Experimental study on ultimate strength and ductility of concrete filled steel columns under strong earthquake

Abstract

After the shock of the Hyogo-Ken Nambu Earthquake, a newly revised Japanese Seismic Design Method for Bridge Structures requires that steel bridge piers should not suffer serious damage due to such strong earthquakes. As one of the suitable methods to meet this requirement, a method of inserting an additional steel tube into the inside of a steel bridge pier can be considered. In this method, the ductility of the bridge pier is significantly enhanced, if the cross section is designed in such a manner that the axial compressive load, caused by the dead load of the superstructure, is mainly carried by the inner steel tube and the local buckling of the outer steel pier as well as the column buckling of the inner steel tube are prevented by the encased concrete between them. To investigate the ultimate strength and ductility of these concrete-filled steel box columns under strong earthquakes, an experimental study is executed.