Experimental Study On Torsional Behavior Of CFS Strengthing RC Box Beams Subjected To Combined Action Of Bending-Shear-Torsion

In this paper, five experimental models of box beams are designed andmanufactured according to the current codes of "Technical specification forstrengthening concrete structrues with carbon fiber reinforced polymer laminate(CECS146:2003)" and "Code for design of concrete structures(GB50010-2002)", fourof them are strengthened by Carbon Fibre Sheet ,and the experimental research usinghydraulic servo actuator is performed to research the behavior of these memberssubjected to the combined action of bending-shear-torsion. To draw the reinforcementresult of CFS, this paper makes a comparison of the torsion strength, the torsionalstiffness and the flexural rigidity. And to research the working mechanism of the boxbeams under the combined action of bending-shear-torsion, the stress changes oflongitudinal bar and hoop and the strain curves of CFS on different sections are alsoinvestigated. By employing the spatial truss model and the code for design, the resultsof calculate are compared with the testing value, and then find out a good designmethod of strengthening the box beam subjected to the combined action ofbending-shear-torsion with CFS. Finally, some conclusions are given that the torsionstrength and the ductility of the box beam can be improved effectively bystrengthening with CFS, and the torsion strength of the CFS strengthening concretebox beam can be calculated accurately when using the spatial truss model, and theresults can reflect result of strengthening when calculating by the code, so this methodcan be applied to the design of the CFS strengthening concrete box beam.