Experiment, Simulation And Analysis On New Type Of Seismic Isolation System

With the frequent earthquake disasters and development of building technology in recent years, people have much more higher demands on seismic technology. As an effective and economic way of vibration reduction, seismic isolation is more and more highly praised by engineers. Although it has various advantages, applicability and economy remains major obstacles to promoting the use of it. Therefore, many scholars are working to make improvements to the existing isolation techniques or develop new ones. In this paper, new type of isolation devices and seismic isolation technology were taken as research goals. Shaking table tests and theoretical studies on the new base isolation method including two isolation devices were taken.Studies show that when ground motion spread from bottom to top of the ground, the soft soil filter most of the high-frequency ground motion, leaving only low frequency components, and peak acceleration are decreased. From the soil - structure interaction, soft soil - hinged pile isolation method was proposed by project team. To achieve the effect of isolation, two low stiffness points are set on pile. Between low stiffness points, it is filled with soft soil with low dynamic shear modulus. To verify the isolation performance of the method, by using Cyclic Simple Shear System, a small shaking table was developed. Taken layered sponges as model of soft soil, shaking table tests and contrast tests to the sponge soil - hinged pile - Structure were taken. The results showed that the device can effectively reduce the seismic response of upper structure. To get constitutive relationship of the sponge soil - hinged pile system, by using the cyclic loading device of Cyclic Simple Shear System, low cyclic shear tests were taken to the sponge model soil - hinged pile system, and hysteresis curves and skeleton curves were obtained. On this basis, by using computer program of time history analysis method, structures using of the isolation system and the ones not using the system were calculated and analyzed. The calculating results agree well with the experimental results.Through tests and calculations, isolation performances of soft soil - hinged pile isolation system have been verified, but there are still some problems in practical engineering to be resolved. In our country, there are large amount and wide areas of rural residential, and they have higher economic requirements to seismic isolation devices. According to this, project team proposed steel - asphalt isolation layer, a new type of isolation device. The isolation system consists of steel, asphalt, brick, concrete and other common building material composition. By using of the high capacity, low levels shear stiffness characteristics of vertical steel to achieve isolation. In the use of brick piers placed between reinforced, to ensure the safety after the steel yields in the case of revere earthquake occurs. In order to study the isolation performance of the isolation layer, shaking table tests were carried out under different conditions. The results show that the isolation layer has good isolation performance. Ground motion can be significantly reduce when passing to upper structure. The displacement of the isolation layer is relatively small in vibration. The stability and security reserves are good under strong earthquakes; it can still maintain good isolation performance and not collapse in seismic excitation far more than the design intensity.To remedy defects of tests in laboratory, study more situations which are difficult to achieve in it, such as large-scale or full scale dynamic testing, a non-linear finite element model of steel - asphalt isolation layer was established using finite element software MSC.MARC. Using of steel non-linear subroutine UBEAM and spring nonlinear subroutine USPRNG, the Non-linearity of steel and the nonlinear interaction between brick pier and upper beam were respectively simulated. The temperature factor of asphalt ointment was also proposed. To verify the model, modes of specimens in shaking table tests were calculated; all conditions in the shaking table tests were simulated by 3D Finite Element time history analysis. Compared the results with the experimental results, calculated and experimental results show good agreement, verify the accuracy and reasonableness of the model. Finally, the models were set up in finite element models of different heights masonry structure and frame structure; the corresponding isolation layer models under strip foundation and independent foundation were design and build. The dynamic performance and isolation effect of the steel - asphalt isolation layer in different heights of masonry structures and frame structure was simulated, and the results were summarized and analyzed, a series of useful conclusions were drawn.