Effects of Wind on A 3 Dimensional Steel Structure for the Central Corridor Roof (Central Spine) at TCS Campus at Siruseri, Chennai (India) - A Case Study

T. S. Gururaj, Technical Advisor, Bangalore, India. Ex. President, Potential Service Consultants Pvt. Ltd., Bangalore,. Nagaraja M. Thontalapura, Director – Technical, Innotech Engineering Consult Pvt. Ltd. Bangalore. Ex. Vice President (Civil/Structural), CPG Consultants India Pvt. Ltd., Bangalore,

With the advent of high speed computers, 3D structural modeling and analysis have evolved to new heights. Equally exceptional user-friendly finite element software tools have made the modeling exercise a lot easier than ever before. This paper will provide a case study on the evolution of the structural system for one of the modern architectural marvels of India. The authors, who were deeply involved in the various stages from concept to construction, will discuss in particular, the analysis and design of the central spine which resembles a “Giant Wasp” (as called by the concept architect). This paper will also discuss the structural system suitably provided for the huge cantilevers at the ends representing the tail, huge cantilevers at the sides representing wings, tall curved portals representing the legs and the pyramid shaped lattice girders representing the body of so called giant wasp. Also discussed in this paper, will be the behavior of the central spine structure due to wind.


The proposed techno park at Siruseri, Chennai, India is spread over a plot area of approximately 70 acres. It has 6 engineering blocks, customer care center, General services block, Training and library block and other facilities as in Figure 1.

TCS campus
Figure 1: TCS campus showing central spine

This paper will discuss about the central corridor roof between the engineering blocks which is also known as the central spine. The central spine serves as the shelter for people movement. This also houses the landscape which consists of water body and other facilities. This is spread over a length of 400 m. The architectural concept is such that 2 giant wasps each of 8 pairs of legs and long tails are facing each other. The formation of the entire structure is by means of 3 dimensional curves. In both the side elevations, it is symmetrical about vertical axis (refer Figure 2). In top plan, it is symmetrical about both vertical and horizontal axes as in figure 2.

Views of central spine
Figure 2: Views of central spine

Project team

Architect: Carlos Ott architects (Uruguay, South America); Resident architect: CRN architects (Chennai, India); Engineering Services: Potential Service Consultants (Bangalore, India); Review and Project Management Consultants: TCE Consulting Engineers (Bangalore, India)

Structural System

Main portals and arch bracings

Main portals are formed by intersecting gothic arches as shown in Figure 3. They are the main supporting elements of the central spine in the vertical direction. They are made of two outer pipes and one inner pipe as shown in Figure 3. These 3 pipes are connected by triangulated web members. They are further connected to the arch bracing members which are provided along the elevation. The outer and inner pipes form cantilever trusses called wings to support the purlins on them.

Main portals with arch bracing
Figure 3: Main portals with arch bracing

Middle wings
Figure 4: Middle wings

Middle wings

To reduce the span of purlins a truss system known as middle wings (Figure 4.) which are quite similar to the top part of main portals, are introduced in between the 2 portals. By this, the span of purlins is reduced to around 11 m which is reasonable. The middle wings are supported by the lattice and box girders running between the 2 main portals.

Lattice girder
Figure 5: Lattice girder

Lattice girder and Tail

Tail of central spine
Figure 6: Tail of central spine
The lattice girder as shown in Figure 5 connects the main portals in the longitudinal direction. Between 2 consecutive main portals, at the centre it supports the middle wing. The lattice girder is connected at the bottom exactly at the centre to the arch bracing in each span. It is extended from the base of top wing to the bottom wing forming a curved pyramid. Tail is the continuation of lattice girder at both ends converging at a point. Space frame method is used to form this structure as in figure 6. It is an open structure without any roof covering making it very obvious so that it looks like the tail of the “Giant Wasp.” The cantilever is about 35 m from the last portal. It is tied back to the 2nd portal to control the deflection in the vertical direction and horizontal “X” bracings are provided at the bottom to control deflection due to wind.


The two legs of each portal consisting of five pipes (including the arch bracing) are connected to a base plate with required stiffeners. Base plate is further connected to the podium column capital by means of cast-in holding down bolts.

Analysis and Design Data


Dead load

Wind load parameters
Dead loads and imposed loads have included the weight of all structural and architectural components on the basis of the unit weights as mentioned in the Table 1. Wind loads are based on the code provisions mentioned in IS 875 [1]. The wind speed is calculated using the parameters in Table 2.

Temperature loads and expansion joints

Elongation due to differential temperature is of high importance in long steel buildings. It can be taken care of by either providing expansion joints at an appropriate spacing or designing structural members for the additional moments caused by the temperature. Expansion gap between two structures shall be sufficient to accommodate temperature and shrinkage for effects due to wind. Expansion joints are provided at 2 locations along the length, breaking the whole structure into 3 parts known as Central part (1. no.) and Tail part (2. no.). Central part will have 7 spans. The final configuration of the whole structure is as shown in the Figure 7.

Central spine
Figure 7: Central spine divided into central and tail part with expansion joint

Materials used

Structural steel confirming to IS: 2062 with minimum yield strength of 310 N/sq.mm is used for all structural members. For expansion joints approved Teflon sheet is provided.

