Static Strength of Cracked Square Hollow Section T Joints under Axial Loads. I: Experimental

A series of static strength tests were performed on full-scale precracked square-to-square hollow section welded T joints. These joints were subjected under brace end axial load until failure using a special purpose designed test rig. An alternating current potential drop technique was employed to monitor the crack propagation during the tests. In addition, three sets of linear variable displacement transducers were used to record the crack mouth opening displacements. The tests were performed at room temperature; therefore, the material is on the upper shelf of the ductile-brittle transition curve where failure occurs in a ductile manner. In all these tests, a stable ductile tearing was observed with a small tearing region. Based on the yield line theory, the plastic collapse load is estimated, and then applied to the failure assessment diagram (FAD) of BS7910. The results show that BS7910 Level 2A FAD provides an adequate procedure for the assessment of cracked square-to-square hollow section T joints.