evaluation of effective uncertainty in the behavior of reinforced concrete frames

with respect to the new aspects of earthquake engineering in the area of performance besed design, accurate estimation of structural response becomes more important. this requires precise recognizing of relevant parameters in the behavior of structures and using proper methods for applying the effects of distribution of these parameters in the desired response. in this study the effect of distribution of existing uncertainties on the important parameters corresponds to the behavior of reinforced concrete frames is studied. for this purpose by using sensitivity analysis of tornadodiagram and first-order second-moment approximation method, the important parameters in different behavior states of structure are recognized and by using first-order second-moment approximation method and monte carlo simulation, the effects of uncertainties in the selected response are combined together and results of these two methods are compared. the results indicate acceptable accuracy of first-order second-moment approximation method for combining the effects of uncertainties on the desired response and efficacy of this method for classification of uncertainties.