Shear deformation and interface behaviour of concrete-filled CFRP box beams

A beam structure composed of CFRP box with infill concrete is studied for an application under transverse and axial loads. This paper highlights the shear deformation of box beams under empty condition and concrete-filled condition by simulating the beams tested in an experiment with finite element method. Firstly, empty CFRP box beam is studied. Shear deformation contributes with about 60% of total beam deflection. Furthermore, different analyses with perfect bond assumption and slip assumption are performed to investigate concrete–CFRP interface interaction in a filled beam. From these analyses, slip between concrete and CFRP is evident in the experiment. Consequently, the shear deformation of CFRP becomes very high and the stiffness of the beam is not improved even with concrete infill. Effect of axial load on friction mobilization and P-delta effect are also discussed in relation to the deformation behaviour of concrete-filled beams.