determination of the response modification factor for precast rc moment-resisting frames

in the process of designing a typical structure, due to the concept of overstrength, it is assumed that the structure is able to dissipate the seismic energy through inelastic behavior. so as not to overestimate the seismic loads, which results in overdesigned members, the applied loads should be divided by a factor named as “response modification factor” or “r factor”. with respect to precast structures, most of the design codes have not proposed a specific response modification factor and much more research must be conducted. in this paper, three different types of structures are designed in the common way and also modeled by the use of a simplified model (including beams, columns, and springs) in the software abaqus. several nonlinear static (pushover) and nonlinear dynamic time-history analyses are performed using the horizontal components of real earthquakes. afterwards, the seismic behavior of precast reinforced concrete (rc) moment-resisting frames are investigated. the response modification factors of the designed structures are calculated from the results of the nonlinear static analyses. the results of the nonlinear dynamic time-history analyses are also used to determine the r factors. finally, a comparison is drawn between both of these methods. eventually a response modification factor of 6 is suggested for these kinds of structures.