Research On Behavior And Failure Of Reinforced Concrete Walls Under Seismic Load

One of design requirements of building structures is to avoid the structural collapsing in order to protect people's life and property safety during strong earthquakes.Even if the extreme cases like structural collapsing is inevitable,it has important significance for broadening the trapped people's survival space and decreasing people's life and property loss and furthermore for post earthquake relief and homeland rebuilding,if some reasonable collapse modes of building can be designed intentionally.The post earthquake damage indicate that the unreasonable failure modes of building structure and main member are main sources which cause casualty and property losses due to strong seismic loading.The vertical walls bearing on seismic loadings are main factors which determine the structural collapse mode,and furthermore resulting in different earthquake hazards.This paper researches collapse mechanics and failure modes of reinforced concrete(RC)walls under seismic loading.In the dissertation,firstly,the Mohr-Coulomb failure criterion with a tension cutoff is formed by linking up Rankine tensile failure criterion and Mohr-Coulomb shear failure criterion reasonably,secondly,the criterion of different kinds of cracks in RC walls are obtained by the Mohr-Coulomb failure criterion with a tension cutoff,finally,the combined model integrating the arch model,macro truss model and discrete element model is used to simulate the RC wall and furthermore form RC wall collapse failure criteria.The concrete crack criterions in RC wall and collapse failure modes of RC walls are validated by the ANSYS software in this dissertation.Based on the crack distribution law of RC wall and discrete element method,the mechanical behavior of cracked RC wall is simulated by the simplified software model and the main factors influencing RC wall collapse are obtained.In order to validate RC wall collapse failure modes and the effect on survival space of collapsed building,a set of scale RC space models with various axial compression ratios,shear span ratios and reinforcement ratios are designed in this dissertation.Pseudo-static experimental research on these models subjected to lateral load is performed and the collapse mechanics of RC wall is obtained and the validity the theoretical analysis is verified.It is the loss of vertical-load-carrying capacity in RC frame-shear walls under horizontal load that leading to cascading vertical collapse of RC building during strong earthquake.For the purpose of forming the necessary survival space in the building impacted under strong earthquake,there must have enough building components carrying vertical load at any time.Therefore,the design method of a new collapse resistant structure named as compression-shear separation structure is proposed,in which the building components carrying vertical load are separated from the building components carrying horizontal load.When the strong earthquake happens,the RC walls bearing both the vertical and horizontal load will failure,but the columns separated from RC frame-shear walls can survive and can carry vertical load and form the survival space.The design concept of the anti-collapse structure has been proved by laboratory test and provide reference for anti-collapse design of structure.