The Ultimate Bearing Capacity Of Rectangular Concrete Filled Steel Tubular T, Y-type Compression Node Study

The Concrete-Filled Rectangular Hollow Sections (CFRHS) T- and Y-Connections are the novel kind of welded-truss connections, which have not yet been concerned by the existing codes or specifications in China. But as the Rectangular Steel Sections are increasingly widely used, how to predict the ultimate strength of CFRHS connections is becoming a serious problem. The research of this thesis is aimed at offering convicting evidence for the coming Technical Specification for Structures with Concrete-Filled Rectangular Steel Tube Members. Moreover, popularizing such connections is expected.The behavior of concrete-filled T- and Y-connections is examined by means of nonlinear Finite Element Analysis (FEA). The connection is modeled using shell, solid and contact elements, and analyzed concerning material, geometric and contact non-linear.Tests on 8 filled and unfilled connections are carried out. The results of tests show that the method of FEA is accurate in simulating such connections. It is also found from the tests that the ultimate capacity of connection is greatly affected by the ratio of the width of branch to that of chord, the thickness of chord and the angle between chord and branch.FEA on 34 connections have been taken to find out the parameters that will decide the behavior of connections. Based on that, the available ranges of the parameters discussed are established. Finally, a set of equations is proposed to predict the ultimate strength of such connections, the results of which accord with that of both tests and FEA.