This book will appeal to specialist engineers with enquiring minds and, in a broader sense, to all who live in buildings, especially those in a seismically active region. While the continual development of building codes permits the design of new construction to resist earthquake loads more effectively, a major problem is that buildings which may once have conformed to past seismic codes become structurally unacceptable according to today's codes and need upgrading or `retrofitting'. Poor construction methods also result in buildings that do not conform to any codes. Existing `vulnerable' buildings that require strengthening in earthquake-prone countries immensely outnumber all recent construction. The `health' of buildings thus requires assessment and rehabilitation. Seismic assessment ranges from the cataloguing of `danger symptoms' in individual buildings to structural analyses involving finite element procedures and refined statistical analyses incorporating expert systems, stochastic processes and predictions from available databases. Structures have to be rendered fit for earthquakes, and this book goes a long way towards showing why and how, offering the results of cutting-edge research in the area and presenting innovative methods that enable system improvement while the structure remains in use.