Seismic Design and Retrofit of Bridges

This book should be of interest to practicing bridge designers and researchers investigating the seismic design of bridges. It is appropriate for graduate courses or upper level undergraduate courses in seismic design of bridges. The approach relies heavily on the principles of capacity design, where a strength hierarchy is established in a bridge to ensure that damage is controllable and occurs only where the designer intends. This approach, which is well established for seismic design of buildings, has been extended and modified to reflect the special demands and characteristics of bridges. Particular emphasis is placed on designing adequate displacement and ductility capacity into new bridges, with less significance placed on strength. The book is developed around two alternative design strategies: the traditional force-based approach where force levels are related to acceleration spectra, with checks to ensure adequate displacement capacity exists, and the newer displacement-based design approach, where displacements are the starting point in the design. Introductory chapters discuss design philosophy and its impact on the performance of bridges in recent earthquakes, seismicity and soils effects, including liquefaction, in a form facilitating understanding by structural engineers, and the importance of rational consideration, from a seismic design viewpoint, of the various structural configuration possibilities in the conceptual design phase. Extensive discussion of analysis is provided in Chapter 4, with emphasis on the importance of realistic modeling assumptions and appropriate choice of analytical tools. Chapters 5 to 8 provide detailed information on the design of new bridges and the assessment and retrofit of existing bridges. A separate chapter is devoted to design and retrofit using seismic isolation and dissipation devices. Many design and analysis examples, some quite extensive in scope, are included. Design aids in the form of charts and tables are also provided. An index is provided.