Seismic demand evaluation procedure for concrete-filled steel columns

Abstract

This chapter presents the seismic demand predictions of concrete-filled steel columns mainly used in highway bridge piers. Two types of dynamic analysis procedures are proposed: a SDOF system analysis method using force-displacement hysteretic models derived based on the static pushover analysis results, and a fiber model analysis procedure that involves with individual cyclic stress-strain relations of steel and confined concrete. Two types of hysteretic models, namely bilinear and trilinear models, are used in the case of former method. The analyses are carried out using both procedures for specimens tested by pseudo-dynamic testing procedure. The accuracy of each method is checked by comparing the predicted maximum and residual displacement demands with those of the test. It is found that the maximum displacement demand predicted by the fiber analysis, and that involved with the trilinear hysteretic model, exhibits good agreement with the test results. However, the predictions made using the bilinear hysteretic model do not agree well with the test results. In addition, the residual displacement demands predicted through both procedures are found to be unsatisfactory. Therefore, an empirical equation is proposed to predict the residual displacement demand in terms of the maximum displacement demand that can be computed by the either method proposed in this study.