Experimental study on tensile fracture mechanism of butt joints in multi-celled CFST walls

Abstract

Multi-celled concrete filled steel tubular walls (MCFSTWs) have been widely used in engineering practice. A high MCFSTW can be constructed by assembling two medium-height wall segments that are butt welded with the connector. At the connecting part between two wall segments, the connector, welding seams and steel plates of upper and lower wall segments form the butt joint. Since the butt joint is susceptible to tensile fracture, it is necessary to investigate its tensile fracture mechanism. In this paper, 12 specimens representing different parts of the butt joint are tested under tension and they include 6 types with different configurations. These specimens are designed by using connectors with different shapes and considering different welding conditions. The test results are analyzed and validated against the numerical simulation considering the ductile damage criteria. Based on the reliable finite element (FE) model, a simplified model is established to study the fracture performance of the complete butt joint. Finally, reliable design recommendations based on the experimental results and supplement FE analysis are summarized for improving the tensile performance of butt joints in MCFSTWs.