Study On Seismic Behavior Of Prestressed Self-resetting Masonry Wall Based On Finite Element Simulation

With the development of society,the aseismic design concept of the structure,which only considers from the safety level,is gradually difficult to satisfy people’s expectations for urban development.The concept of "Resilient City" has gradually transformed the traditional "Earthquake-Resistant" stage of "Small earthquakes can not cause structural damage,moderate earthquakes can ensure the buildings can be repaired,and large earthquakes can not cause structure collapse" into the "Earthquake-Tolerance" stage which focuses on process orientation and improves the "toughness" of urban system.According to the previous earthquake disaster data,the cost of repairing the building is much higher than the structural cost of the building itself.From the perspective of engineering,in order to make the structure have a good recoverability,improving the self-resetting performance of structures becomes the focus of seismic design.At present,most of the researches on the self-resetting performance of structures focus on concrete structures and steel structures.However,there are still a large number of people living in towns and villages which dominated by masonry structures.In addition,local residents due to traditional thinking,economic conditions and other factors lack of awareness of earthquake fortification.In this instance,a cost effective method to improve the self-retaining performance of masonry structures is urgently needed.Based on the practice of self restoring concrete structure and steel structure,combined with the properties of masonry structure,the pre-stressed steel strand technology in masonry wall structural column is proposed.The main conclusions are as follows:(1)Through a large number of studies on self-resetting concrete structures,the main factors affecting the self-resetting performance of concrete structures are summarized as follows: the magnitude of initial prestress,the size of wall and friction damping material.It provides a reference for exploring the factors affecting the self-resetting performance of masonry structure.(2)Based on the test data of self-restoring concrete shear wall and common masonry wall,the finite element contrast model is established.On this basis,referring to the factors that affect the self restoring performance of concrete,combining with the properties of masonry structure and the results of finite element analysis,the factors influencing the self-resetting performance of the masonry structure are proposed,including the initial prestress,the height-to-width ratio,the upper load and the setting of the damping filling layer.(3)The ABAQUS software was used to establish a finite element model with 5ordinary masonry walls with constructional columns and 14 self-resetting masonry walls.By changing the prestressing force,the ratio of height to width,the load on the upper part of the wall and increasing the damping layer,the factors affecting the seismic performance of the self-resetting masonry wall were explored.By extracting the experimental results,we found that: The prestressed steel strand can effectively improve the stress distribution inside the masonry structure wall.The structure has been changed from one in which the force is concentrated at the bottom of the wall column,which is very easy to be crushed at the bottom of the column,to one in which the force is greater at the upper and lower ends and less at the middle.The stress distribution becomes more reasonable.At the same time,the stress of the structure can be reduced and transferred from the wall to the constructional column.The incorporation of prestressed strands can significantly improve the structural stiffness,and this effect is independent of the size of the prestress applied but relates to the number of prestressed steel strand configurations.At the same time,the greater the applied initial prestressing,the better the wall’s self-reset performance and energy-consuming capacity.However,the energy consumption capacity is lower than before the prestress is added.The greater the wall aspect ratio,the less structural stiffness,the weaker the self-retaining capacity and the higher the energy consumption capacity.The higher the upper load,the greater the wall stiffness,the better the self-retaining performance and the lower the energy consumption capacity.The addition of the damping filling layer will increase the rigidity of the wall,reduce the self-reset performance,and enhance the energy dissipation capacity.From the view of self-reset performance,the initial prestress increases by 2 times,and the residual deformation of the structure decreases about 11.22%.The height width ratio increases by 2 times,and the residual deformation of the structure increases about 200%.The upper load increases by 2 times,and the residual deformation of the structure decreases about 77.24%.The residual deformation of the structure increased by about 110.77% with the addition of damping filler layer.(4)Based on the results of finite element analysis,the influence of prestress,aspect ratio and upper load size on the relative residual deformation and energy dissipation coefficient of the wall is analyzed,and the calculation of the law of change is obtained.(5)On the basis of the previous research,regression analysis was used to establish a formula for calculating the limit bearing capacity of self-resettling masonry walls with structural columns.Based on the analysis of numerical simulation results,the rationality of bearing capacity calculation formula is verified.