Displacement-based seismic design has now come of age, especially for buildings. This report attempts to contribute to it, by focusing on special subjects which are crucial for its further advancement. It is divided in two Parts: one for buildings and another for bridges. Both parts have a chapter on the estimation of displacement and deformation demands and another on component force and deformation capacities.
For buildings, the part on analysis for displacement and deformation demands evaluates nonlinear analysis methods and the corresponding modelling at various degrees of sophistication, on the basis of experimental results (including identification of model parameters affecting reliability of deformation predictions) and compares nonlinear dynamic to linear analyses (static or modal) for irregular in plan buildings. It covers also soil-structure interaction in 3D, including uplift. It concludes with a description of the latest advances in adaptive pushover analysis for irregular buildings. Tools for the estimation of displacement and deformation demands are given, in the form of effective elastic stiffness of concrete members for use in linear analyses emulating nonlinear ones and of ductility-dependent equivalent damping. The chapter on component force and deformation capacities proposes acceptance and design criteria in terms of deformations at various performance levels, for concrete members in uni- or bi-directional cyclic loading.
The Part on bridges starts with an overview of displacement-based design methodologies for them, including evaluation of iterative procedures and proposals for the design of bridge piers directly on the basis of displacement and deformation demands, without analysis iterations. The chapter on estimation of displacement and deformation demands includes nonlinear analysis (static or dynamic), as well as the latest advances in adaptive pushover analysis for bridges. It also uses test results and numerical approaches to develop tools for the analysis, e.g., the secant-to-yield stiffness and the equivalent damping of concrete piers. The chapter on component force and deformation capacities focuses on concrete piers, developing simple rules for the estimation of their flexure- or shear-controlled cyclic ultimate deformation, on the basis of test results and numerical analyses. It also has a part devoted to seismic isolators, dealing with the evaluation of their displacement and re-centring capacity and the effect of exceedance of isolator displacement capacity on the bridge seismic response. The effect of the variation of the axial force of friction pendulum isolators on the response of the isolated bridge is also studied.