Seismic Risk Reduction for Schools with Stone Slab Roof Systems in Delhi

Delhi, India faces substantial earthquake hazards from both distant, large-magnitude earthquakes in the Himalayas and smaller, local events. Delhi has many seismically vulnerable school buildings, in both government and private schools. GeoHazards International (GHI) has been working for several years with the Government of the National Capital Territory of Delhi and private sector partners, in order to reduce the earthquake risk to Delhi's schools. In the course of these efforts, GHI encountered a type of "semi-permanent," unreinforced brick school building with a particularly vulnerable type of roof constructed from steel I-beams and heavy, flat stone slabs. The stone slabs and beams are not attached to each other or to the supporting brick walls so that the building could, theoretically, be dismantled and moved to a new location. However, this lack of connection means that during strong shaking, stones could fall on students and teachers. This paper describes the unique design problem that these unusual semi-permanent buildings pose and the retrofit and conceptual new construction solutions that could reduce the earthquake risks that the buildings pose to students and teachers.