Earthquake Damage And Seismic Performance Analysis Of Base Isolated Building Structure

At present,the isolation technology has been widely used in the building structure,and has been tested in the actual earthquake disaster,and has achieved good damping effect.With the deepening of research,isolation technology has developed into the field of high-rise buildings.Under the earthquake action,the structure damage of base isolated building is worth further study.The main research contents and achievements of this paper are as follows:(1)In this paper,a frame shear wall structure in an 8-degree(0.2g)area is selected as the practical project.First,the ETABS finite element software is used to analyze the isolation design of the structure.The rubber isolator element and gap element are used to simulate the parallel operation of the isolation support,which is used to consider the different tension and compression stiffness of the support.Secondly,the reaction force at the bottom of the column under the condition of the representative value of gravity load(D + 0.5L)is extracted,and the primary layout of the isolation layer is carried out.Thirdly,seven seismic waves which meet the requirements of time history analysis are selected from the seismic wave library,and input to ETABS software to design and analyze the frame shear wall seismic structure and the isolation structure.Through calculation,the damping coefficient is 0.38 less than 0.4,and the superstructure can be reduced by 1 degree design.Finally,the checking calculation analysis of the frame shear wall isolation structure under the rare earthquake action is carried out.The results show that the calculation results of the relevant parameters of the isolation support meet the requirements of the code.The first period of the isolation model is about 400% of the seismic model,and the damping ratio reaches 60%.The damping performance of the isolation structure is significant.(2)Using structural design software,the reinforcement design and analysis are carried out,and the reinforcement of frame shear wall seismic structure and isolation structure are obtained.In the design and analysis of the frame shear wall isolation structure,the value of β(horizontal damping coefficient is 0.38)/ ψ(adjustment coefficient,0.75)is input into the calculation parameters of the superstructure as 0.507,and the reinforcement information of the isolation structure is obtained according to the design and analysis of 1 degree reduction of the second seismic measure in article 12.2.7 of the code for seismic design of buildings.When the frame shear wall seismic structure is designed and analyzed,the seismic parameters are input according to the original seismic intensity,and the reinforcement information of the seismic structure is obtained.(3)According to the design parameters and reinforcement information,and considering the nonlinear mechanical behavior of materials,the finite element software ABAQUS was used to establish the seismic structure model of frame shear wall and the isolation structure model(CDP model for concrete,double fold line model for reinforcement and connector elements for isolation support).The elastic-plastic time history analysis of the two structures was carried out.Based on the analysis of dynamic elastoplastic time history of isolated structure and aseismic structure in 8 degree(0.2g)area,the natural seismic wave Taft wave and El Centro wave are selected,and the adjusted seismic wave amplitude is 200 Gal.the conclusions are as follows: 1)The aseismic structure has entered into plastic deformation while the isolated structure remains elastic;2)The column end and beam end of the aseismic structure occur Plastic damage,the isolation structure appears very slight damage,the maximum damage value is only 30% of the seismic structure;3)The shear wall damage of the seismic structure is concentrated in the edge of the wall limb,the corner of the wall,the hidden beam in the wall,but the shear wall of the isolation structure has no obvious damage.(4)By using ABAQUS software,the seismic wave Taft wave and El Centro wave are selected,and the adjusted seismic wave with an amplitude of 400 gal is input.The dynamic elastoplastic time history of the isolated structure and the seismic structure under the rare earthquake in the area of 8 degrees(0.2g)is analyzed respectively.Through the comparative analysis of the structural damage map at 5S,15 s and 20 s,the following conclusions are drawn: 1)The damage mode of the column and the structure of the seismic structure The damage of column first appears in the side column of low floor,then extends to the corner column and middle column,and develops from low floor to high floor.The damage of column of isolation structure is very slight,first occurs in the middle column where the front and rear facades of the bottom floor of the structure are located,then extends to the columns on both sides of the structure and along the column height direction;2)The damage mode of beam,the damage of seismic structure beam first appears At the beam end of the outer edge beam of the low floor of the structure,and then from the beam end to the middle of the beam to extend the whole beam.At the same time,the damage extends from the outer edge beam of the structure to the beam of the middle of the structure,from the low floor to the high floor.In the isolated structure,the damage of the beam is mainly concentrated in the bottom and top of the structure;3)The damage mode of the shear wall,the damage of the shear wall of the isolated structure is small,and the shear wall of the seismic structure is small.The damage mode of the shear wall at the edge of the structure is as follows: first,the corner of the shear wall at the bottom floor appears damage,then the damage accumulates and extends upward along the outer edge of the wall limb and 45 degrees in the plane,and finally the damage mainly extends to the fifth floor,no obvious damage is found at the 6th-12 th floor,while the damage of the intermediate wall is relatively light,mainly distributed at the corner and edge of the wall limb at the 1st-3rd floor.