Abstract: Based on the flexural tests on the FCSR(flange-channel steel roof) specimens， the working mechanism and failure mode of the specimens were investigated. In order to study the influence of the key parameters， including the tube thickness， the flange thickness， the compressive strength of the concrete and the spacing between the tubes on the flexural behavior of the specimens， finite element models of FCSR specimens were established by using the ABAQUS software. The results indicated that the lateral stiffness of the specimen is high and the failure mode is obvious ductile failure. The wall thickness of the steel pipe and the concrete strength may have certain influence on the bearing capacity of the specimen， while the thickness of the flange plate has no obvious influence on it. It is also found that the spacing of the steel pipe can affect the bearing capacity obviously. The research results may provide some basis for the application of the new pipe roof structure.

Key words: pipe roof, concrete-filled steel tube, channel steel, flexural behavior, numerical analysis