| Our country has a large number of structure,maintenance and reinforcement is a powerful measures to continue the life of the structure,Conforming to the national sustainable development strategy,compared with other reinforcement methods,External prestressing has great advantages,The paper mainly carries out the theoretical,numerical simulation and experimental analysis,based on the technology of external reinforcement of tilted belly poles and the finite element software ABAQUS,combined with the National Natural Science Foundation of China.(1)By using the geometric equation and balance equation of the external cable and belly poles,the tangential stiffness matrix of the external prestressed cable is derived.The equivalent nodal load of the external prestressed cable end force at the center of the beam end is derived by the static equivalent principle,which can analyse the effect of external prestressed reinforcement beams on the joints.Conclusion: the theoretical formula takes into account many factors and adopts the incremental linearization analysis method,and the theoretical formula is also applicable to nonlinear analysis.(2)Reinforced concrete frame model with three layers and two span built in the laboratory,entity model of the Frame structure is built on the finite element software ABAQUS,the reliability of the laboratory frame model is simulated by ABAQUS software to verify the data of vertical load test.(3)The frame beam strengthened by external prestressing,the frame model is used to analyse the joint of steel and concrete stress in the three different states including the prestressed stage,vertical load and horizontal load,and analyzed the position of plastic hinge.Conclusion:1)The secondary bending moment of the beam caused by prestress is positive bending moment,and it can offset the negative bending moment of the beam end caused by the vertical load,increase the positive bending moment of the beam end caused by the horizontal load,and reduce the seismic performance of the joints;2)under vertical load,Compared to the unreinforced model,The hooping of Joint suffers from less force,which delays the yield of the joint stirrup and increases the ultimate shear strength of the joint.,under horizontal loads,Compared to the unreinforced model,The hooping of Joint suffers from much force,which leads to the early yield of the joint stirrup and the early failure of the joint;3)under vertical load,the internal force of externally prestressed tendons in the elastic stage increases linearly with beam deflection,the internal force of externally prestressed tendons in the plastic stage increases nonlinearly with beam deflection,under horizontal load.The internal force of external prestressing tendons remain unchanged.(4)After the beam is strengthened,The shear capacity of the edge joint is reduced.A new reinforcement technology with external prestressing hoop is put forward to reinforce the joints,and the formula of the shear capacity of the joints is put forward based on the standard. |
PDF Full Text Request