Wind Pressure Computations


Figure 8 shows the configuration of the central spine (CS) structure. There are sixteen bays of geometrically similar configuration of diminishing size from centre to ends. Each bay is around 21 m long. At the middle, the width is 35 m and height is 55 m, at the ends the width is 12 m and 18 m height.

Central spine
Figure 8: Configuration of central spine influencing wind pressure

The bays are open in the bottom, for example up to a height of 24 m at the centre, above which CS supports six wings symmetrically by the framework, which also supports Louvers (water barrier made of overlapping plates) at the roots of the wings with a porosity of 20%. The Louvers extend below F&L.

Types of wind loads

The following cases have been considered to analyze the structure:

Case 1: Wind from empty position of A to B

Case 2: Wind from the direction of B to A, with A absent.

Wind loads with CS and building B only, wind from position A to B

wind pressure coefficients
Figure 9: Overall wind pressure coefficients on portals
As shown in sketch 2 of Figure 8, the part of the wind below the point C will move on to B, gets diverted upwards and impacts to rear wing L. But wings K&L are partially shielded by F, G, H and their loads will be less than those values on G&H. Somewhat similar phenom- enon occurs on the bottom of F, where the Louvers below F block the flow partially, creating a positive pressure. The Louvers between F & G and G&H also create positive pressure (or makes negative pressure, less so). The nearest configuration in the Indian wind code IS 875-1987 is Table 8 [1] for the wings F, G and H, J, K and L all with φ=1. By considering shielding effect and the pressure build ups, the overall pressure coefficients with directions for all the wings and the Louvers are as in Figure 9. The configurations of Table 13 [1] and Table 14 [1] can be used as guidance with θ=00. These are used for the analysis of the entire structure. The local pressure coefficients listed in table 3 are used for designing the purlins.

Wind loads with CS and building B only, wind from position B to A

Local Pressure Coefficient
Here, the bottom of wing L is above the building B & hence the flow will be similar to that as wing F with wind from A to B. Loads on K & J will be similar to those on G & H of the earlier case. However since F, G and H are fully shielded by L, K and J their loads will be half of the previous values including those on Louvers.

Structural Analysis and Design

The structural analysis is carried out by creating a 3 dimensional space frame model using the commercially available software STRAP VER.11.5 for the load combinations as per IS 800 standards. Line elements are used in the finite element model with rigid nodes. Triangular surfaces were created to idealize the curved surface and pressure loads were applied perpendicular to the surface in the required direction. This method has helped in reducing the time that would have been spent for member load computation and its application on each member. In total, including both central and tail part, the structural model contains about 10,400 nodes, 36,700 members and 61,600 degrees of freedom.

Design of structural steel members is done using elastic method as per IS: 800 [2] with relevant allowable stresses. Each member is designed for combined stresses due to axial force, shear force and moments. Sample output for the analysis and design are shown in Table 4.

TCS campus


It is observed that the load combinations involving the wind loads computed using the pressure coefficients shown in figure 9 govern the design of members of the central spine structure. Since the structure is very light, the earthquake forces do not have any influence on the design. For academic purpose, the load combinations including earthquake, wind loads on members, live and dead loads are studied. The deflected shapes of the main portals with some governing load combinations are shown in Figures 10 and 11.

Deflected shapes
Figure 10: Deflected shapes for DL, LL and WL

Deflected shapes
Figure 11: Deflected shapes due to DL and WL

The pipe sizes used for the main portals are 350 mm diameter with thicknesses varying from 22 mm to 16 mm. For the other elements almost all available pipe sizes are used considering the most economical sizes and durability. The joints are connected by full strength butt welds. The thickness of base plate worked out to be between 70 to 80 mm for various portals by suitably providing the stiffener plates. Overall structural steel consumption is around 3000 Tons with a roof sheeting area of around 25,000 square meters. The central spine structure under construction is shown in Figure 12. Completed structure is shown in Figures 13 and 14.

Central Spine under construction
Figure 12: Central Spine under construction

Central Spine
Figure 13: Central Spine at background of Engineering buildings

Central Spine
Figure 14: Central Spine Completed


The authors would like to thank structural engineers Mr. B. N. Sridhara, Mr. Sajeev Thomas and Prof. G. N. V. Rao, Department of Aerospace engineering, Indian Institute of Science, Bangalore for their support and cooperation during the design stage. Authors are also thankful to the project team and clients Tata Consultancy Services Ltd for their cooperation in preparing this paper.


  • IS: 875 (Part 1, 2 and 3) – 1987, Indian Standard- code of practice for design loads (other than Earthquake) for buildings and structures, Bureau of Indian Standards, New Delhi, 1989
  • IS: 800 – 1984, Indian Standard- code of practice for steel design, Bureau of Indian Standards, New Delhi, 2002


The paper has been reproduced from the proceedings of SDSS 2010 (Stability and Ductility of Steel Structures 2010) with the kind permission from the organizers.

