The earthquake that jolted Nepal and parts of Delhi, Bihar and West Bengal has put the spotlight on the safety of buildings. But a look at the construction standards prescribed by civic agencies in the Capital and their implementation raises serious questions about structural safety in Delhi.
The civic corporations had in 2011 made it mandatory for residential complexes and private buildings to have stilt parking. But the Central Public Works Department says buildings with stilt parkings are dangerous.
An earthquake manual titled, ‘Handbook on seismic retrofit of buildings’ released by the CPWD in April 2007 has listed stilt constructions as one of the major deficiencies of building masonry.
“A ground storey without walls (for car parking) can cave in,” reads the safety manual.
In their defence, the civic agencies said that a proper design, where the building’s weight is amply balanced on the pillars, makes it fit to bear tremors. However, builders only have to submit an undertaking that says the buildings are well designed and follow safety norms.
Engineers at CPWD, however, sound the alarm bells. “The walls are the most important part of the building that absorbs shock in case of high seismic tremors. Architecturally, it is generally not advised to construct open ground storey buildings in areas that come under the high earthquake risk zones. Delhi falls in zone four, which requires buildings to have the support of walls,” said a senior engineer of CPWD.
In 2011, the civic agencies had made it mandatory for all new buildings with an area space between 100sq meters and 1,000 sq metres to mandatorily have stilt parking before it is approved by the building department.
“The buildings that came for approval after 2011 required to accommodate its parking space within the floor space. However, we also made it mandatory that reinforced concrete frame buildings cannot be higher than three floors and the beams and columns are required to bear the weight of the structure,” said a senior civic body official.A study conducted by IIT Delhi says after the Bhuj earthquake in 2001, over 100 open ground-storey buildings collapsed in Ahmedabad. The response spectra obtained at a site in Ahmedabad shows peaks at about 0.35, 0.55 and 0.8 sec. This means buildings with 6-10 floors, supported by beams and columns, could not bear the shaking even for a few seconds and collapsed, the study read.