Experimental Studies on the Elastic-Plastic Behavior of Braced Frames under Repeated Horizontal Loading. Part 2 Experiments of braces composed of steel circular tubes, angle-shapes, flat bars or round bars

Abstract

Experimental studies are conducted to investigate the hysteretic restoring force characteristics of steel braces built in a structural frame and the effect of the local behavior on the failure. Test specimens of the braces are made of steel circular tubes, angle-shapes, flat bars and round bars. The fundamental properties of hysteretic characteristics of braces with various types of cross sections are extracted from the experimental results. The shape of hysteresis loops, the change and the deterioration in load carrying capacity and energy absorbing capacity under cyclic loading are examined and compared with those of the braces with an H-shaped cross section which was reported in Part 1. It is noted that the reduction of ductility in the plastic deformation range due to cracking at the end-joint portions where stress-concentration might occur in the case of circular tube braces and cracks caused by low cycle fatigue at the end section where bolt holes reduce net area of a cross section and at the locally buckled mid-length portion in the case of angle braces are ascertained.