توسعه روش طراحی برای سازه‌های مجهز به ترکیبی از میراگرهای فلزی جاری شونده بر اساس اهداف عملکردی

One of the effective ways to mitigate earthquake damage in structures is passive control of structures. Yielding metallic dampers economic passive control devices. Not only yielding metallic dampers are easy to erect, but they can also be used as a passive control systems easily. In this paper, the aim is to develop a design procedure for steel structures equipped with a combination of yielding metallic dampers so that, dampers will experience specific nonlinear behavior when subjected to various seismic hazard levels. For this purpose, the first step is providing seismic hazard spectra with different return periods for the intended site of construction. In this research, this step has been taken by using the Tehran probabilistic analysis hazard project data and then plotting uniform hazard spectra with 75-year, 475-year, 975-year and 2475-year return periods. After determination of uniform hazard spectra with mentioned return periods, behaviors of structures equipped with yielding metallic dampers have been investigated in the form of one-storey one-span, one-storey two-span and multi storey multi span frames. Required equations for behavior of these structures under monotonic loading is developed. In the beginning of design process, the performance criteria for the structure and the damper is set and by using the derived equations, design of single degree of freedom frames based on performance criteria has been carried out. These single degree of freedom structures have different periods and strength reduction factors. After designing the single degree freedom structures, nonlinear static analysis results have been compared with result of nonlinear time history analysis. For this purpose, 7 earthquake records have been chosen and scaled based on Iranian code of practice for seismic resistant design of buildings and used for dynamic analysis. Results showed that all performance criteria of 75-year and 475-year hazard levels have been satisfied but for 975-year and 2475-year hazard levels, six cases have not satisfied the desired critera with 6 percent error. In order to verify the presented numerical analysis of multi degree of freedom structures, an experimental study has been chosen and the results of these two works have been compared. This verification showed that the presented analysis can model the structures and dampers with acceptable accuracy. Performance criteria of multi degree freedom structures have also been proposed. Three, 3-storey, 6-storey and 9-storey buildings equipped with dampers have been designed and based on proposed method and the desired performance of dampers have been achieved. Time history analysis have been carried out for each return period. For these analyises, 7 earthquake records were chosen and scaled based on Iranian code of practice for seismic resistant design of buildings. Comparison of performance point displacement levels and the displacements obtained from 28 nonlinear analyses, showed up to 13 percent error. Meanwhile, the displacement levels of each set of dampers for 75-year, 475-year, 975-year and 2475-year return periods, confirmed efficiency of proposed design method and all dampers met the mentioned performance criteria. The results also showed that when hazard level increased, the difference between the results of nonlinear time history analyses and static nanlinear analyses have also increased.