‘Time is Money’ is a very old saying, but, for Mumbai it is now a necessity, compulsion and reality.
Any RCC framed structure – small, medium or large – needs a specific time cycle, however efficient be the construction management on site. Therefore, when an option of alternative methodology and materials are now accessible and affordable, then why not steel? Structural steel has tremendous potential for flexibility in planning as well as expressing ‘structural aesthetics’.
The project – SMRITI 57 – is located in Juhu scheme in western suburbs of Mumbai on a small plot of 470 sq. mtrs. amidst a fully developed neighborhood. Thus, the challenge was to quickly execute the basic shell having extremely scarce marginal open spaces with least disturbance to neighbors.
The basic structural components of six floors of 10 mtr x 16 mtr spans of beams, columns and slabs consists of just four columns of 450 dia made out of 19 mm MS plates welded helically, braced with 600 mm deep ‘I’ beams fabricated from MS plates and readily available galvanized deck slabs by JSW duly stud welded. The entire structure may be imagined as a ‘chest’ with four legs and six shelves. After basic conceptualization of the structure, individual floor plans are drawn up as per end users requirements, which not only gave flexibility in planning, but, spellbound spatial feel. The complexity of internal walls and partitions, configuration of windows and voids, need for safe and secured spaces, private and open areas, and so on are all set within an orderly structural grid.
The erection of 450 dia columns above pile caps are 12 metre in length (which is the length of a trailer truck) and ‘I’ beams placed at a specific grid are fabricated by PLC at their factory in Daman and transported through trailer trucks. The entire erection process of over 900 sq. mtrs. in six levels executed within 14 weeks. It is worth a mention about the hydra and crane operators that they are exceptionally skilled in maneuvering their machines in extremely congested spaces with many impediments including trees and narrow accesses.
All the steel structural components are welded and finished with high quality epoxy primers and PU paints. They are intentionally kept exposed and blended with plastered masonry, aluminum windows, steel railings perched within the lush green foliage of peltophorum trees. Even many elements of interiors such as staircases, beds and tables, storage units, pipe shafts, etc. are made out of steel which further accentuates the use of steel in the project. There is always a concern for junctions in such type of composite structures such as between ‘I’ beam and masonry where ‘I’ beams are overlapped with concrete coping which totally overlaps the web of these beams.
For the requirement of internal stairs or double height ceilings, cutouts are simply created by not fixing deck slabs. Also the lateral beam at 3rd floor level is pushed back to create absolute double height for the terrace in plan as well as in section. Another feature in this building is that all the six mid-landings of the main stairs are cantilevered out to the bays of 3.5 x 1.6 mtrs. These are the spaces to accommodate store rooms, washing machine, and maid/staff rooms. Each of these are also attached with toilet bay of 1.6 x 1.8 mtrs. at every mid-landing.
Steel, as a prime structural material, is presumed to be expensive over conventional RCC structures. True, the numbers in the construction of these structures are on higher side by about 10 per cent, but, the end product compensates the costs by virtue of saving in time and strength despite its slenderness and organized work ethics. This project is a humble experiment in using steel as a structural material for residential typologies and promises to go a long way.
ARCHITECT NITIN KILLAWALA, Principal, Group Seven Architects & Planners Pvt Ltd
I was always fascinated with steel as a material, although I never got the opportunity to design a steel building for any of my clients, I thought of designing my own house with steel that will last for many years, and at the same time, provide structural aesthetics to the building. Today, not all clients take the risk of making a steel building, unless they have some proven records and examples to analyze the advantages. Normally, in a conventional project, floor by floor is constructed, but here, because it is a steel building, three floors are constructed together. The more we start building such structures, the more ideas and techniques we will develop
SHABBIR DALAL, GM – Designs, Shanghvi & Associates Consultants Pvt. Ltd.
For floors we could have chosen traditional type insitu concrete slabs but due to reduced time required to fix shuttering, cutting & fixing of steel rebars and cast each floor it was decided to adopt metal decking slab as it will avoid labour required to prepare , no propping fix formwork and by using factory made readily available welded wire mesh time requiring for fixing steel bars was avoided which has reduced the period required to finish the floor. Above all lesser waiting time for setting of concrete, no props had given contractor more flexibility to carry out other activities.
Architect : Group Seven Architects & Planners Pvt. Ltd.
Structural Consultant : Shanghvi & Associates Consultants Pvt. Ltd.
Structural Steelwork : PSL Ltd. & JSW Structural Metal Decking Ltd.