Experimental and numerical investigation on non-welding CFDST joint for seismic evaluation of moment resisting frame

Abstract

This paper aims to evaluate the seismic performance of concrete filled double-skin steel tubular (CFDST) frame structures. An experimental investigation on internal joints to CFDST columns was conducted to assess their seismic behavior, in which non-welding connection method was employed to avoid possible premature welding fracture. Experimental results declared that this type of joint behaved in a semi-rigid manner. Numerical models were then established to simulate the seismic performance of the joints. The moment–rotation relationship and shear behavior of panel zone were both accounted according to the component method and strut model, respectively. Subsequently, a CFDST moment resisting frame with non-welding connections (NWF) was numerically analyzed to detect its seismic response under design-based and maximum considered earthquakes. The numerical results confirmed that the NWF could lower the seismic response in terms of base shear force and joint moment compared with namely rigid frame (NRF). It also verified that the maximum story drift ratios of the NWF were higher than those of the NWF. Increment dynamic analyses (IDA) were also performed to evaluate the collapse behavior. Furthermore, a detailed discussion was conducted to analyze the influence of joint stiffness on global behavior of the NWF. The analytical results verified that this type of NWF had satisfied seismic behavior and excellent anti-collapse performance. More importantly, the NWF could conveniently adjust the stiffness of each story by varying the stiffness of the non-welding connection to decrease the story drift and to achieve a uniform story drift distribution.