Assessment of nonlinear seismic performance of RC frames

Performance based seismic design procedures require enhanced computational models for evaluating deformation parameters. Performance of four reinforced concrete frames, designed according to Eurocode 8 specifications and having different number of stories, ranging from 4 to 10, is studied by means of a computational model based on the decompositions of a frame member into different sub-elements, each describing a different deformations mechanism affecting hysteretic behavior of critical regions. The effects of joint flexibility due to bar pull-out at the beam-column and at the column-foundation interface on the inelastic dynamic response of reinforced concrete frames are investigated. It is shown that joint flexibility can affect significantly the deformation parameters, with larger amplifications for the 4-story frame compared to those found for the 10-story frame. Therefore, enhanced modeling is recommended if performance based seismic design is to be used for design or assessment purposes.