Experimental study on a new V-cut RBS and CFT connections with bidirectional bolts under cyclic loadings

Abstract

This paper presents experimental investigation on evaluation of performance of a new type of steel reduced beam section (RBS), designated as V-cut, and on its role in improving overall safety of RBS-CFT connections subjected to cyclic load. Detailed design steps adopted for design of the V-cut RBS with lower depth of cut, as compared to that in the conventional radius cut RBS, are reported in this paper. Behavior of two types of steel RBS and concrete filled tube (CFT) connections with bidirectional bolts were examined. An experimental study was performed to compare the performance of V-cut RBS with that of the conventional radius cut RBS under cyclic loading. It exhibited improved hysteretic behavior, and the new RBS-CFT connection is found to be semi-rigid in nature. Test results show that the energy dissipation in the composite steel connections with V-cut RBS is higher than that with radius cut RBS. The application of V-cut steel flange beam effectively enhanced ductility and reduced the residual torsional deformation. It reached a rotational capacity of 0.04 radians without any damage in the joint panel region, and thereby meets the seismic provisions of the AISC as a special composite moment-resisting frame. Further, a simplified numerical simulation of force-deformation hysteretic behavior of RBS-CFT connections was carried out using OpenSees software. Simulated force-deformation hysteresis loops are found to be in close agreement with those obtained from experimental investigation.