Uncertainty Analysis Of Base Isolation Structure Parameters Of Foundation Using Laminated Rubber Bearing

As the most widely used isolation design,laminated rubber bearing plays an important role in improving the seismic performance of the structure.Therefore,the uncertainty of the mechanical property parameters of rubber isolation bearing will affect the seismic performance of the structure.Taking the base-isolated structure as the research object,this paper analyzes the probability distribution and statistical parameters of the horizontal and vertical mechanical property parameters of the laminated rubber bearing through probability statistical method,and analyzes the influence of the statistical parameters of the laminated rubber bearing on the seismic performance of the base isolated structure.The main research contents of this paper are as follows:(1)This paper first introduces the method of obtaining the mechanical property parameters of rubber bearing.Through the basic mechanical property test,the mechanical properties of natural rubber bearing and lead rubber bearing are tested and the horizontal mechanical properties of rubber bearing under different shear strains are also tested.According to the result,the horizontal equivalent stiffness of natural rubber bearing and the post yield stiffness of lead rubber bearing decrease with the increase of shear strain while the lead rubber bearing increases with the increase of shear strain.(2)In order to study the uncertainty of mechanical characteristic parameters of rubber bearing,30 groups of horizontal and vertical mechanical property parameter test data of natural rubber bearing and lead rubber bearing are obtained through repeated cyclic loading test,and the obtained test data are statistically analyzed.The results show that the probability distribution of rubber bearing with test uncertainty obeys normal distribution and the CV is relatively low.(3)The collected test data of rubber bearing are sorted out by the classification method of aleatory uncertainty and epistemic uncertainty.Then the probability distribution of the data is fitted by statistical method,and the fitted probability distribution is verified by K-S test.Finally,the statistical parameter analysis of mechanical parameters is carried out.The results show that under the grouping of aleatory uncertainty,the horizontal mechanical property parameters of rubber bearing basically obey the normal distribution and the vertical mechanical property parameters obey the lognormal distribution.While under the grouping of epistemic uncertainty,the horizontal mechanical property parameters of rubber bearing basically obey the extreme type-I distribution,and the vertical mechanical property parameters obey the extreme type-III distribution.(4)Taking the SDOF of the base-isolation structure as the research object,this paper studies the influence of the change of rubber isolation bearing on the acceleration attenuation ratio and seismic influence coefficient of the isolation structure.A LRB composite isolation structure is established through the Open Sees,and 15 seismic waves are selected to study the influence of the mechanical property parameters of different isolation bearings on the seismic response of the structure,Through IDA analysis,cloud diagram of the relationship between ground motion intensity and seismic demand parameters of superstructure and isolation layer under different bearing mechanical parameters are respectively obtained.And the vulnerability curves of different bearing mechanical parameters are obtained through vulnerability formula.The results show that the bearing yield stress and horizontal stiffness have significant effects on the seismic response of the structure.