingGoutam Chakraborty*

Introduction

The use of steel in Multi-Storeyed Buildings in various forms is a rare practice in India. In fact, very recently a surge in

upward trend of use of steel in building has been observed in India. Earlier, steel as a building material was used in

Industrial structures like Power Plant, Chemical / Petro-chemical Plants, Workshop Building etc. Institute for Steel

Development & Growth (INSDAG) is playing a pivotal role not only in enhancement of use of steel in Residential as well asCommercial Buildings, but also involved in setting examples by implementing some of the key projects recently being

executed in India. Interstate Bus Terminal (ISBT) complex at Sarai Kale Khan, New Delhi is one such project where a

blend of various sections with appropriate use has been tried.

Abroad, steel is used in abundance to give not only more strength and durability of the building system, but also it adds to

the aesthetics of the same, which enhances the owners pride. The Terminal building complex is essentially accommodating

the buses plying between states and local area and private vehicles including taxis and scooters. The building is having

four distinctly marked levels viz. Basement, Ground Floor, Mezzanine Floor and First Floor levels. Further, the basement

is stepped up to two levels, the half portion of the total plan area having a clear height of 5.0M to accommodate local buses

and the other half having a clear height of 3.0M to accommodate taxis, scooters and private vehicles. For easy

maneuvering of buses, the concept of long span structure has been introduced. The spans of primary beams have been kept

as 18.0M starting from basement level up to first floor level. The roof has been conceptualized as a folded plate roof

consisting of articulated plane trusses connected three dimensionally to generate the folded plate configuration.

Hence, it is desired from an architect / structural engineers point of view to use various steel sections in building

construction to propose stronger, more durable, open planning coupled with aesthetically elegant, and cost effective

solution of the structural system which is otherwise almost impossible to develop in conventional method of construction.

Key Words

Basement, Beams, Building, Bus, Columns, Covered area, Elegant, Folded Plate Roof, Foundation, Framing system,

Ground Floor, Inter-state, Mezzanine Floor, Piles, Pile cap, Primary Beams, Retaining Wall, Secondary Beams, Steel-

concrete Composite, Tension Piles, Terminal, Water proofing, Yield Strength

Structural Scheme for the Terminal Building

a) Basement and Foundation

The geometric shape of the building in plan resembles a part of an ellipse. The longitudinal distance (approximately 180.00

M in length) representing the part of major axis of the ellipse whereas the minor axis represents the maximum dimension of

width (80.00 M in length) of the building. Figure 1.0 shows the plan at Basement level. The total covered area per floor is

around 17,000 Sq. M. Out of which 9,000 Sq. M has been kept for parking of local buses and 8,000 Sq. M area for parking

of Taxis, Scooters and other Private Vehicles at basement level. The entire basement has been conceived as an underground

RCC structure which can withstand water pressure from bottom as well as vehicular loading. The basement floor slab

(panel dimension 18.0 M x 6.575 M) has been subdivided into 6.0 M x 6.575 M panels for optimum design of floor slab by

introducing Tension Piles to cater for uplift due to huge water pressure at foundation level. The basement is supported on

Pile cap and group of piles under each structural column spaced apart by 18.0 M. Intermittent pile caps were introduced for

transferring loads through Tension piles. Since the basement level is much below the Formed Ground Level, a retaining

wall has been conceived surrounding the building periphery. The peripheral wall of basement has been designed to

withstand outer soil pressure along with horizontal water pressure. The peripheral basement wall is situated away from the

peripheral column line so as to impart natural ventilation and lighting to the basement level. Tie beams have been provided

predominantly to tie the pile caps in both the directions. These beams are also acting monolithically with the basement floor

slab to take appropriate share of load. The entire basement slab has been treated for water proofing by suitable water-

proofing material and the locations of pile caps are pressure grouted to prevent ingress of water from underneath.


