Research On Seismic Performance And Improved Design Of Precasted Concrete Composite Coupling Beams

The assembled structure has the advantages of fast construction speed,short construction period,energy saving and environmental protection,which meet the policy needs of the sustainable development of China’s construction industry.In recent years,the state has formulated corresponding policies to ensure its popularization and application.The precasted shear wall structure is the main structural form of the high-rise building.As the main energy dissipation component of the precasted shear wall structure,the seismic behavior of the coupling beam is directly related to the seismic behavior of the whole structure.However,there are few studies on the seismic behavior of the precast concrete composite beams.Therefore,it is necessary to study the seismic performance of the precast concrete composite beams.In this paper,the method of finite element numerical simulation is adopted.Firstly,the seismic behavior of the precast concrete coupling beams is studied;Secondly,the parameters affecting the seismic behavior of coupling beams are analyzed,and the influence law of the coupling beam behavior is obtained.Finally,the improvement scheme of the coupling beam reinforcement is put forward,and its seismic behavior is analysed,and the best plan is selected.The main research works is as follows:(1)The finite element software ABAQUS is used to simulate the coupling beam in the test.The finite element analysis model is established through selecting the material constitutive,determining the type of the element and setting the boundary conditions.The validity and correctness of the finite element model are verified by comparing the numerical simulation results with the experimental results.(2)In this paper,combined with the engineering application and the assembly design standard drawing,3 full scale models of the precasted concrete composite coupling beams with different span-to-height ratios are respectively designed.The failure modes,bearing capacity,ductility and energy dissipation capacity of the coupling beams are analyzed using finite element software to simulate the precasted concrete composite coupling beams.The results show that the shear failure of coupling beam with a span-to-height ratio of 1.5 has the highest bearing capacity,but its ductility and energy dissipation capacity are poor;the span-to-height ratio is 2.5 in the bending shear failure mainly by bending failure,the bearing capacity is the lowest,but its ductility and energy dissipation capacity are better;The bending shear failure of coupling beam with a span-to-height ratio of 2.0 has higher bearing capacity and better ductility and energy dissipation capacity,and its behavior is the best.(3)Based on the precasted concrete composite coupling beams with a span-to-height ratio of 2,34 models of precasted concrete composite coupling beams considering diffirent parameters are designed and analyzed by using the finite element software.The impact of the span-to-height ratio,the strength of concrete and the reinforcement ratio on the seismic behavior of the precasted concrete composite coupling beams are studied.The results show that the span-to-height ratio has great influence on the behavior of coupling beams;The increase of concrete strength can significantly increase the bearing capacity of coupling beams,while the ductility and deformability of coupling beams are greatly reduced;The influence of the change of reinforcement ratio on the behavior of coupling beams is different.Similarly,longitudinal reinforcement ratio,stirrup ratio and vertical reinforcement ratio have obvious effect on the behavior of coupling beams in a certain range.The research results can provide reference for the design.(4)In order to improve the comprehensive behavior of the precasted concrete composite coupling beams,3 improved reinforcement schemes for precasted concrete composite coupling beams are proposed in this paper;The coupling beams of diagonal reinforcement,rhombus reinforcement and comprehensive reinforcement are designed respectively,then the model is established by the finite element software;Failure modes,bearing capacity and energy dissipation capacity of the common reinforcement,diagonal reinforcement,rhombus reinforcement and comprehensive reinforcement coupling beams are compared and analyzed.The results show that the coupling beams with diagonal reinforcement,rhombus reinforcement and comprehensive reinforcement can effectively improve the bearing capacity,the deformation and energy dissipation capacity of coupling beams;Through the comprehensive analysis of the bearing capacity,ductility and energy dissipation capacity of the coupling beams,it is found that under low cyclic loading,the positive and reverse behavior of the coupling beam with the diagonal reinforcement is more balanced and best.