Analysis Of Seismic Isolation Of A Steel Frame Structure With Rubber Isolation Bearings Beyond Specification Limits

Compared to traditional seismic principle, isolated structure provides people with new ways to reduce seismic damages using energy-dissipated devices in isolation layer instead of structure itself. Setting isolation layer at the bottom of the structure can reduce natural frequency of the structure, change natural period, dissipate energy from the earthquake, thus it will weaken seismic response of the upper structure. Nowadays, with gradual study of isolation technology, there has formed a relatively completed theory of isolation which has been widely used in Japan, USA and Europe. This thesis sets a isolation layer with laminated rubber bearings for a steel frame structure beyond specification limits, conducts comparative analysis of seismic performance between isolated structure and non-isolated structure, then it compares isolation effects between structure beyond specification limits and structure under specification limits, also it has seismic checking for laminated rubber bearings.First of all, this thesis describes isolated structure, principles of isolation, the composition and mechanical properties of laminated rubber bearings. Then it describes principles and characteristics of common kinds of seismic response analysis. Basing on former work, this thesis uses a steel frame structure as example, sets a isolation layer in it, compares the response under frequent earthquake of isolated structure with non-isolated structure using software SAP2000. Then it tells the effect of laminated rubber bearings and shows working rules of reducing earthquake. Also this thesis compares isolation effects between structure beyond specification limits and structure under specification limits. What’s more, by using response spectrum method and time history method, this thesis analyzes seismic response under design earthquake and compares the results of two methods. At last, this thesis calculates seismic response under rare earthquake and conducts seismic checking for laminated rubber bearings.The comparison between isolated and non-isolated structure shows that laminated rubber bearings play an obvious role in reducing effect of earthquake. Comparative isolation effects between structure beyond specification limits and structure under specification limits show that, isolation layer has more effective effects in former structure. The seismic check of isolated structure can meet standards under frequent earthquake, design earthquake and rare earthquake.Using rubber isolation bearings is one of the earliest isolation methods which people begin to study and use in daily life.Therefore, compared to great number of buildings, the application of isolation technology has not been widely used enough. In this thesis, the analysis of seismic isolation of steel frame structure is only an example. It hopes that this thesis can serve as a reference for similar structures With principles of isolation being mature, the isolation technology becoming gradually innovated, the use of rubber isolation bearings will be more and more widely applied in the future.