'Concrete buildings more vulnerable to quakes'

Randolph Langenbach is an expert on earthquakes and disaster recovery. A fellow of American Academy in Rome and consultant to Unesco on building conservation, Langenbach visited India after the Bhuj earthquake in 2001 and is currently in Kashmir. He tells Maneesh Pandey that the damage can be minimised by using better building techniques:
Q What are your impressions of the Muzaffarabad quake?
So far, I have learned from Prof C V R Murty of IIT-Kanpur who recently completed a reconnaissance trip in the area that the traditional Kashmiri dhajji dewari construction has survived relatively intact, while more recent buildings constructed of rubble stone without wooden frame or wall tiles have fallen.
In this traditional Kashmiri cons-truction, the walls are composed of a timber frame with masonry filling in between. Despite the rela-tively thin walls of this system, the confinement of the masonry by the wood beams and columns allow the buildings to sway in an earthquake without collapsing.
Q Did you notice something similar in Bhuj?
Unlike many recent earthquakes that seem to affect parti-cular types of structures, the Bhuj earthquake had a profound effect on structures of all types, from ancient to modern, traditional masonry to contemporary reinforced concrete. In Anjar, I found that almost every building in the historic centre had been destroyed.
But I noticed that buildings with balconies remai-ned standing. When there is a balcony, the beams go through the wall to hold it, locking the wall to the floor, one of the basic seismic mitigation rules.
The critically important rule is the floors and roof be firmly attached to the walls so that the walls are held together and the building will work as a single unit.
Q Do building designs and construction patterns in India need a review in the wake of quake threats?
Yes. It is well known that 80 per cent of the people at risk of death or injury in earthquakes in the world today are occupants of reinforced concrete frame buildings. In Ahmedabad, the newer buildings fared worse than the older ones because they made a zoning law that encouraged using the bottom level for open parking which makes the buildings weak at that level.
RC is a good material only when used scientifically, which is rare in many countries where it is used as the common 'default' system for all types of housing.
The earthquake areas in the US are less at risk not because all cons-truction is better, but because cheaper and poorer construction in that country is always of wood frame, not of reinforced concrete.
Q Is it time to research quake-resistant models for cities?
That would be wise. Construction is a manifestation of a culture just as design is. Appropriate and potentially sustainable solutions can be found within one's own culture.