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The A type truss modules are tied longitudinally by tubular members and at periphery braced to cater for horizontal loads

coming on to the structure. Each such A type of truss modules are having average span of 36.00m along the width of the

building and the average base dimension of A module is 13.15m. The height of each A module is 4.50m. The gutter

line is matching the valley line at the junction where A modules are connected side by side. The gutters are spanning

along the width of the building at each valley location. At inclined articulated column location water will come out from the

gutters at steep slope baffled by intermittent baffles fitted over articulated columns and the runoff will be collected by a

common outer gutter at the periphery of the building at an elevation of +9.00m. The eaves level is varying from 6.5M at

longitudinal centre location to 5.5M at periphery of the building. To take care of lateral forces / horizontal wind forces, the

eaves level has been tied with separate horizontal bracing system.

The monitor roof has been considered as an elevated structural system having sides covered with coloured glasses to allow

sufficient natural lighting and louvers are provided to allow sufficient ventilation at roof level. The monitor trusses are

having varied spans gradually tapered from centre of the building. The monitor roof is tied with horizontal bracing system

at eaves level to provide stability against lateral forces.

Fig. 3: 3D Elevation showing detail of Folded Plate Roof and the Elevated Monitor Roof for Terminal Building

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RCC GUTTER

1 52 43

54321

LVL +1.55M

SPACEFRAME

INTUMESCENTCOATING ONHOLLOWROOF MEMBERS.

ALUMINIUMLOUVRES

FOUNDATIONAS/STR.

SSSPOUTSS SPOUT

MEZZANINE IN ELEVATION

FOUNDATIONAS/STR.

+4800 (210.3)

+1550 (207.05)

0 (205.5)

-2800 (202.7)

-4800 (200.7)

+9000 (214.50) +9000 (214.50)

+4800 (210.3)

+1550 (207.05)

0 (205.5)

-2800 (202.7)

-4800 (200.7)

HOARDINGS

CUT OUT

RCCRET. WALL

13

57

9

13

57

9

SPACEFRAME

Fig. 4: Sectional Elevation showing detail of Folded Plate Roof for Terminal Building

Scope of Work for Structural Consultant

As structural consultant, the scope of work or battery limit for INSDAG is as follows:

Analysis, design and detail engineering of all pertinent structures for both temporary ISBT and permanent ISBT


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To give concurrence for selection of type of foundation optimally, recommendations regarding bearing capacity of

soil, viability of soil investigation report etc.

To submit design calculations, computer output or any other special technical literature to substantiate design

calculation pertaining to all relevant structures

To submit relevant design drawings

To submit bill of quantities for all civil & structural items based on design drawings

To guide the fabricator for preparation of fabrication drawings in all respect

Review and checking of all fabrication drawings

Design Considerations for Terminal Building

For the Analysis and Design of the building, the following design parameters have been considered:

Soil data as per the geotechnical investigation report of the proposed site as furnished by Soil Consultant / PWD.

The columns are considered fixed at the top of the foundations.

The connections between columns and primary beams are rigid i.e. moment bearing connections.

RCC work shall be made of suitable Grade of concrete as per stipulations of relevant standards.

High tensile steel sections of grade Fe 540B conforming to IS: 8500 (latest edition) will be considered for major /

load bearing structural elements, and for non-load bearing or other structural elements, combinations of both high

tensile and mild steel sections will be considered for analysis and design.

Steel sections encased with RCC are considered for composite columns.

Nelsons shear studs having yield strength of 385 MPa are considered to ensure anchorage between RCC slab and

steel beam.

The folded plate steel roof shall be made of MS pipes conforming to IS: 1161 covered with a conglomerate of a

composite material made from two steel profiled sheets of suitable grade separated by a layer of glass / rock wool.

For underground peripheral retaining wall structures, horizontal and vertical PVC water stop bars of required

width shall be provided to ensure proper water proofing of retaining wall. Alternatively, pressure grouting along

with admixtures of water proofing compound may be adopted.

