Multi-story Concrete Isolation Structure Under Horizontal And Vertical Seismic Coupling

Base-isolation technology is a technology to attenuate earthquake effects by introducing a flexible layer between the foundation and the superstructure.Compared with traditional anti-seismic theory,it has better economics and safety.Therefore,since the idea of base isolation was proposed,its related theory has developed rapidly.The previous view was that the damage to the structure caused by earthquakes was mainly caused by horizontal earthquakes.In China's "Code for Seismic Design of Buildings",only vertical earthquakes are considered for high-rise or long-arm and large-span structures in individual high-intensity areas.Affected by this view,the current domestic research on base isolation is still mainly focused on horizontal isolation.Based on the current status of the base-isolation technology and its shortcomings,the paper proposes to study the necessity of a low-cost basic seismic isolation device.Based on the knowledge of basic seismic isolation theory,a new three-dimensional spring isolation pier parameter design method is proposed.Taking into account that the spring isolation unit is the core force component of the device,the horizontal and vertical stiffness of the spring isolation device is given.The relationship between the design parameters of the spring and the related structural requirements of the new three-dimensional seismic isolation pier.In order to verify the reliability of the three-dimensional spring-isolated pier design theory,a shaking table simulation seismic test was conducted.The acceleration peaks of the rigid block table and the shaking table top were collected and analyzed using a vibration pickup.The experimental analysis shows that the design parameters of the three-dimensional spring isolated pier are reliable.Considering that three-dimensional seismic isolation devices are mainly used in low-rise buildings in the villages and towns,such buildings are not within the range of vertical earthquakes for which resistance is specified.An incremental dynamic analysis of a three-story reinforced concrete frame with OpenSees shows that the vertical earthquake action cannot be ignored.After modeling the above-mentioned frame,the seismic isolation device was modeled,and the internal forces under multiple ground motions were analyzed.The results show that under the actual earthquake,the new three-dimensional seismic isolation device meets the design requirements,and its shock absorption effect is excellent.With vertical seismic components,its shock absorption is better.After setting up a three-dimensional seismic isolation device,the column shear force of the frame structure is significantly reduced;the bending moment of the beam support cross-section is significantly reduced;the internal force generated by the frame under horizontal and vertical earthquakes reaches or even lower than that of the non-isolation frame.Under the action of earthquakes,internal forces under horizontal and vertical earthquakes,that is,after the installation of three-dimensional seismic isolation devices,the design of low-rise residential buildings does not consider the role of vertical earthquakes to be partial to safety.