Architect's Role in Building's Seismic Performance
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building science SKC Varthi K AND DR DK PauL ARCHITECT’S ROLE IN BUILDING’S SEISMIC PERFORMANCE Enhancement of the seismic performance of a building should be the priority of the architect as well as the client. Common irregularities brought in to entertain unnecessary area encroachment should be avoided building is a combination of art and science, which are put together to function as a living structure. The increasing complexity of integrity ensures simpler functioning of the building. Therefore, building science is an unending process, which achieves its perfection at infinity. There is no end to the Apossibilities for improvement. Building construction is a complex phenomenon involving many param- eters and factors, such as planning, designing, construction, management, logistics and budgeting. Therefore, it clearly requires expertise from various fields and brainstorming by many specialists, professionals and technicians, including architects, civil engineers, project managers, contractors and various other authorities who contribute in sequential or parallel processes involved in construction. They work together to produce a design, which is simple, sustain- able in functioning, aesthetically pleasing and structurally strong. Therefore, the three most important aspects of building design are: (i) Function (ii) Form and (iii) Strength. American architect, Louis Sullivan, referred to as the father of modernism and skyscrapers, stated in one of his poems, that ‘the form follows function’. This statement is now a doctrine for modern architects. Here, ‘function’ refers to the usage of the building and ‘form’ refers to its overall geometry, composed in an aesthetically pleasing manner in keeping with the requirements of the user or intended functions. 36 ARCHITECTURE - Time Space & People August 2014 The practicality of a structure is building structure. At the appropriate usage of a single building for multiple more important than the aesthetics. stages, he brings in the civil engineers, purposes is yet not acknowledged in This could not be more significant in project managers, contractors, other the Indian codes, giving rise to the today’s world where the natural and specialists and technicians to work issues of strength and durability. In anthropogenic catastrophes have on and produce a living space. It is a seismically active area, this issue is hit the world in the form of deadly the architect’s duty to look after the further aggravated. disasters. These disasters, such as purpose of the building, area require- earthquakes that severely damage ments, accessibility, ventilation and Indian Scenario buildings, prove fatal to life. However, associated configuration, and so on. In India, earthquakes are still viewed the truth remains that it is not the He creatively configures the structural as rare events that occur once in a 100 disasters that are responsible for the and non-structural components in a years. In the face of such a conception, loss of lives, but the buildings that manner that ensures the durability of the client is unwilling to allocate a sig- are incapable of withstanding these the building in times of disasters, and nificant part of the budget on seismic disasters. Loss life can be drastically also gives it a unique appearance. strength, preferring to spend instead reduced by ensuring that the struc- The role of a civil engineer is to on architectural form, which costs tures of buildings are strong enough give enough strength to his ideas less and gives more habitable space. to bear the impact of earthquakes. and look after endurance and seismic As a result, more habitable space in Let us now look at the importance strength of the structural members. lesser area and superficial beautifica- of building performance, with respect For achieving a high degree of func- tion becomes the focus of building to architectural form and functional tional perfection, the plans may need design. The common configuration usage. The meaning of function may to be relooked at and improvised problems, mostly seen in the conven- vary on the basis of the context, several times by the architect and the tional construction system in India are person(s) and area. A country like engineer. In this process, the building as follows: India, ranking second in the world risks a trade off between architectural in terms of population, is extremely form and structural strength. The 1. SOFT STOREY AND susceptible to disasters. The weak architect, personally, gives more im- WEAK STOREY technological advancement in its portance to the functional use of the The ‘soft storey’ problem is the exis- building industry, is yet another issue. building. However, he has to go with tence of a building floor that possess- In such a scenario, defining ‘function’ the client’s wish to design the most es 70% lesser lateral stiffness than the can be quite a challenge! appealing form. At the same time, immediate superior floor or 80% lesser Ideally, buildings should be he has to create maximum habitable average stiffness of the three floors designed to serve different purposes. space out of the limited area at hand. above (Refer Figure 1). They should be: The client’s demand for innovative The ‘weak storey’ problem is the • Structurally strong designs forces the architect to go for existence of a building floor that pos- • Practical unconventional, asymmetrical and sesses 80% lesser lateral strength than • Suitable for use new creative building forms. Unfortu- the immediate superior floor. • Aesthetically pleasing nately, the Indian building regulations These deformities are found in It is up to the architect to take up and codes do not acknowledge such places, where more space with large the challenge of designing a build- forms. These codes recognize build- span (without structural obstruction), ing, which will not only serve all these ings with a regular square or rectan- is required, for example, parking purposes but also conform to building gular plan, symmetrical in horizontal lots, large assemble areas, shopping regulations, codes and budgets. The and vertical planes, with little liberty complexes and display areas with architect is solely responsible if the for innovation. Thus, in India, the large openings. These result from little building is not fit for the functional building designs are supposed to be consideration given to the strength of usage. He is also responsible for the very limited and rigid according to building with an intention of having form derived from the function of the these regulations and codes. Also, the maximum area to be occupied for use. August 2014 ARCHITECTURE - Time Space & People 37 building science This issue can be solved through Designing the ‘problem causing simple design intervention. A little building elements’ at the center or near consciousness regarding lateral the center of mass, without lining with strength and stiffness, and uniform the perimeter or providing uniform load distribution to structural mem- strength and stiffness to the perimeter, bers, in both horizontal and vertical can be an easy solution. There can be planes, would be enough to remove many other solutions possible, which such atrocities from new building may remove or at least decrease the designs. For the existing build- problem to a manageable extent in the ings, there are several solutions to early stages of design. choose from, for example, the use Fig. 1: Building with ground floor soft storey of additional columns, buttresses, 3. Re-entrANT CORNERS shear wall or bracing (Refer figures The buildings with shapes like L, T 2 to 5). and H or a combination of these tend to produce differential motions be- 2. VARIATION IN PERIMETER tween different wings of the building, STRENGTH AND STIFFNESS for the same earthquake force. This The issue of seismic strength results in differential concentration of arises when there is wide variation stress and torsion in different wings, Fig. 2: Addition of shear wall to existing in strength and stiffness of the making them vulnerable to breakage soft storey building perimeter. The building (Refer figures 7 and 8). Of course, this may appear to be geometrically effect may depend on a number of regular, but the design and factors like: planning of building elements • Characteristics of ground motion like elevators and staircases along • Mass of building one side of the perimeter makes • Type of structural system it seismically irregular. The center • Length of the wing and Fig. 3: Addition of extra columns to existing of mass shifts due to the extra aspect ratio soft storey elements and makes the structure • Height of wing and height/ vulnerable to damage (Figure 6). depth ratio Fig. 4: Addition of bracing to existing soft storey Fig. 5: Addition of external buttress to existing soft storey Fig. 6: Showing unbalanced front side of perimeter 38 ARCHITECTURE - Time Space & People August 2014 building on slopes are a few of them. avoided, or at least minimized up to a Location of other building elements, manageable extent where they cause such as a staircase, beam, slab or no harm to life or property. It is the girder framed at different heights of sole responsibility of the architect to columns by splitting them, can also be act wisely and understand the need possible reasons for the same. of structural congruity along with the Consideration of this issue during architectural form of the building. Fig. 7: Showing different plan forms designing of the building plan can The architect’s knowledge and susceptible to form re-entrant corners help eliminate the problem. For the understanding of zoning regulations, location of building elements placed building by-laws and seismic codes, at different heights of the columns, a put together, not only improve the new structural member or a wall can building design in the present but also be erected in order to take the load save lives from being harmed in the of those elements. This would help in event of some disaster in the future.