Most of Chennai’s airport woes are simply design flaws, says Francis Santiago. Are many of the city's buildings guilty of this sloppy approach?
Chennai’s new domestic terminal is making news for all the wrong reasons. It should have been the latest addition to the city’s growing list of world-class infrastructure facilities, but instead it is a mess, with reports of a new fiasco every day. Portions of the false ceiling fell down in the departure area, water is dripping from the air-conditioning systems, glass panels have cracked, the toilets are unsanitary, and escalators and elevators inefficiently planned… it’s a long list.
Large-scale projects involve rigorous planning and scheduling and, even when complete, might not always be perfect. This is true worldwide, even in developed countries. For instance, the earthquake anchor rods used in the ongoing replacement project of the San Francisco-Oakland Bay Bridge fractured during construction and were found to have manufacturing defects.
India’s economic growth in the last two decades has created the impetus to build structures of global standards.
Contractors put in considerable effort to bring in new components and material. Many multinationals have set up manufacturing units here. As new components come in, the design parameters of each need to be studied carefully. Had this been done, and contractors strictly followed design requirements, Chennai’s new airport might not be in so much trouble.
All fall down
Take the issue of the ceiling panels. Airport authorities have attributed the reason to a wind tunnel effect near the departure gate. Did the design specifications not identify the wind pressure that the ceiling system should be designed for? A structural engineer from IIT-Madras has called it ‘a typical case of engineering defect’.
Chances are the design specifications missed identifying the wind factor. Wind tunnel effect is a known design issue for structures and components built near doorways and there can be little excuse for missing it.
Armstrong USA, which provided the false ceiling, indicated after the ceiling panel collapse that it had given a ‘not satisfactory’ report during installation. Why was this report from the supplier ignored?
A later statement by airport authorities said the panels were replaced in a record time of 17 hours. However, it does not specify how the reinstallation was carried out. If similar in design to the earlier one, the panels could collapse again under strong winds. In fact, latest news reports point out that several roof panels are hanging loose.
Second is the issue of the cracked glass panels. Initial reports suggest factors such as thermal effects, and inferior glass or sealant. From a structural standpoint, the fault could lie elsewhere. Glass facades are designed to provide an envelope around the building and do not provide structural support to the roof or floor, which is done by columns and beams. These beams bend or deflect when a load is imposed, and the glass panels have to be customised to accommodate this deflection. The play is specified in the design drawing itself.
India does not yet have design and performance standards for glass systems unlike, say, the US, which has standards to ensure wind and earthquake load compliance. An IIT-Madras professor has called for glass companies working in India to comply with available international standards, but to no avail. Until this happens, we will continue to hear shattering stories about glass.
As for water dripping from the air-conditioning system, officials have suggested that this can be alleviated by the use of sun-film on one side of the building. Airports have been built in harsher climates than that of Chennai. This issue should have been addressed by the architect and the mechanical engineer in the design phase itself.
More in store?
A larger issue could be looming ahead. The steel structural framing of the roof and the glass façade seems to lack adequate earthquake resistance. Along the longer direction of the building, the frame does not seem to comply with the best design provisions of a brace frame. Along the shorter direction, the trussed roof, meant to serve as a moment frame, may not have the resistance and strength to prevent an eventual structural collapse in a severe earthquake.
Large projects involve thousands of crores of rupees. Paying a marginal premium upfront during the crucial design phase, followed by careful monitoring during construction to ensure compliance with the drawings seems an instinctive rule to apply. It is surprising how often it is followed in the breach.
3. How can uniform building standards be imposed on developers and architects?
2. Glass panels have to be customised to accommodate any deflections arising from loads.
1. Why wasn’t the false ceiling designed to counter the wind tunnel effect?
(The writer has a Master’s in Civil Engineering and is a licensed engineer in California. He has extensive experience in international projects, and runs a structural consultancy company in Chennai. Mail him at firstname.lastname@example.org)