Shaking Table Experimental Research On Steel Isolation Pier In Frame And Dynamic Time History Analysis

The basic isolation technology that emerged in the 1960 s transformed the structural seismic design from the traditional “ hard resistance ” to “ soft resistance”.Through a large number of experimental research and engineerin g practice by domestic and foreign scholars,especially the superior performance of the base isolation building in actual strong earthquakes,the base isolation has been proved to be a more efficient and safer technology than the traditional earthquake res istance.The research of base isolation technology has also become a research hotspot in the field of structural earthquake resistance,but the common base isolation technology is relatively expensive.China has a vast territory,and the area in the earthqu ake zone is close to 80% of the country's land area.China's earthquakes have a wide distribution range,shallow focal depth,high frequency of activity,and high damage intensity.At the same time,China is also a big country with unbalanced development.T he vast areas of villages and towns are relatively backward in economy.People are not aware of earthquake resistance.Housing design and construction have not considered sufficient seismic measures,resulting in huge loss of personnel and property during the earthquake.In view of this situation,our research group proposed a steel-asphalt isolation technology with good isolation effect,low cost and simple construction,which is suitable for low-rise masonry structure.And this technology is very suitable f or popularization and application in rural areas of China.In order to further improve the structural system applicable to the steel-asphalt isolation technology,this paper proposes a new steel isolation pier suitable for the frame structure based on the steel-asphalt isolation pier.The calculation model and basic assumptions of steel isolation piers are put forward.The steel isolation piers are simplified to the upper end and can only be horizontally slid beam to be analyzed.The design calculation method of steel isolation piers is introduced in detail.In order to verify the applicability and isolation effect of steel isolation piers for multi-story frame structures,the seismic isolation table test of steel isolation piers was designed.The results show that the steel piers have sufficient elastic restoring force.Under the 6-degree and 7-degree basic intensity earthquakes,the isolation layer is well reset,and the upper frame has no obvious deformation and failure characteristics.The acceleration attenuation coefficient of the isolation layer is about 0.25-0.50,and the maximum acceleration attenuation coefficient of the upper frame is less than 0.7.Under the earthquake,the deformation of the system is mainly concentrated on the isolation layer.The deformation of the isolation layer reaches the deformation of the upper frame more than 5 times.The isolation layer effectively blocks the seismic energy from transmitting to the upper frame,and under the 7-degree basic intensity earthquake,the isolation layer and the upper frame can maintain the elastic phase;the largest interlaminar shear force of the system occurs in the isolation layer,and the shear force between the upper structural layers is kept at a small level.The comprehensive test results show that the steel isolation pier is suitable for the frame structure,and the isolation layer composed of the steel isolation pier has a good isolation effect.The steel isolation pier frame model is simplified into an inter-layer shear model with three mass points.Considering the nonlinearity of the isolated vertical reinforcement,the Wilson-? method is used as the numerical calculation method for stepwise integration,and the nonlinearity dynamic time history analysis is programmed by MATLAB.The numerical calculation results are compared with the experimental results,and the seismic response of the non-isolated frame and the isolated frame under multi-case conditions are analyzed.The results show that the numerical results agree well with the experimental results.It is feasible to simulate the actual structural seismic response by numerical calculation method.The acceleration response of the isolated frame under earthquake action is greatly reduced compared with the non-isolated frame.The setting of isolation layer has a significant effect on reducing the seismic acceleration response of the upper frame.