Research On New SMA Rubber Bearings And Seismic Isolation To Bridge Structures

Superelasticity is one of the most important mechanical behaviors of shape memory alloy, researches on superelasticity are the focus for application of shape memory alloys. This thesis presents a designing and study of several new types of SMA-Rubber Bearings and their application for seismic isolation in bridge structures. First, the research and development of SMA in the field of seismic base isolation, energy dissipation and vibration control of bridge structures was reviewed and analyzed. The further using of SMA in vibration control of civil structures was proposed. Second, based on the basic theory, the constitutive models describing superelasticity behavior of shape memory alloys were summarized here and the factors influenced superelasticity were analyzed. The advantages and disadvantages of every kind of constitutive model were also summarized. Third, the SMA rubber Bearings'optimized designing are proposed and designed utilizing superelasticity of SMA materials, the corresponding theoretical models are developed and design methods are given. Fourth, in order to demonstrate the SMA rubber Bearing's feasibility and get full understanding of working performance of the SMA rubber Bearing, a detailed experimental investigation is carried out from which the effects of vertical loads, strain levels, as well as frequencies are discussed. The theoretical model is verified by the experiment. Finally, based on the results of the experiment, dynamic responses of a bridge structure model with SMA rubber Bearing are analyzed, and the seismic isolation performances of the bearing are discussed. Vibration control theory and methods for bridge structures are investigated, and the control effectiveness are analyzed, the disadvantages of the SMA rubber bearings in this paper and the emphases for improvement in the future were pointed out.