From colonial structures such as the Fort St. George to single pier flyovers and 20-storey high-rise buildings springing up in the suburbs, there is a need to check their quake resistance and carry out seismic retrofitting, said A.R. Santhakumar, an authority on earthquake engineering.
Delivering the Prof. P. Purushothaman Memorial Lecture at Anna University on ‘Earthquakes in Chennai: How prepared are we now?' he said Fort St. George, the seat of power in the State, would not withstand earthquakes of Zone 2 intensity. (When the codes for earthquake were revised in 2002, Chennai was moved up to Zone 3 up from Zone 2 as it was found to be more vulnerable). “No effort has been made to strengthen it.”
Similar is the case of the Madras High Court buildings. In Ripon buildings, modifications have been suggested as part of extensive rehabilitation, but as of today it was also vulnerable, said the retired professor of Anna University.
The thickness of the shear walls, the ground floor car park and use of flat slabs in high-rises were also quite vulnerable to earthquakes, as they would not able to resist the “lateral load.”
A study of eight modern apartment buildings in the city done by him revealed that seven of them were not earthquake-resistant, he said. The single-pier bridges in the city on Pantheon Road, Royapettah High Road and TTK Road suffered from “functional vulnerability” to earthquakes, he said and showed slides featuring photographs of the collapse of quake-hit bridges with single-pier design. A few other bridges needed seismic arresters to prevent collapse. The common problems he noticed were inadequate planning, design and application, poor code compliance, non-engineered buildings, inadequate detailing of reinforcements, extensions, alterations and encroachment.
Not all buildings would fall during earthquakes. The government was reinforcing and retrofitting the structures in a phased manner due to time, cost and usability factors, the professor said.
