Research On High Fidelity Numerical Model For High Rise Shear Wall Structures Under Sophisticated Loading Conditions

The mechanical behavior of shear walls has significant influence on the seismic behavior of high-rise structural systems.However,existing numerical models cannot precisely describe the microscopic rule and failure mechanism of the crack development of shear wall structures under complicated loading conditions.Therefore,the existing numerical models cannot accurately predict the performance degradation behavior and failure mode of shear wall structures.In response to this,this dissertation conducts successive research on reinforced concrete shear walls and steel-concrete composite shear walls.The high-fidelity numerical model of shear walls considering reinforcement sliding,shear softening,pinching effect and sliding failure is developed.The crack spacing prediction method is proposed based on fracture mechanics theory,and the force transfer mechanism of shear wall under tension-compression-bending-shear combined load is revealed.The design method of shear wall structure under sophisticated boundary condition is proposed.The major research achievements are as follows:(1)Four reinforced concrete shear walls are tested under combined tension-bending-shear load.Based on strain measurement data,the shear force contribution of horizontal distributed rebar throughout the loading history is recognized.The overestimation of shear contribution of horizontal distributed rebar in Chinese and international design codes are discussed.Based on the novel two-dimensional constitutive model,the test results are simulated and the accuracy of the model is validated.The test database of the reinforced concrete shear wall under combined tension-bending-shear load is developed,and the simplified design formula for tension-shear capacity is proposed.(2)Based on the basic assumption of fixed crack model,the two-dimensional concrete constitutive model of multi-layer shell element and three-dimensional concrete constitutive model of solid element are developed for ABAQUS implicit solver,respectively.The following five key features of concrete are accurately simulated,including the compressive softening of unconfined and confined concrete,tension softening,pinching effect,strength degradation due to principal tensile strain and shear softening.The method to reduce mesh sensitivity is validated.Three key problems are investigated,including the sliding failure,the dowel effect of longitudinal reinforcement anchorage slip of longitudinal reinforcement.(3)Based on a large amount of finite element simulation,the accuracy of developed two-dimensional and three-dimensional constitutive model for simulating the shear wall structures with various parameters validated respectively.The significant influence of stud slip effect on the simulation result of composite shear walls is discussed.The modeling scheme to simulate the anchorage failure mode of the composite shear wall under combined tension-bending-shear load based on fiber beam-column element is proposed.The recommendations for anchorage design are proposed.(4)The average crack spacing prediction model is proposed based on fracture energy criterion.Based on the fundamental theory of fracture mechanics,the influence of concrete strength and size effect on the average crack spacing is investigated.Besides,a database of 136 test data of tensile or flexural specimens and a database of 42 shear wall specimens are developed for the average crack spacing of reinforced concrete members.The simplified design formula for average crack spacing is proposed considering size effect and concrete strength variation.The simplified design formula has high accuracy and can be easily calculated.The progress of the concrete model is achieved from simulating cracking strain to simulating the crack width.The proposed subroutine package for simulating shear wall structures has included the dominant mechanical behaviors in whole-process of concrete and can be adopted for high-fidelity whole-process simulation of shear wall structures.The subroutine package provides a kernel tool and reference for the performance-based design of sophisticated structural systems.