Research On Influence Characteristics Of Ground Cracks On Seismic Performance Of RC Frame Structures

Ground fissures run through most of Xi’an urban area,The urban underground pipe gallery,road and building was destroyed greatly by the ground crack.The current norms usually take the way of avoiding for the engineering construction in the area affected by the ground fissures,which results in a great waste of resources,and also seriously restricts the land use and urban construction development of Xi’an city.Xi’an is in the area of high earthquake incidence,and the strong earthquake action can not be ignored.Therefore,the study of the internal force variation and deformation law of the structure under the double action of ground fracture and earthquake in the standard avoidance distance can provide the basis for the engineering construction in the area affected by ground fracture.An actual frame structure is taken as the research object,and a finite element model of near f₆ground fissure site superstructure is established for analysis.The main research contents and conclusions are as follows:（1）Three kinds of seismic waves are input to study the structural displacement and internal force variation under the influence of different avoidance distance,ground motion type and peak acceleration factors.The results show that the structural damage of the hanging wall site is far greater than that of the footwall site;（2）The variation of the maximum inter story displacement angle of the structure under the most unfavorable working condition is analyzed.The error of horizontal maximum seismic influence coefficient under different avoidance distance is studied by referring to the seismic design code.According to the analysis results,the adjustment formula of the maximum horizontal influence coefficient of the upper structure of the ground fissure site is established;（3）Referring to the prediction of 50 year settlement of ground fissures,the settlement of the site in 10,30 and 50 years is simulated by applying load.The floor displacement before and after settlement is analyzed.The results show that the footwall site is weakly affected by the settlement,while the upper floor displacement increases with the service life,and the annual displacement increases year by year;（4）The internal force and displacement of the structure under the double action of strong earthquake and uneven settlement are analyzed.The results show that the existence of uneven settlement of ground fissures further intensifies the lateral displacement of the structure and further weakens the seismic performance of the site structure of the hanging wall.