Analysis Of Collision Response Of Large Chassis Isolation Structure In Extremely Rare Earthquake

Earthquake is a sudden natural disaster with great randomness and high uncertainty.After the earthquake,the actual seismic intensity of the meizoseismal area and its surrounding areas is often much greater than the fortification intensity,and some seismic joint between the buildings is too narrow to avoid collisions caused by earthquakes,despite the usage of seismic isolation technology,which results in great economic losses and casualties.Therefore,it is essential to analyze the collision of the isolated structure in the case of extremely rare earthquakes,i.e.great earthquakes.Aided by SAP2000 finite element analysis software as the calculation tool,this paper mainly includes four parts of research:First of all,literature of collision problems at home and abroad was reviewed,which introduced the main contents of structural collision research.Based on this,the necessity of research on the collision response of large chassis isolation structures in large earthquakes was illustrated.Secondly,the peak acceleration of large earthquake under different intensities was obtained by interpolation method.Four methods for ground motion amplitude modulation and two analysis methods for collision theory—coefficient of restitution and contact element method—were introduced.Detailed description and comparison were given to the latter two methods.Next,based on the above theory,the finite element model used for collision analysis was established.Firstly,the structure was equipped with isolation design to meet the requirements of isolation.Then,plastic hinges were installed on the qualified seismic isolation model to simulate the nonlinearity of the material and the contact elements were set to simulate the pounding element.Finally,three cases were investigated based on the established finite element model,including whether to consider collisions in great earthquakes or not and considering collisions in rare earthquakes.Through comparative analyses of collision force,acceleration and displacement,the research shows that there is no direct relation between peak collision force and peak acceleration of ground motion,but the maximum relative displacement difference between adjacent structures is a key factor of peak collision force;and amplification effects of acceleration only occur in the collision layer,barely influencing the acceleration peaks of other floors;in addition,the impact of the collision on the positive peak displacement response of left-right structures is reversed,while the negative peak displacement response is amplified.In general,flexible structures in the collision direction are more subject to collisions.