Mechanism Research On Lateral Force Transmission In Composite Frame-RC Core Wall Structure

Frame-core wall structure is widely used in high-rise buildings.In this structure system,the core wall is the main anti-lateral force member in the structural design,which is often considered to bear most of the lareral force directly.However,seismic response is usually raised by the mass of the structure.Since most weight of the structure is located in the frame,a reliable force transfer path is required to ensure that the seismic force is transmitted to the core wall.At present,the lateral performance of frame-core wall structure is fully studied at home and abroad,but most of the researches focused on the over-all performance.The internal force transfer between the frame and the core wall has not received enough attention.In this paper,the mechanism of lateral force transmission in frame-RC core wall structure system is studied,and both universal and professional finite element software is used to conduct the elastic and elastoplastic time history analysis of the existing structure and standard model.The main research work is as follow:(1)The second chapter makes a preliminary study on the mechanism of elastic shear force transfer in an actual structure under earthquake.The parameters are floor arrangement,bottom connection,seismic direction and floor position,etc.The transmission mode of shear force under earthquake is obtained by using universal design software SAP2000.And the results show that the floor shear force transferred from frame to core wall is mainly transmitted by the axial force of the girder and the internal force of the floor.The mechanism of force transfer is less affected by different earthquakes,and the bottom connection mode only has influence on the lower floor.At the same time,with the raising of the floor position,the floor shear force transmitted by the axial force of the floor is gradually borne by the floor shear force.(2)The third chapter studies the mechanism of shear force transfer of standard model under multi-encounter earthquake.The parameters are floor thickness,wall-girder connection,etc.By using the professional design software MSC.Marc,the overall indexes such as self-vibration period,inter-story displacement angle and base shear force are obtained.Meanwhile,both the envelope state of the whole process and the instantaneous state at the moment of the maximum vertex displacement are studied.The analysis results show that the shear force transfer mechanism is greatly influenced by the connection mode between the shear wall and the steel girder.At the same time,the floor shear force transmitted by the axial force of the floor is gradually borne by the floor shear force with the raising of the floor position.The results also show that the stress distribution of the floor is stable and symmetrical.Finally,the shear transfer mode at the bottom and top floor are significantly different from other floors.(3)In the fourth chapter,the mechanism of shear force transfer under rare earthquake is studied.The standard model with layered shell element in the slab is studied.The parameters are slab thickness,shear wall-steel girder connection,etc.Inter-story displacement angle and base shear force under seismic wave are obtained.Meanwhile,the whole process envelope state of floor shear transfer mode and the instantaneous state when plastic hinge appears are studied.The results show that the mechanism of shear force transfer is greatly affected by the thickness of the slab.At the same time,the floor position has less influence on the shear transfer mode and the stress distribution of the slab is approximately symmetrical.Finally,the shear transfer mode at the bottom and top floor are significantly different from other floors.