Nonlinear dynamic behavior of new and existing structures using the stiffness decoupler seismic isolation system

The main characteristics of a new type of base isolation system, SDBIS, are presented in this research. The new isolation system was investigated both experimentally and analytically to verify its applicability to new and existing buildings. An experimental methodology was presented to determine the dynamic characteristics of SDBIS. The efficiency of the new system as a seismic isolation technique according to the Uniform Building Code, UBC, has been verified experimentally. Charts for the nonlinear stiffness, nonlinear damping and the restoring strain energy of the main component of SDBIS, steel pipes filled with concrete, have been developed to be used for preliminary designs.; The nonlinear free and forced vibrations of the system have been numerically simulated considering the nonlinear behavior of the main components of the system. The provisions of the Uniform Building Code to determine the natural period of isolation systems were proved to be inappropriate for SDBIS. A set of response spectra of masses supported by SDBIS, has been developed under the effect of some credible worldwide earthquakes. A Displacement-Control Mechanism was presented. The nonlinear characteristics of that mechanism were also included in the response spectra.; The efficiency of SDBIS in reducing the transmissibility of ground motions to the supported structures was investigated both experimentally and numerically. The results indicated significant improvement in the structures' response.; A survey was conducted to address the main available, commercial computer programs that can handle the major characteristics of SDBIS. The most appropriate software that could be used as a numerical tool to simulate SDBIS was addressed.; SDBIS was investigated as a new retrofitting scheme for existing nonseismic buildings. Both the structural and economical impacts of SDBIS as a retrofitting technique were compared with some of the main conventional methods of seismic upgrading. SDBIS was proved to be an effective retrofitting technique. The design and the construction of a new shaking table, as part of this research, are briefly presented.