Adani Group is coming up with its corporate office in Shantigram Ahmedabad. The entire project was sub-divided in North Wing, West Wing, South Wing and Auditorium. The entire development had two basements to cater for the parking requirements and to house the services. North and south wing consists of ground floor, 4 office floors to house various group companies, cafeteria is planned at the roof of north & south wing. West wing houses a stilt parking for executives, a triple height executive atrium, data centre floor, 7 office floors and Director’s floor at the top. On the East side, Auditorium is planned with executive dining on the roof of the Auditorium. Dedicated separate elevators and entrance are planned for the chairman.
Highpoint of the Structure
The major highlight of the structure is the Auditorium. As per the original design, the auditorium was planned as cantilevered structure supported on inclined shear walls on the fixed end. The approximate size of auditorium is around 32 m x 30 m, cantilevered trusses 10 m deep were proposed on the two edges anchored to the shear wall. Steel plate girders were planned to support the floor deck of the auditorium floor and supporting the floating columns to support the roof of the auditorium.
Subsequently, pair of tree columns were introduced to facilitate the speed of construction and to economise the structure. Main public drop-off for the office is below the auditorium. Auditorium structural system comprises of plate girders at the floor level and trusses at the roof level to support the executive dining area. Due to large spans structural steel became an obvious choice for the structural system.
Plate girders spanning from core to the arms of the tree columns formed the primary supporting system. Secondary beams spanned between girders to support the auditorium floor and raking slab. Trusses were fabricated using B/up box sections. The depth of the truss is approximately 4.5 m plate girders spanned between the trusses. Secondary beams spanning between plate girders were provided to support the deck slab construction.
The other interesting aspects of the structure are the four-floor high Public atrium spanning 30 m, and triple height Executive atrium spanning 16m which supports a heavily loaded Data centre above it. In the public atrium area, architects wanted large column free span. However, some utilities had to be housed over the atrium at fourth floor. To support the large column free are deep girders spanning 30m were proposed and the fourth floor was suspended from these girders. For the executive atrium area, between to support heavy loads because data centre and large spans steel construction was proposed.
The major highlight of the structure is the Auditorium. As per the original design, it was planned as cantilevered structure supported on inclined shear walls on the fixed end. The approximate size of auditorium is around 32 m x 30 m. Cantilevered trusses 10 m deep were proposed on the two edges anchored to the shear wall. Steel plate girders were planned to support the floor deck of the Auditorium floor and also supporting the floating columns to support the roof of Auditorium. Subsequently, pair of tree columns were introduced to facilitate the speed of construction and to economise the structure. Main public drop-off for the office is below the Auditorium. Its structural system comprises of plate girders at the floor level and trusses at the roof level to support the executive dining area. Due to large spans, structural steel became an obvious choice for the structural system.
– Manish Negandi, Sr GM, Sterling Engineering Consultancy Services Pvt. Ltd.
Flooring System
The flooring system for the basements was flat slab system with drop panels. In the extended podium area, at ground floor, conventional beam slab system was proposed to take care of landscape loading and for fire tender movement. For the office wings (north and south) conventional flat slab with drop panels are proposed to maximise the clear height of structure. The roof of north and south wing supports cafeteria structure on the fifth floor. The roof of the cafeteria is supported on space structures and supported on four tree columns.
West Wing being the tallest, it has been separated by expansion joint along the perimeter where it meets north and south wing. In the west wing, large column free spans were required because triple height executive atrium from first floor to fourth floor. Data centre for the group was proposed to be housed at the 4th floor. To support large spans, heavy loads and expedite the speed for of construction, steel beams along with deck slab construction was proposed. This enabled site team to ensure that construction of the floor was completed without resorting to triple height staging and avoid substantial back propping requirements. The flooring system for the office floors in the west wing is post-tensioned flat slab with drop panels. This was the most economical solution for large spans. Top floor houses the chairman’s floor.
Comparative Analysis
In order to optimize the material consumption, sample analysis and design exercises shall be undertaken with different combinations of member sizes for which the required reinforcement and formwork will be estimated. Results of these exercises were considered in arriving at the structural scheme of the building. Based on the studies, it was decided to adopt conventional RC flat slab with drop panels for the north and south wings. For the West Wing Post Tensioned Flat Slab with Drop Panels was finalised.
Grand Atrium
Architects desired for a grand atrium in the public area. This atrium was four floors high and was spanning 30 m. Various alternatives were discussed and debated; conventionally a large depth girder at fourth floor spanning 30 m would have been provided. SEC suggested to have girders at the Fifth floor and suspend the fourth-floor slab in order to have a sleek floor in the roof of the atrium and to utilize the higher headroom at the fifth floor. This also helped in avoiding the loss of areas at the fourth floor on account of the huge depth of girders. It was finally decided to proceed with option 1 for the Public atrium area to expedite the speed of construction and avoid multi-level staging and heavy back propping requirements.
Cost Optimization
SEC proposed to introduce tree columns at the edge of the auditorium to reduce the cost of construction for this area and also to have a simple methodology for erection. This resulted in change in anatomy from cantilever truss to simply supported truss thus reducing the tonnage of structural steel. It also eliminated the need of huge shear walls required in the earlier scheme to transfer the load safely on the main building and to ensure that the serviciability criterias are well within the permissible limits. The extent of savings is as depicted below:
In the west wing, data centre was placed above the triple height executive atrium. Initial scheme proposed for this area was post tensioned flat slab along with drop panels. During the execution stage, the locations of columns were modified to have large central span for the atrium. This resulted in revising the scheme to steel beam deck sheet construction. The time required for the construction using Steel beams was reduced considerably and requirement of back-propping of the slab till the basement level was completely eleiminated. SEC presented the incremental cost analysis for the clients to enable them to arrive at the decision.
On-time
This project was planned to start within short time span from the concept design. Hence, the schematic stage and tendering stage was completed within two months since conception. Additional efforts were taken by the design team keeping in mind the fast track construction schedule..The work on site commenced within six months from the conception. Continuous co-ordination with the design team and site team ensured smooth execution.Continuous co-ordination with fabricators ensured that minimum time was lost and the fabrication commenced parallely.
