What does earthquake ‘resistance’ mean?
Buildings are categorised on the basis of the damage they have sustained in earthquakes
Afully operational level of earthquake resistance’ means that despite being shaken by an earthquake, a building, its contents and utilities remain undamaged. Its function is also not disrupted.
An ‘ immediate occupancy level of earthquake resistance’, is defined as a building, its contents and utilities being shaken predominantly in an earthquake with only minor damage; the use of the building and facilities not restricted after the event so that its functioning can be resumed immediately after the earthquake.
Life safety level of earthquake resistance is defined by the National Disaster Management Authority as that the building, its contents and utilities being shaken severely in their nonlinear range of behaviour. Significant damage occurs, but the building remains within its reserve capacity and does not reach a state of imminent collapse. Use of the facility is restricted after the earthquake until detailed structural safety assessment is done to ascertain the suitability of the building for retrofitting.
Collapse prevention is defined as that the building, its contents and utilities being shaken severely in their nonlinear range of behaviour and major damage occurring. The building does not have any additional reserve capacity and is in the state of imminent collapse.
“Till date all buildings in the country are being sold/ leased/rented to public by just mentioning that the building is earthquake-resistant and without mentioning the category of the earthquake resistance, ie fully operational, immediate occupancy, life safety or collapse prevention or elaborating on the definitions of each of these categories. The difference between the performance levels of the four categories of earthquake resistant buildings is so large that keeping a customer in the dark is a blatant breach of his consumer rights of ‘right to be informed’ and ‘the right to consumer education’,” says Sandeep Donald Shah, a structural engineer from Miyamoto India.
There should be strict rules for buildings to have an engraved metal plate, of one feet by two feet, mentioning that the building is earthquake resistant – collapse prevention or any other category or ‘earthquake
resistance unknown,’ he says.