Seismic behavior of structures with dampers made from ultrahigh damping natural rubber

This study focuses on a new damping material for structural dampers, Ultra High Damping Natural Rubber (UHDNR). UHDNR has several advantages as an energy dissipation material for structural dampers. First, the mechanical properties of UHDNR are less dependent on frequency and temperature than a typical VE material. Second, the temperature increase in UHDNR damper during dynamic loading is relatively small, and the changes in the mechanical properties due to this temperature increase are negligible. Finally, UHDNR recovers its original mechanical properties after a short relaxation time if excessive strains are not applied.; This study includes experimental tests to evaluate the mechanical properties of UHDNR, the development of analytical models for structural dampers made from UHDNR, the development of preliminary design analysis procedures to be used in the seismic design of structures with UHDNR dampers, and an investigation of the seismic performance of structures with UHDNR dampers from nonlinear time history analysis. Retrofit studies of a non-ductile reinforced concrete frame building and a steel moment resisting frame building were performed. The seismic performance of frame buildings with UHDNR dampers was compared to that of frame buildings with viscoelastic (VE) dampers.; It was concluded that strain amplitude dependence is the most dominant factor among the effects of strain amplitude, ambient temperature, and loading frequency on the mechanical properties of UHDNR material. A rate-independent analytical model, focused on the strain amplitude dependence, was proposed. A rate-dependent analytical model was also proposed to address the relatively small loading frequency dependence. The proposed models show good agreement with the experimental results. The retrofit studies of a non-ductile reinforced concrete frame building and a steel moment resisting frame building demonstrate that the UHDNR dampers greatly decrease story drift and internal forces in the columns, beams, and other structural components. The seismic performance of UHDNR damped system is satisfactory with respect to the intended seismic performance. When a design temperature range is considered (in these studies, 10°C to 30°C), the UHDNR damped system outperforms the VE damped system, because the UHDNR material is less sensitive to ambient temperature and loading frequency than a typical VE material.