Research On Nonlinear Vibration Characteristics Of The Steel-Asphalt Seismic Isolation Device

The birth of isolation technology has enabled human beings to have more confidence in resisting earthquake disasters and skillfully guarantee the safety of life and property.Although the isolation technology has many advantages,the problem concerning economy and applicability has always been the biggest obs tacle to the large-scale application of the seismic isolation technology.In order to overcome this obstacle,many scholars and experts at home and abroad have invested a lot of energy to develop new seismic isolation devices or to upgrade the existing isolation technologies.In this context,the steel-asphalt seismic isolation technology was conceived,and a series of corresponding shaking table tests simulating real earthquake were carried out successively.The research results show that this isolation technology is able to greatly reduce the acceleration response of the superstructure,and both asphalt and brick piers in the isolation layer can limit or reduce the displacement response of the superstructure.What is also worth noting is that the raw materials used in the isolation technology are some common,inexpensive materials with good durability.In order to perfect the research of this isolation technology,this paper carried out a series of related experiments and theoretical analysis wo rk,aiming to expand the application scope of this isolation technology to the elastoplastic stage.A series of ground motions are input to the designed isolation layer specimen.The seismic simulation test by the shaking table is carried out to study the isolation effect and vibration characteristics of the isolated specimen unde r different working conditions.The test results show that during the test,there is no instability of the isolated steel bar or the overturning of the test piece mod el,and the acceleration reduction coefficient generally decreases with the increase of the input acceleration peak value.Especially when the inputed acceleration is large and the isolated steel bar enters the elastoplastic stage,the acceleration of the isolation layer is signif icantly reduced,and the reduction coefficient of acceleration tends to be 0.3.The simplified model of the isolation layer is firstly obtained.Based on the stress-strain curve of the steel and some calculation assumptions,and considering the P-? effect generated by the vertical load,the skeleton curve of the reinforced asphalt isolation layer is obtained.The skeleton curve is compared with the experimental results,and the two curves agree well.Hence,the skeleton curve model proposed in this paper can provide the basis for the engineering design of the steel-asphalt isolation structure.After determining the hysteresis rule,the restoring force model is established.The resilience model compensates for the lack of research on the resilience model of the steel-asphalt isolation layer.Parametric analysis is carried out to determine the key influence parameters.The statistical analysis software is used to linearly and nonlinearly fit the theoretical analysis results.The practical formula for determining the restoring force model of the isolation technology is given.Using the resilience model proposed in this paper,the elasto-plastic dynamic time-history analysis program is designed.Then the seismic wave used in the test is input,the time history analysis of the test specimens used in the test is carried out,and the numerical analysis results are compared with the test results.The comparison results show that the numerical calculation of the acceleration time history matches well with the experimental acceleration time history graph,and the two peak accelerations occur at a similar time.The time history analysis results are in good agreement with the experimental results,which also proves the theoretical analysis of the restoring force model of the isolation technology is realiable and the vibration table test is effective.Therefore,the resilience model of the reinforced asphalt isolation layer proposed in this paper is proposed can be used in engineering elastoplastic time history analysis.