THE RATIO OF DISPLACEMENT AMPLIFICATION FACTOR TOFORCE REDUCTION FACTOR

摘要

For Seismic design, it is important to estimate, maximum lateral displacement of structures due to severearthquakes for several reasons. Seismic design provisions estimate the maximum roof and story driftsoccurring in major earthquakes by amplifying the drifts obtained by elastic analysis with a deflectionamplification factor (DAF). This factor depends on various parameters, of which the force reduction factor(FRF) is the most important one. The main objective of this paper is to evaluate the ratio of DAF to FRF(DAF/FRF). It is shown that the ratio DAF/FRF equals to the ratio of the system ductility factor (μ) to theductility reduction factor (Rμ). So the ratio μ /Rμ was evaluated instead of DAF/FRF using the various Rμ(proposed in current years).The results indicate that the ratio of DAF/FRF differs to those proposed by seismic provisions such asNEHRP, IBC and Iranian seismic code (standard no. 2800), and they need to be modified.