The “National Museum of Indian Cinemas” is located in South Mumbai – in the congested, prime and sensitive area of Pedder Road, in Mumbai. The structure comprises of lower ground floor + Ground Floor + 4 Upper Floors with mezzanine floor between 3rd and 4th floor and 4th and 5th floor + Terrace Floor.The “National Museum of Indian Cinemas” is located in South Mumbai – in the congested, prime and sensitive area of Pedder Road, in Mumbai. The structure comprises of lower ground floor + Ground Floor + 4 Upper Floors with mezzanine floor between 3rd and 4th floor and 4th and 5th floor + Terrace Floor.
Mahimtura Consultants was appointed as a principal structural design consultant on the said Project. The scope of works includes carrying out structural analysis, concept and final design, issue of construction drawings, site supervision as and when required and issuing structural stability certificate. Structural Aspect Structurally, the entire building is designed as composite steel building, as per European Code EC4 and American Code AISC 360 – 10. The composite design is opted in view of the cramped location of the project and various site constraints, architectural restrictions.
The structure is designed for combination of gravity and lateral load, as per seismic and wind load conditions, in accordance to the codal provisions. Columns are also designed as a composite element in order to achieve minimum sizing, thereby resulting in optimization. A suitable and most appropriate structural system is evolved using combined benefits of both, the concrete and steel. The structural system has been configured to overcome 1st mode torsion caused due to the shape of the building.
Span of beams varies from 8 m to 15 m and floor to height is 3.0 m to 3.8 m. By providing beams with longer spans, created column free large spaces for various areas viz:a) Auditoriums (Approx. 15 m x 22 m) b) Escalator cut outs (Approx. 5.5 m x 13 m)c) Exhibition halls (Approx. 15 m x 22 m)d) Food court (Approx 15 m x 22 m)
A steel building with composite design shall offer an increased carpet to build up Area ratio which is beneficial to the end user. As experienced members of India’s construction industry, it our moral responsibility to encourage the building of steel structures as they are the need of tomorrow. Though the cost of construction per sq. ft. is slightly high with steel, it gets offset by the shorter project duration, better clear floor headroom and more flexibility for the end user.
Use of 355 grade steel helped in optimizing the design resulting in sleeker column look and reduced column sizes offering an increased carpet area and headroom for the client. Selection of 355 grade sections was undertaken on the basis of sections readily available in the market, from material procurement perspective.
In order to create an additional stiffness in the structure, we have ……a) RCC shear walls on all floors.b) Very strong composite columns (Structural Steel and Concrete) c) High grade concrete (M 40), High grade reinforcement steel (Fe 500) and High grade structural steel (355 Mpa).
Additional wind bracings are proposed at some selective locations. Self-supporting decking sheets are used for floor slabs as per required fire rating. Exposed steel beams are protected against fire, by providing spray vermiculite coating / treatment of 2 hours fire rating.
The versatility of steel allows infinite solutions and gives architectural freedom to the designers to create iconic landmarks for human beings to used. The use of 355 grade steel helped in optimizing the design and resulted in sleeker column section. The reduced column sizes offer increased carpet area and headroom for the Client. We could use 355 MPa and 420 Mpa, high grade steel sections for all future steel buildings, if they were made easily available in multiple sections and at reduced cost. The speed of construction of the sleeker section would definitely help the steel construction industry to grow.
Hiten Mahimtura & Sailesh Mahimtura
Directors, Mahimtura Consultants Pvt. Ltd
The contractor prepared the Quality Assurance Plan, which was reviewed by the Inspection Agency and approved by the Client and MCPL. The Client appointed an independent agency to conduct all necessary tests as per approved Quality Assurance Plan (QAP) and/or Inspection and Testing Plan (ITP) which shall typically included material identification and testing, setup inspection, weld visual inspection with relevant NDT method like radiographic (RT), ultra-sonic (UT), Magnetic particle (MT), Penetrant Test (PT) and if required for other non-destructive tests on the structural steel during various states of work starting from material procurement, material testing, weld test, qualifying the welding procedure and welders, checking fabrication and erection work and checking of fire proofing works etc.
Structural UniquenessWith large span of beams and restricted floor to floor height, beams are designed as composite beams, having shallower depths. Main elevation Glass facade of size 30 m x 40 m is supported on pre-stressed cable net. Cable net is formed by diagonally placed cables in two perpendicular directions as per elevation requirements. Cables are pre-stressed to support glass façade. Building columns are designed for pre-stress forces applied to cables.
Challenges Due to inadequate handling space at site, procurement, fabrication and testing of the structural steel was done in the contractor’s fabrication yard. The prefabricated members were then transported to site, lifted and finally erected. The steel connections are kept simple, using High Strength Friction Bolts Grip (HSFG) bolts.
Design of cable net is carried out in such a way that horizontal deflection of entire Glass façade under wind forces is well within permissible limits as per code requirements. It was a real challenge to satisfy structural requirements within architectural restrictions like spacing of columns up to 15 m and floor to floor heights are 3.0m to 3.8m.