Experimental Investigation and Design of Concrete-Filled Steel Tubular CHS Connections

Abstract

A series of tests on the concrete-filled tubular circular hollow section (CHS) connections is presented in this paper. Four types (T, Y, K, and KT) of 12 connections were tested. The tests covered two different chord wall slenderness ratios (D/t) of 60 and 75. The test specimens were first welded by steel tubes to form connections, and then self-compact concrete was filled in the main chord in full length. The material properties of steel and concrete used in the test specimens were measured. Each connection was tested to failure with the branch member loaded in axial tension. Punching shear failure of chord member was the main failure mode observed during the tests. The test results were also compared with current AISC design predictions, which are only for circular hollow section steel tubular connections. The design strengths predicted by the current AISC standard are shown to be quite conservative for the test specimens in this study. Therefore, the contribution of concrete should be considered in the design because it has a significant effect on the ultimate bearing capacity of concrete-filled CHS tubular connections.