NBMCW December 2010

Click Here
To Know More / Contact The Manufacturer
Please fill in your details, we will contact you as soon as possible
Choose Title from the listPlease let us know your name.
Please let us know your Designation.
Invalid Input
Please let us know your email address.
Please let us know your City.
Please let us know your Contact Number.
Please brief your query.
Our other value-added services:

To receive updates through e-mail on Products, New Technologies & Equipment, please select the Product Category(s) you are interested in and click 'Submit'. This will help you save time plus you will get the best price quotations from many manufacturers, which you can then evaluate and negotiate.

Equipment & Machinery
Invalid Input
Building Products
Invalid Input

Exposed Reckli Finish Retaining Wall

The Reckli Finish Exposed Retaining Wall at Sabarmati Riverfront in Ahmedabad, using a 9m high Exposed Retaining Wall with a textured finish, and outer face using Formliner Formwork (known as Reckli), has grabbed the eyes of the world. Besides Read More ...

Delhi Metro Terminal 1 IGI Airport Terminal

One of the great benefits of Delhi Metro Phase 3 is that the domestic terminals of the Indira Gandhi Intl’ Airport have got Metro connectivity - a boon to the city’s domestic air passengers. While the Airport Express Link provides Read More ...

Simulating oversize and heavy vehicle manoeuvres using AutoTURN® from Transoft Solutions

Narrow mountain roads, steep hills and challenging ‘S’ curves are just part of the landscape in the ‘toe’ of Southern Italy, where wind farms are becoming a common part of the countryside. With green technology like wind Read More ...

Atlas Copco XA316 and XAT266 portable air compressors for Mumbai underground metro line

Atlas Copco portable air compressors have been deployed for the first underground metro line in Mumbai, and they are not just under the supervision of Mumbai Metro Rail Corporation Limited (MMRCL) but also under Read More ...

Indira Paryavaran Bhawan - First On-site Zero Net Energy Building of India

A zero-energy or a net zero building is a building with zero net energy consumption from outside source, which means that the total amount of energy used by the building on an annual basis is almost equal to Read More ...

Making of a Green Data Centre

Data centres make up 3% of global energy consumption. The main reason behind data centres being major energy guzzlers is the IT processing power, which has increased substantially to meet the growing Read More ...

Apollo ValueTec Plant Gives Competitive Edge to Rana Builders

Dhaka-based Rana Builders (Pvt.) Ltd. specialises in construction of roads, bridges and buildings. When purchasing a new asphalt-mixing plant, it wanted a product that would help meet its objective of on-time delivery Read More ...

BHAI concrete batch mix plant working at Asia’s largest waste-water treatment plant

Delhi Jal Board is setting up a 318 MLD (70 MGD) wastewater treatment plant at GT Karnal Road on the outskirts of Delhi. The ₹414.78 crore project, said to be the largest in Asia, is being constructed by EPC contractor-Larsen & Toubro Read More ...

The Fast Lane to Growth

When the National Highways Authority of India (NHAI) last widened the Vijayawada-Chilakaluripet Highway in the early 2000s, the country was at the beginning of its exponential economic growth. Since then, the nation’s GDP Read More ...

Insitu Investigation of Cinder Mound For Building Construction - A Case Study

Cinder is a waste generated as coal residues from the blast furnace of thermal power plant. It was accumulated over a long periods near railway station, Jamshedpur, Jharkhand, India. This dumping Read More ...

SoilTech Mk. III - 3rd Generation nano-polymer stabilization

Golfshire is a super-premium residential project in Bangalore, comprising luxury villas, a 18-hole PGA standard golf course, a large convention centre with seating capacity of 5000, and a 5-star hotel. The project is Read More ...

Especially Designed Rope Suspended Platform for Dam & Silo Projects

New Age Construction Equipment Engineering Company is one of the leading manufacturers of construction equipment like Rope Suspended Working Platforms (Gondolas/ Cradles), Bar Bending Machines Read More ...

New Age Offers Customized Solutions with Higher Productivity & Safety

As a leading manufacturer of construction equipment, we believe in superior performance, higher productivity & safety, faster execution and timely completion of projects,” says Mr. Jayesh Vadukiya Read More ...

Rehabilitation of National Highway at Tripura-Assam

The National Highway NH-44 is a major road artery for the North-East. The stretch of this highway leading to the border of Assam and Tripura (two states in the north-east of India), is the only land-link between Read More ...

Wirtgen Milling & Recycling Machines give Excellent result at NH-2

Wirtgen most compact and versatile machines W2000 and WR240 have been used for milling and cold in situ recycling works by contractor Soma during the road rehabiliation of Varansi-Aurangabad section Read More ...

KYB-Conmat's Advanced Mechanization Parallel Lower Ganga Canal Lining Project

Tougher norms for quality & safety in the industry have pushed contractors & developers towards advanced mechanization for their projects to deliver quality results in set timelines. It has also Read More ...

New Building Material & Construction World

New Building Material & Construction World
MGS Architecture

Modern Green Structures & Architecture

Modern Green Structures & Architecture

Lifting & Specialized Transport

Lifting & Specialized Transport

Indian Infrastructure & Tenders Week

Indian Infrastructure & Tenders Week