Strength Research For The Mechanical Properties Of The Rubber Isolation Bearings

Ordinary rubber isolation bearings and lead rubber isolation bearings are the two main forms ofisolation in the isolated building structure, they are the relatively mature technologies at present and have ahistory of20years. In recent years, they have been widely applied to building structures. However, with theincreasing of engineering practices and scientific experiments, they make a better isolation effect, but at thesame time they also exposed some shortcomings: the application of rubber materials in the ordinary rubberisolation bearings lead to low level stiffness and damp, with high level shear deformation in earthquakes. Inlead rubber isolation bearings, the increase of lead core provides a greater damp, but the bearings havelower self-recovery capabilities and bigger initial level stiffness, which is9times larger than the sharestiffness of the rubber bearings after the lead core yield is winded, so they have bad filtering effect on thehigh frequent waves. The tensile of the both bearings is depended on the combination of rubber and steel,and the stretching resistance is not very high, this is a poor part under the strong unknown reverse force inearthquakes, especially under the vertical seismic force during the severe earthquakes, which makes theisolation layer often appear lift-off phenomenon.In this paper the rubber isolation bearings with reinforced components are presented in order tomake up for the disadvantages of the ordinary rubber isolation bearings and the lead rubber isolationbearings. The reinforced components can improve the bearings’ resilience and energy consumption effect,and it also can be the alternative line of defence which improves the safety and reliability of the bearings.This paper makes research on the mechanical properties of the reinforced rubber isolation bearings by usingthe finite element simulation and model tests. The researches and achievements in this paper are listed asbelow:(1) Making a summary of the current related research on the isolation structures and thecalculation theories which effect the basic mechanical properties of the rubber bearings at home and abroad.Pointing out the drawbacks of the rubber isolation bearings, and present a new kind of rubber isolationbearings, the reinforced rubber isolation bearings.(2) Making mechanical properties analysis on the vertical stiffness of the reinforced rubberisolation bearings based on small and big deformation. The vertical stiffness of the two reinforced rubberisolation bearings with inserted steels and the ordinary rubber isolation bearings are basically the same, when they only suffered at the level load. With the increasing of the level shear deformation, the bearings’vertical stiffness decreased due to the effect of the steels. With the increasing of the steels’ diameter, thevertical stiffness shows a decreasing trend, but it is so little to the total decrease range of the ordinaryrubber isolation bearings that can be ignored.(3) The level stiffness of the ordinary rubber isolation bearings and reinforced rubber isolationbearings based on small deformation decreases with the increasing of the vertical load when they bothunder the joint function of the vertical load and level share. The ordinary rubber isolation bearings’ levelstiffness shows a decreasing trend with the increasing of the level share deformation. With the increasing ofthe level shear deformation, the level stiffness of the reinforced rubber isolation bearings based on smalldeformation increases at the beginning of the deformation, but it shows a decrease trend when the levelshare deformation is increasing, due to the effect of the steels.(4) The level stiffness of the ordinary rubber isolation bearings and the reinforced rubber isolationbearings based on big deformation decreases with the increasing of the vertical load when they both underthe joint function of vertical load and level share deformation. The reinforced rubber isolation bearings’mechanical property is the same as the ordinary rubber isolation bearings’ when the deformation is small (atthis point the steels are at relaxed state). But the level stiffness and resilience of the reinforced rubberisolation bearings has an obviously improve due to the effect of steels when big share deformation takesplace, which also improves the rubber bearings’ energy dissipation and the resistance to overturnperformance.(5) Making research on the mechanical properties of the reinforced rubber isolation bearings withdifferent steel diameters, and compared with the ordinary rubber isolation bearings without steels. The levelstiffness and the recovering ability increase with the increasing of the diameter of steels which are insertedin the reinforced rubber isolation bearings. By this analysis, we can change the reinforced rubber isolationbearings’ level stiffness and the recovering ability by adjusting the diameter of the steels. What is more, itwill improve the isolation effect of the reinforced rubber isolation bearings.(6) On the basis of these analysis, we have an experimental comparative study between thereinforced rubber isolation bearings and the ordinary rubber isolation bearings. According to the results ofthe two bearings, this paper studied on the basic performance parameter of the bearings, such as maximal resilience and the effect of the level and equivalent stiffness in addition to the analysis of the parametervariation. And proved that the reinforced rubber isolation bearings can not only provide a greater level ofresilience and stiffness, but also improve the bearings’ energy dissipation and the resistance to overturnperformance. By this it verified the superiority of the reinforced rubber isolation bearings.