Development of design method for composit columns with several encased steel profiles under combined shear and bending

Abstract

The present paper aims to develop a design method for ―hybrid‖ columns with several encased steel profiles. Particular attention will be paid to shear (longitudinal and transversal) resistances because preventing shear failure is one of the major concerns when designing a composite structural member. Experiments conducted with simple encased steel profile shown that the shear failure generally involves two possible failure modes: (1) the diagonal shear failure, which closely resembles the shear failure of an ordinary reinforced concrete structural member; and (2) the shear bond failure, which results in cracks along the interface of the steel flange and concrete. For a composite member, the shear bond failure can be critical when the steel flange width is large and approaching the overall width of the composite section [9]. Some tests carried out in Japan have shown that shear bond cracks along the interface of the steel flange and concrete are responsible for early failure [10]. For this reason, in this paper a method for the calculation of the number of connector to ensure the full interaction between steel profiles and concrete around is firstly proposed. Then a strut-and-tie model is developed to evaluate the transverse shear resistance taking into account the contribution of the steel profiles. Finally, a hybrid column with three steel profiles is designed using the proposed method and the design resistance values are compared to the ones obtained by an Abaqus FE model.