THE EFFECTS OF CONNECTIONS ON STRUCTURAL CAPACITIES OF CONCRETE FILLED CIRCULAR TUBES UNDER REPEATED AXIAL LOADS

Abstract

This paper describes the structural potential of various end connections to concrete filled tubes (CFT) which are used as axial force resistant members under earthquake loads. An alternatively repeated axial loading test was conducted for CFT members which were jointed at both ends by flange joint connections, flat gusset plate connections, or cruciform gusset plate connections. The CFT member was made of a cold formed steel tube with the diameter to thickness ratio of 20, 30 or 50 and normal concrete of the compression strength 30 MPa. The test has revealed that every connection has a potential to bring out the full structural capacity of CFT members, although connections would be imposed the repeated axial forces and also severe bending moments by cyclic flexural buckling of the members.