Seismic Researches On Rubber Base Isolated Structures With Frictional Damper

The researches in the paper are carried out with the support of TYUT youth fund and natural science fund of Shanxi province. The researches belong to the fields of seismic isolation and reduction, which concern seismic base isolation system and frictional damping.Based on FEM theory and proper component model and isolated element, the paper analyzed dynamic time-history of one frame structure without isolation, with friction isolation, with rubber isolation and with rubber bearing with frictional damper by the way of software ANSYS, at the same time discussed the economy and the method of design.This paper studies the regularity of earthquake response under different conditions of concrete structure, analyzes the characteristics of isolation by comparing the earthquake react of three basic isolation system, and especially studied the collocation of rubberrestoring force and frictional damp in frictional damp rubber isolation, referred One ratio R, named the ratio of damp and restoring force, indicated the ratio relation of rubber restoring force and frictional damp. Some valuable conclusions is gotten by analyzing the nature of isolation under different R, then analyzed the technical economy. At last this paper discussed the ways of design about base isolation structure.The frictional bearing is modeled by node to surface contact, it is better to imitate friction. And this is fewer in previous papers. It is known to us that contact is a strong nonlinear problem, if model is established improperly, the result will be mistaken. Therefore the method is verified in this paper using node to surface contact to imitate friction bearing. Through contrasting with calculate example, proved that the method is feasible and the results are credible. On the other hand, The restoring force model of rubber bearing in this paper is adopted bilinear model, the vertical force-deform is adopted linear elastic model, so the mechanics model of rubber bearing is established by two elements: horizontal direction is adopted combin40 spring element imitated by the strong model of bilinear considering the effect of viscous damp and vertical linear spring element is adopted combinl4.Study in this paper shows that upper structure is mainly overall translation, the acceleration still transmits upward, shear and displacement between layers is little and the maximum shear occurs in bottom layer. When friction isolation, shear and displacement between layers and the maximum acceleration is larger than rubber isolation, the maximum shear may generate in middle layers.when using friction damp rubber isolation, Shear between layers displacement between layers and the acceleration are closedto rubber isolation, the maximum displacement is less than rubber isolation, but the remnant displacement is obviously less than friction isolation. So it is better than rubber isolation and friction isolation in the nature of isolation. If proper frictional damper is adopted in both rubber and friction isolation, it may reduce obviously the acceleration and shear transmitted to upper structure. Choosing suitable friction bearing, if using less restoring force, it can get better effect of isolation. When R=10~3. 3, the acceleration is less than without isolation structure in top, the remnant displacement is not too larger; When R=2 and R=l, the acceleration is larger than R=10^-3. 3 in top, These results can be used in further analysis and actual engineering adopting friction damp rubber isolation.Whether building isolation used or not, it depends on its technical economy. Based on comparing the frame structure with frictional rubber isolation and the frame-shear wall structure without isolation this paper studied the technical and economical indexing of frame column at the same condition of shock, the analytic results shows the former has better quake-proof nature and no less economy than the latter.Based on the former study, this paper analyzed the methods and the steps of isolation design, discussed the ways and the content of optimum design, contacted the isolation design with the optimum design, made the isolation structure serve quake-proof, reduction damage and economic construction better.