Title: Displacement-Based Seismic Design of Concrete Structures

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Publication: CIA

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Date: 2/13/2011

Abstract:
Conceptual problems inherent in conventional initial-stiffness force-based seismic design of concrete structures are outlined. It is noted that structural performance in terms of damage potential is related to strain or drift limits and does not correlate well with strength. As a consequence, structures designed by force-based criteria have non-uniform seismic risk. Displacement-based seismic design is offered as a rational replacement for force-based design. Following extensive recent research, a variant known as Direct Displacement-Based Design (DDBD) has reached sufficient maturity to be considered for routine seismic design. The DDBD procedure, described in this paper, is extremely simple, and aims to achieve, rather than be bounded by performance limit states defined by displacement limits. This essentially results in uniform-risk buildings, a result compatible with the concept of uniform risk spectra, which have long been accepted for seismic input. Application of the procedure to different structural forms, including concrete frame buildings, walls, dual wall/frame buildings and bridges, have been validated by extensive inelastic time-history analyses. A brief summary of the research is presented. It is shown that the design results follow trends that are often opposed to those resulting from force-based design, and are particularly favourable to regions of low to moderate seismicity, such as Australia.