Tests of rigid composite joints subjected to bending moment combined with tension

Abstract

Catenary action plays an important role in redistributing the internal loads and preventing progressive collapse of structures from happening when the structures are subjected to a sudden loss of a column. When catenary action is triggered, the beams are subjected to axially tensile forces. Thus the joints are under the state of bending moment combined with tensile force. To study the behavior of column–beam joints subjected to column failure, this paper presents an experimental study of five composite joints. In the test, three loading conditions are considered: bending moment, tensile force, and combination of bending moment and tensile force. The results indicate that the rigid composite joint possesses good ductility and rotation capacity which meet the requirements for the formation of “catenary action”. The joint also possesses good tensile capacity and deformation ability, which provides a reliable alternate load path. For joints subjected to a bending moment combined with a tensile force, the bending moment capacity of the joint linearly decreases with the increase of the tensile force. An envelope curve of the bending moment–tensile force is obtained which represents the plastic behavior of the joint under the combination of a bending moment and a tensile force.