Study On Equivalent Linearization Method In Design And Application Of Seismic Isolated Structure

After the Wenchuan earthquake,seismic disasters in China continued to occur,causing huge casualties and property losses.Most of these damages are caused by the destruction of the building structure.This has also led to the widespread application of the energy dissipation and isolation technology in the building structure at the current stage.Especially,the isolation technology has undergone the earthquake and proved to be effective.Although seismic isolation technology has been widely used,the research and application of isolation started relatively late in our country.Isolation structure design is not yet mature compared with the United States,Japan and other countries,such as the rationality of the subdivision design model and the discreteness of timecourse calculation results all affect the safety of the isolated structure.Therefore,this paper first summarizes and analyzes the problems existing in the design method of seismic isolation in our country,and proposes the use of overall design method to design the isolated structure.Then we discuss the problems that need to be solved by using the overall design method of the isolation structure.Through the research of these problems,we puts forward improving design method of equivalent linearization for isolated structure to adapt to our country seismic codes,and uses the improved method proposed in this paper to analyze a high-rise shear wall structure with laminated rubber isolation bearing.The results are close to the results of the shaking table test and prove the rationality of this method.The specific research content and conclusions of this article are as follows:(1)Actual engineering examples show that the isolation design method is too dependent on the time-history analysis results,which can lead to reach the expected effect of isolation by selecting the suitable seismic wave.But the way only through replacement seismic waves to achieve the desired effect of isolation,does not improve the safety of the structure,there is a greater potential for dangerousness;and the results of component section and reinforcement that are calculated by the traditional design method is large,but this oversized section and reinforcement does not increase the safety of the structure all the way.(2)Seismic wave duration has a great influence on the seismic response of isolated structures.The result of using dynamic analysis method is still very discrete,when the wave is selected or created only according to code's design response spectrum.On this account,a set of strength envelope parameters to generate artificial wave is given based on ground motion peak acceleration and design earthquake grouping.When the number of artificial waves generated based on the strength envelope parameters in this paper reaches 30,the dispersion of the results can be controlled within 20%,and when the number of artificial waves reaches 70,the dispersion of the results can be controlled within 10%.(3)The calculation result by the method of equivalent linearization based on code's design response spectrum and conventional equivalent parameter is much larger than the dynamic analysis result and experimental result.On this account,a set of equivalent parameter calculation methods was proposed in conjunction with code's design response spectrum for the equivalent linear analysis of the isolation structure.The fitting formulas of the equivalent parameter consider 100 lead rubber bearing models and 100 friction pendulum system models in 9 working conditions.(4)A high-rise shear wall structure with laminated rubber isolation bearing was analyzed by equivalent linearization based on code's design response spectrum and the equivalent parameter proposed in this paper.The results are compared with the experimental results,and show that the method proposed in this paper have higher analysis accuracy and reliability.At the same time,the influences of damping treatment on the results of equivalent linearization analysis are discussed,and damping treatment includes simplified overall damping ratio method,strain energy method,forced decoupling method,and complex vibration method.It show that the seismic response of isolated structures with complex mode method is the largest,and the seismic response with simplified overall damping ratio method is smallest.The strain energy method analysis results are close to the results of the complex vibration analysis.