Topology Optimization And Reinforcement Design Of RC Shear Wall Under Low Reversed Cyclic Loading

In recent years,earthquakes have occurred frequently all over the world,and reinforced concrete shear wall,as the main lateral force-resistant components in high-rise structures,are one of the most important seismic defense lines.Reinforced concrete shear wall under current design methods are prone to brittle shear damage with insufficient ductility.Topology optimization has good graphical evolution capability,which can objectively construct a reasonable strut-and-tie model and then guide the design,providing a way out for the design of reinforced concrete shear wall.Therefore,in this paper,proposes the evolutionary structural optimization algorithm based on the low reversed cyclic loading,and on this basis,the reinforcement design of reinforced concrete shear wall is conducted.The simulation verification of the corresponding components is completed,and the influence of design parameters on optimization are discussed.The main contents include:Firstly,the optimization mathematical model based on linear elastic analysis and the optimization mathematical model based on material nonlinear analysis are established respectively,and the evolutionary structural optimization method of reinforced concrete shear wall under low reversed cyclic loading based on finite element analysis of reinforced concrete integrated elements model is proposed.Among them,the optimization method based on the linear elastic analysis constructs the optimization sensitivity according to the strain energy to maximize the structural stiffness under the set volume constraint,with the status of elements as the design variable.The optimization method based on material nonlinear analysis constructs the optimization sensitivity according to the element plastic strain energy to maximize the structural energy dissipation under the set stress constraint with the status of elements as the design variable.Four optimization cases of reinforced concrete shear wall based on linear elastic analysis with unidirectional loading and repeated loading and nonlinear analysis with unidirectional loading and repeated loading respectively.Comparison of four optimization cases of reinforced concrete shear wall based on linear elastic analysis and nonlinear analysis with unidirectional loading and repeated loading respectively.The results show that: The topology results under repeated loading have a higher level of optimization than the symmetric envelope topology results under unidirectional loading and are more suitable to guide the design;the optimization level of topological results based on material nonlinear analysis is higher than that of topological results based on linear elastic analysis;the evolutionary structural optimization algorithm for reinforced concrete shear wall under repeated loads based on nonlinear analysis can consider the material nonlinear properties exhibited by concrete beyond the elastic phase,and which can effectively improve the energy dissipation capacity of reinforced concrete shear wall.Secondly,the topological results obtained from the evolutionary structural optimization algorithm of reinforced concrete shear wall under repeated loads based on nonlinear analysis guide the establishment of the strut and tie model,followed by the completion of the reinforcement design,effectively integrating the topological optimization method into the engineering design,forming a seismic design method for reinforced concrete shear wall based on topological optimization&strut-and-tie model.Non-linear finite element verification and simulation analysis of reinforced concrete shear wall confirm the advantages of the new method of optimal design.The results show that: on the one hand,the optimized reinforcement shear wall has higher utilization rate of reinforcement under low reversed cyclic loading,larger bearing capacity,better energy dissipation capacity;on the other hand,the reasonable setting of distributed reinforcement in the optimized reinforcement shear wall increases the structural steel consumption slightly,but improves the structural ductility to a certain extent under the premise of ensuring the structural bearing capacity.Finally,by comparing the optimized calculations of reinforced concrete shear wall with different aspect ratios and different axial compression ratios under low reversed cyclic loading.On the one hand,the generality and stability of the evolutionary structural optimization algorithm for reinforced concrete shear wall under low reversed cyclic loading are verified;on the other hand,the effects of different design parameters on the optimization results of shear wall under low reversed cyclic loading are discussed and associated design recommendations are given.The results show that: with the increase of aspect ratios,the vertical members on both sides of the optimal topology gradually behave as the thicker variable cross-section members in the lower part,and the number of diagonal members in the mid span area decreases.Continuous spiral stirrups or composite spiral stirrups can be added within 1/2 height along the wall in the areas on both sides of the shear wall for reinforcement;With the increase of axial compression ratio of shear wall,the material importance of both sides of the topology is higher,the inclination angle of the evolved vertical members to the middle decreases,and the number of inclined members in the mid span area decreases.It is suggested to add closed stirrups or continuous spiral stirrups along the wall height at both sides of the wall to increase the strength;Diagonal reinforcement shall be added in the 1/5～4/5 area of the wall to prevent shear failure.In general,the paper proposes an evolutionary structural optimization algorithm for reinforced concrete shear wall under low reversed cyclic loading considering the material nonlinear characteristics of reinforced concrete,which can effectively assist in the establishing a strut-and-tie model to reflect the force transmission path of the structure and ultimately guide the reinforcement design.This new method designs shear wall with better energy dissipation capacity and less prone to brittle damage.This is a pioneering attempt to rationalize the seismic design method of reinforced concrete shear wall and to improve their seismic ductility and energy dissipation performance,which has greater scientific significance and engineering value.