DYNAMIC COLLAPSE BEHAVIOR OF BRACED STEEL FRAMES TESTED BY SHAKE-TABLE EXCITATIONS

Abstract

 Dynamic collapse behavior of braced steel frames under mega-earthquake ground motion exceeding the design basis one was investigated. Firstly, shake table tests using two types of braced steel frame specimens with different collapse mechanisms were carried out to examine their dynamic collapse behaviors as well as to confirm the accuracy of FEM analysis. As a result of the shake table test, in the collapse mechanism accompanied by the brace buckling, the maximum displacement and the residual displacement did not increase sharply even after series of multiple seismic excitations. On the other hand, in the collapse mechanism with compression fracture where local buckling in the segment occurred at the base of the column, remarkable increases in the maximum displacement and the residual displacement were simultaneously observed. Numerical analysis precisely reproduced the experimental results, and the pushover analysis provided the collapse modes of braced frame specimens.