Axial stiffness of concrete filled rectangular steel tubular (CFRST) truss joints

The flexural stiffness of the truss is affected by the joint stiffness. Due to the infilled concrete, the axial stiffness of the concrete filled rectangular steel tubular (CFRST) truss joints is different with the brace under tension and compression. In order to study the axial stiffness of the CFRST joints, the calculating models were developed by employing the component method. The validated finite element (FE) method was proposed to build FE models of joints. Parametric analysis of the inclined angle theta of the brace and the gap g of K joints was performed. Nonlinear fitting of the undetermined factors of stiffness equations was conducted based on FE results. Consequently, calculating equations of the axial stiffness of CFRST T, Y and K joints were adopted to predict the flexural stiffness of CFRST trusses. Results indicated that the predicted flexural stiffness of the truss coincided well with the tested results. The effect of the joint on the flexural stiffness of the truss was well considered. (c) 2021 Elsevier Ltd. All rights reserved.