Seismic vulnerability of monastery temples of stone masonry in Sikkim Himalaya

Abstract

Buddhist monasteries in the Sikkim region have conserved and portrayed the art of Tibetan and Chinese architectural style through centuries. These historic structures have sustained varied degrees of damage due to earlier earthquakes. Their performance in the recent Sikkim earthquake of M 6.9 on 18 September 2011 shows their high seismic vulnerability. A quick seismic assessment using certain simplified indices suggests higher vulnerability of damage for these heritage structures. A post-earthquake ambient vibration test established these monastery temples as shortperiod structures with fundamental period of 0.23 to 0.37 s. A finite element analysis of one of these temples has been done to study its dynamic behaviour. The response spectrum and static nonlinear pushover analysis highlighted vulnerable portions of stone masonry walls and provided useful insights for proper retrofitting to mitigate damage in future earthquakes.