T-JOINTS IN RECTANGULAR HOLLOW SECTIONS SUBJECT TO COMBINED ACTIONS

An extensive test program on a range of cold-formed rectangular and square hollow sections subjected to combined bending and concentrated force is described. The concentrated force was applied by welding a square hollow section (called the branch member) to the center of the member under test (called the chord member) and perpendicular to it. The chord member was simply supported with the concentrated force at the center of the span. The span was varied in order to determine the interaction relationship between bending moment and concentrated force. Tests under pure moment and pure concentrated force were performed for control purposes. The ratio of the width of the branch member to the chord member (beta) used varied from 0.5 to 1.0 so that failure modes ranging from local bending and buckling of the face of the chord member to web crippling were observed. In addition, the thickness of the chord-member sections was varied so as to produce a range of section slenderness and failure modes from buckling to yielding. The results are compared with the design procedures in the 1986 AISI Specification, Australian Standard AS1538 of 1988, CIDECT Monograph No. 6 of 1986, and other proposed procedures. In addition, a comparison with plastic mechanism models is provided.