Study On The Deterioration Of Isolation Rubber Bearing Under The Condition Of Large Temperature Difference Circulation

Due to its high altitude,thin air and other factors,the Qinghai-Tibet Plateau region in China,known as the "roof of the world",has formed complex and unique climatic conditions.It’s also one of the largest earthquake areas in China,with strong seismic activity and frequent large earthquakes.In addition,major projects such as Qinghai-Tibet Highway are all constructed in this area,so it is necessary to carry out detailed and in-depth seismic research on it.After years of development,isolation technology has become very mature and has many advantages over traditional seismic design.Therefore,isolation design has become the primary option in many major engineering projects.If the isolation design is adopted on the Qinghai-Tibet Expressway,the isolation components will inevitably be affected by many adverse factors,such as strong ultraviolet light,low temperature,frozen soil and large day-night temperature cycle.This paper is to study the influence of the longterm effect of large diurnal temperature difference on the performance of isolation bearing.First of all,based on the relevant research conducted by scholars at home and abroad,this paper combines the real climatic conditions of the Qinghai-Tibet Plateau in China and the actual working environment of seismic isolation components in the built major engineering projects,according to the relevant test codes and national standards,a test scheme of artificially accelerating large temperature difference cycle action for several common rubber bearing and rubber material was developed under laboratory conditions.The mechanical properties test scheme and specific test conditions for the test bearings and rubber material samples are formulated respectively.On this basis,related experimental studies were carried out from two aspects of bearing and rubber.The analysis of the horizontal equivalent stiffness and equivalent damping ratio of the three bearings shows that the lead rubber bearings have the lowest sensitivity to the large temperature difference cycle,that is,they are more suitable for the working environment with large temperature difference cycle.This point is also supported by the summary of the variation law of its post-yield stiffness and yield force in this paper--whether under 100%shear strain or 250% shear strain,after a complete cycle test process of large temperature difference,its post-yield stiffness only shows a small increase,and its yield force almost has no change.The analysis of the Shore hardness,tensile strength and elongation at break of the four rubber materials showed that the property degradation of natural rubber was more obvious due to the large temperature difference cycling action,while the property degradation of high damping rubber was not too sensitive due to the large temperature difference cycling action.Therefore,high damping rubber is superior to natural rubber only from the rubber level when dealing with the climatic conditions under the long-term effect of large temperature difference cycle.