FE Simulation And Theoretical Analysis On Torsional Behavior Of FRP Strengthened-RC Beam Subjected To Combined Action

Port terminal plays an important role in national economy and social development. Thereinforcing of original wharfs has become an important issue due to the change of usingconditions and weakening of original wharfs after wharf structures are used certain number ofyears.FRP (fiber reinforced polymer) sheets are widely used in all areas of automotiveindustry and national infrastructure for their high strength, light weight, anti-magnetic,corrosion resistance and other excellent features. Especially in today’s civil engineering sector,the technology on pasting FRP sheets at external of reinforced concrete structures has becomemore widely used in various reinforcement structure for its easy construction and noadditional load, etc. Now, at home and abroad, there are few studies on FRP sheets-reinforcedconcrete beams under composite stress bending, shear and torsion, so related theories are notperfect.This paper analyzes and summarizes relevant information on existing twisted RC beamsso far at home and abroad, a nonlinear finite element model of CFRP-reinforced concretecomponents under bending, shear and torsions established by using finite element analysissoftware ANSYS. The model parameters such as layers’ number and pasting direction ofCFRP sheets are investigated and the influence of torsional capacity factors on the ultimatetorsional capacity of reinforced components under composite stress. Simulation results showthat the transverse or hoop reinforcement by CFRPs is the main factors in improving thetorsional capacity; concentrated loads in the middle of beam span and the torsional capacityare negatively correlated. The failure modes of finite element model are examined, the stressand strain of steel, concrete, CFRP sheets and the torsional capacity of model components arecalculated, and the analysis of failure mechanism of CFRP-reinforced concrete beams isperformed. The analytical results show that CFRP can sustain tension; in addition, the bindingeffect of CFRP sheets on concrete also is an important factor for improving the torsionalcapacity of components.Based on the variable angle space truss theory for softening concrete modified by Hus,the stress mechanism of CFRP-reinforced RC beams under composite stress of bending, shearand torsion is analyzed, and the whole process of analytical procedure for components under the combined action is worked out. After referencing the formulas of twisted in code fordesign of concrete structures, the computational theories of engineering application arediscussed, and some simplified formulas of torsional capacity for FRP-reinforced concretebeams under composite stress are obtained. Finally, we introduce a case of actual engineeringabout track beams in wharf and carry out the analysis. The results show that the appropriatestructural constraints can improve the torsional capacity of concrete beams effectively.