Analyses On The Seismic Retrofitting With Rubber Bearing Isolation For Frame Structural Office Building And Seismic Damping Measurements For Floating Equipment

There are many cases of seismic retrofitting and reconstruction of old buildings by using seismic isolation technology at home and abroad.This technology can decrease the seismic response of the superstructure and significantly increase the overall seismic resistance of the structure by adding seismic isolation devices to the bottom of existing buildings without affecting the superstructure.After the seismic isolation technology is employed,while the structure and the internal floating equipment are protected at the same time,but for the higher important instruments and equipment whether there is a need to take further additional seismic damping measurements on the basis of building which has been adopted seismic retrofitting and reconstruction worth exploring.In this paper,taking the project of seismic retrofitting and reconstruction of old building for an example,this article is for the purpose of to the technical analysis process of measurements of the seismic retrofitting with rubber bearing isolation for frame structural office building carrying on the system combing with the discussion,and putting on the feasibility analysis of whether additional shock absorption and isolation further measures are needed for the floating equipment inside the building after seismic retrofitting with rubber bearing isolation.The full text has mainly done the following three aspects:1.Reading a large number of relevant literature at home and abroad,and combing the current situation of the application of the seismic retrofitting with rubber bearing isolation technology for existing buildings.2.The case office building is a four-story,single-span with cantilevered reinforced concrete frame structure,the entire process analysis of the seismic retrofitting with rubber bearing isolation is carried out.Based on the comprehensive analysis of the seismic resistance limitation of the original structure according to the requirements of the seismic resistance,a proposal is made for the reconstruction and reinforcement with the rubber bearing isolation for the case reinforced concrete frame structure office building.According to the scheme of seismic retrofitting with rubber bearing isolation,finite element analyses for the isolation system retrofitted with both of rubber bearings and lead rubber bearings are carried out for the updated structure of the existing office building.Also,the seismic analytical results comparison between the base isolated new structure and the original structure are carried out.The analysis results show that due to the severe lack of seismic resistance,it is difficult to use the traditional seismic retrofitting method with poor economics to reinforce the original structure,while after the isolation design,analyses results show that both the cross-section enlargement strengthening for part of columns and steel wrapping strengthening for part of columns and beams are jointly used to withstand the earthquake requirements of 8 degrees(PGA=0.2g).Analyses are conducted by using the ETABS program and the PKPM design software comparatively.PKPM software is used to analyze structural dynamic characteristics,and ETABS software is used to analyze structural nonlinear dynamic time history.Three possible isolation bearing arrangement schemes,including base isolation,the first-story-column-bottom isolation and the first-story-column-top isolation,are carried out and compared with each other.Finally,the first story column bottom isolation together with part of the beams and columns being strengthened is adopted as the retrofitting scheme for the office building.3.Taking the example of an important equipment placed on the second floor of the case office building as an example,a simulation analysis is carried out to analyze the response of the floating equipment in the building to further adopt the additional suspension and shock absorption measures,which the first-story-column-bottom isolation and reinforcement of the structure has been done.A comparative analysis of the seismic damping effects of not adopting additional suspension and shock-absorbing measures in the first-story-column-bottom isolation and reinforcement building,and the use of seismic damping measurements for floating equipment in non-isolated and reinforced structure,expectations for providing experience and reference for secondary protection of important floating equipment.