Ultimate strength and ductility of partially concrete-filled steel rigid-frame bridge piers

Abstract

Concrete-filled steel tubes have wide range of applications in building and civil engineering structures due to their excellent earthquake resisting characteristics. In this study effectiveness of partially concrete-filled steel tubes (CFST) in rigid-frame bridge pier bents is examined in terms of their ultimate strength and ductility performances. The columns and beam of frames consist of an un-stiffened rectangular-shaped steel section. Pushover analyses of single columns and rigid-frames were carried out using beam-column elements associated with nonlinear stress-strain relations for both concrete and steel. The effect of filled-in height of single columns was first examined by comparing the ultimate displacement and the ultimate strength determined using an available failure criterion established for cantilever type concrete-filled steel columns. The optimum concrete-filled height of the single columns was found to be around 0.30 times the column height. The pushover analyses were carried out for three rigid-frames having different filled-in heights. The ultimate displacement and the ultimate strength of concrete-filled rigid-frame were significantly higher than those of the hollow section frame. The optimum filled-in height of rigid-frames was found to be around 0.15 times the total height of the frame.