Numerical Simulation On Earthquake Collapse Process Of RC Frame Structure And Responses Of Its Ruins In Aftershocks

The collapse of houses caused by earthquake disasters has always been an unavoidable problem.The reinforced concrete frame structure is one of the most widely used house building structures in China at present.Its collapse and damage caused by earthquakes caused very serious casualties and economic losses.It is of important theoretical significance and application value to study the collapse mode of typical reinforced concrete frame structure and the response characteristics of ruins under strong aftershocks,learn how to set up rescue channels and their supports,and ensure the safety of rescue,which can provide methods and basis for improving the safety and efficiency of rescue in the earthquake site.Therefore,this paper has carried out relevant research work,as follows:(1)Collected the damage forms of reinforced concrete frame structures in actual earthquake damage,consulted relevant literature at home and abroad,summarized the main collapse forms of reinforced concrete frame structures under earthquake action,and analyzed the damage mechanism of beam and column structures of frame structures.Summarized the current status of theoretical research,experimental research and numerical simulation research on the collapse of reinforced concrete frame structures under earthquake action.The large-scale general finite element analysis software ANSYS/LS-DYNA is determined as the basic method of numerical simulation in this paper.(2)A four-story frame structure was selected as the research object,and the appropriate ground motion input was selected to study the whole process of its damage under the action of earthquake,The solutions to the problems of constitutive relationship between steel bar and concrete,element type,modeling form,material parameter selection failure criterion,dynamic contact algorithm,penetration,etc.in the simulation of strong nonlinear collapse are studied.(3)The numerical simulation analysis of the collapse of the example structure was carried out to discuss and reveal the collapse process and collapse mechanism of the frame structure at different times under the action of earthquake.The internal relationship between the critical time of the collapse of the structure and the ground motion characteristics was studied and analyzed.The safety of the existing human living space,by extracting the interlayer displacement angle of each layer of the frame structure before collapse,the corresponding relationship between the structural damage and the change of the interlayer displacement angle value is analyzed.On the basis of the original reinforced concrete frame structure,non-structural members such as infill walls are established,and the impact of infill walls on the collapse of house buildings is compared and studied from the collapse process,collapse effect,and interlayer displacement angle.(4)Based on the structural analysis of the original reinforced concrete pure frame example,a new analysis model was introduced by filling the wall.From the perspective of the collapse process,the collapse effect,the change of the interlayer displacement angle,etc.The comparative study of the filling wall on the frame structure building collapse Law of influence.(5)The possibility of the flexural bearing capacity of the upper end section of the frame structure that has been destroyed at the bottom end of the column under the combined action of aftershocks and the gravity load of the upper structure is explored to determine the critical PGA of the aftershocks and the corresponding critical tilt angle.(6)Summarized the relevant supporting materials and forms of the rescue and rescue of the earthquake site in China at present,using the restart function of the dynamic explicit analysis software ANSYS/LS-DYNA,the triangle wooden support was established to simulate the rescue channel,and the support structure was set.The method for determining the safety and stability of collapsed ruins under strong aftershocks.