Comparative Study On The Collapse Criteria Of RC Shear Wall Structures Based On Component Deformation

Structures have the risk of collapse in earthquakes,which threatens the safety of human life and property.A variety of seismic collapse criteria have been proposed in domestic and foreign codes and literatures,and reasonable evaluation methods have been obtained in the study of RC frame structures.However,the applicability,rationality and strict control degree of these criteria in RC shear wall structures still need to be studied.In order to accurately evaluate the seismic performance and collapse resistance of RC shear wall structure,it is of great significance to determine a criterion which can reflect the collapse state of the structure.To this end,in this paper,four typical collapse criteria（the elastoplasticity inter-story drift ratio criterion,the first vertical component failure criterion,the material strain criterion and the side-sway collapse mechanism criterion）are selected from three levels of material,component and structure.Because the limit value of component deformation can reflect the real performance state of the component,this paper proposes to apply the component deformation to the research of the actual performance state of the component under each criterion.In this paper,23 typical RC shear wall structures with different fortification intensity,structure height,site period and code age are designed,and the IDA collapse fragility assessment method is adopted.The collapse probability of the structure under each criterion,the actual performance state of the component under each criterion,and the influencing factors of the CMR under each criterion are analyzed.The main works and conclusions are as follows:（1）The critical collapse state of RC shear wall structure is defined according to the seismic damage characteristics of the shear wall structures in the tests and previous large earthquakes,so as to evaluate the rationality of the collapse state under each criterion,and the process of assessing the collapse fragility based on IDA is established.（2）The Code of Design for collapse Resistance of Building structures（CECS 392/2014）^[1]adopts the elastoplasticity inter-story drift ratio criterion and the material strain criterion to determine the collapse of structures.In this paper,a preliminary comparative study of the two criteria,the results show that the strict degree of control between the two criteria,further comparative analysis of the two criteria needs to be carried out.（3）Under the first vertical component failure criterion,the performance level distribution of the first layer shear walls of the model is statistically analyzed.It is found that,except for the failure of the first vertical component,on average,9%of the shear walls are in a state of serious damage.on average,18%of the shear walls are in a state of limited serious damage,almost all shear walls are minor damage or above,which is consistent with the distribution of shear walls damage in real earthquake damage,which indicates that this criterion reflects the critical collapse state of the structures.（4）According to the cumulative collapse probability curve,the fitting effect,the logarithmic standard deviation（discreteness）,the strict control degree and the collapse probability under each criterion are studied.The elastoplasticity inter-story drift ratio criterion,the material strain criterion and the side-sway collapse mechanism criterion are analyzed based on limit value of component deformation.It is found that the elastoplasticity inter-story drift ratio criterion is too strict and the structure is basically in elastic state.the material strain criterion and the side-sway collapse mechanism criterion determine that the control is too loose and the structure is far beyond the collapse state,so all of the three criteria can not reflect the critical collapse state of the structure well.Based on the above,the first vertical component failure criterion can reasonably distinguish the critical collapse state of RC shear wall structures,and has proper strict control degree.Therefore,it is suggested that this criterion be used as the criterion for the collapse fragility assessment of RC shear wall structures.