Building Capacity in Delhi to Seismically Retrofit Existing Important Buildings

摘要

India’s fast-growing capital city of Delhi, home to over 14 million people, faces substantial earthquake hazards from both distant, large-magnitude earthquakes in the Himalayas and smaller, local events. The Delhi metropolitan area contains an amalgam of existing building types: old and recently constructed, illegally built and well-designed, humble brick houses and gleaming new high-rises. Many of these buildings are seismically vulnerable and will threaten the lives of Delhi’s inhabitants, if a major earthquake strikes. To help reduce Delhi’s earthquake risk, GeoHazards International (GHI) conducted a project to build the capacity of the Delhi Public Works Department (PWD) to assess and seismically retrofit vulnerable existing buildings that have important post-earthquake functions. Improved seismic performance of these buildings both protects the government employees working there and enables them to respond more effectively to disastrous earthquake events. GHI utilized a practical learning approach, in which a peer review panel from India and the United States mentored Delhi PWD engineers as they seismically retrofitted government buildings. Project buildings included the main offices of the Government of the National Capital Territory of Delhi, the police headquarters, a hospital, a school that serves as a relief distribution center, and the disaster management authority offices. The buildings had a range of structural systems, configurations, performance goals, and functional requirements. Structural systems included unreinforced masonry (URM) bearing wall, reinforced concrete frame with URM infill, reinforced concrete shear wall, and a combination of concrete frame and URM bearing wall. Delhi PWD engineers learned to apply performance-based earthquake engineering concepts, assess and design retrofit schemes for existing buildings, address issues of disruption and user requirements, rectify falling hazards, and apply risk reduction options other than retrofit (such as changing a building’s use or replacing it with a new earthquakeresistant building). This paper discusses the technical challenges and lessons learned during this project, and recommends measures to improve future projects that transfer knowledge to mitigate risks posed by existing buildings.