بررسي تغييرات پاسخ سازه اي بتني مسلح در اثر تغيير جهت اعمال زلزله توسط روش تحليل ديناميكي چندمولفه اي ، MIDA

Incremental dynamic analysis (IDA) is one of the most efficient analytical methods to evaluate seismic behavior of the structures. Obtaining relatively exact results specially in the case of concrete structures requires multi-component IDA (MIDA) analysis on three-dimensional models. In MIDA analysis determination of the incident angle is very important, because it considerably affects the result of analysis. It is impossible to determine incident angle of earthquakes due to their random nature .In this paper, the effect of incident angle variation on the response of structures is investigated and has tried to establish a relationship to obtain critical value of incident angle which produces the maximum response in the structure. For this purpose two three-story concrete building is selected one having regular plan and one irregular. Then selecting some accellograms randomly and by implementing MIDA analysis this issue is investigated. Modeling and analyses is accomplished using Opensees environment which is a finite element based computational tool. The results are plotted in graphs which show the amount of variation for different cases and show the sensibility of each structure to incident angle in different intensity for each accellogram. Because of fewness of analyses, results aren't general but it could make a good perception of the issue and provides a view of amount of influence of incident angle on concrete structures.