To ascertain proper water proofing of folded plate steel roof, suitable water proofing treatment shall be provided at

the locations of lapping of sheets, joints formed with screws, bolts etc.

The following loads are considered for analysis and design:

Surcharge Load over ground around the building 20.0 KN/m2

Superimposed load on floor / roof:

Finish load 1.25 KN/m2

Imposed Load As per relevant clauses of IS-875 (Part 2) and IRC 6

Self-weight and dead load As per actual calculation

Wall load with bricks 12.0 KN/m

(200 m thick external wall for shops)

Wall load with hollow bricks 7.5 KN/m

(125 m thick internal partition wall)

Water distribution system & loading of overhead reservoir:


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Overhead Reservoir (self-weight + water) As per requirement

For stair block / cat ladder as per architectural requirements:

Finish load As applicable

Live load 3.0 KN/m2

Height of typical floor as per architectural drawings

Wind load as per IS 875 1987 (Part 3) for : Basic Wind Speed 47 metres/second

K1 factor 1.07

K2 factor varying with height 1.05

(As per Terrain Category II)

K3 factor 1.0

Earthquake load as per IS 1893 2002 for Zone IV.

For various load combinations, the combinations shown in Chapter C1 will be considered. However, if required,

any other load combinations may also be considered for the purpose of analysis and / or design check.

Fire Protection of Bare Steel Members for Terminal Building

All the bare steel elements of the building will be protected with the application of vermiculite plaster of suitable

thickness (depending upon requirement of fire rating in hours, in this case the fire rating is 2 hours for both the

roof structures and columns as per IS: 1641, 1642 and 1643). However, intumescent paint has been used for the

roof trusses and vermiculite has been used for columns. Vermiculite is a naturally occurring siliceous volcanic

rock compound and when exfoliated by heat process, it forms flakes containing microscopic air layers which give

optimum insulation properties and makes it a non conductor of electricity and an insulator for both radiant and

conducted heat. Vermiculite plaster when used with special additives and ferro-cement adds to the properties of

perlite i.e. fire resistant and stoppage of transfer of high temperatures through it into RCC, thus reducing thechances of deformation of structural steel incase of an accidental fire. Further, this will help in reduction of spread

of fire and reduction in large scale expenses due to replacement of structural elements after fire. Combined with

fire resistant paints the application of vermiculite plaster is a must incase of high rise buildings, important

buildings, go-downs of inflammable products etc. The portion of roof structures which are above 6.75M from El.

+ 9.00M are painted with intumescent paints to provide fire resistance to roof members.

Connection and Construction Philosophy for Terminal Building

The structural system of the building is conceived as portal frames in both the orthogonal directions having major

connections as bolted using HSFG and / or welded suiting to site conditions. The primary beams and columns are

connected through predominantly moment bearing connections whereas the secondary beams not being a part of

the framing actions are connected to column/beams with predominantly shear connections. The steel sections shall

be fabricated at shop and assembled and erected at site with proper splicing etc. depending on the available length

of the member and considering minimum wastage of material. The members will be joined together by splice

plates / suitable structural sections with the help of permanent bolts and the plates shall be bolted / welded to the

main members after securing proper erection. All the splices shall be designed for full member strength of the


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maximum area of section being joined at the connection. Gusset plates, angle cleats etc. shall have minimum

thickness of 8 mm and proper connection methodology (either using HSFG bolts or Welding) shall be adopted at

site for connecting different members with different type of material (either similar or dissimilar type i.e. Mild

Steel to Mild Steel, High Tensile to High Tensile or Mild Steel to High Tensile steel).

All M.S. holding down bolts for base plates shall be designed satisfying the requirement of proper anchorage with

RCC pedestal / foundation system and shall have sufficient reserve strength to cater for the actual design stressresultant imparted on them.

Steel Intensive Terminal Building 311007

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