Rationalizing Response Reduction Factor R for better Performance of Reinforced Concrete Framed Buildings

Abstract

Seismic resistant design philosophy incorporates the non linear response of the structure by using appropriate Response reduction factor (R). The value of R is directly related to the ductility level provided in the structure. Greater the assumed value of R, grater will be the ductility in the structure. The non linear response of structure will be more than the linear response because of material non linearity, factor of safety in load combinations, structural redundancy and ductility. Use of higher values of R is encouraged because of significant reduction in base shear leading to more economic structure. Value of R for reinforced concrete structure depends on the type of framing system. Proposed IS 1893 draft classifies framing into three categories i.e. 1) Ordinary Moment Resisting Frame (OMRF), 2) Intermediate Moment Resisting Frame (IMRF), and 3) Special Moment Resisting Frame (SMRF). In the paper, study is done to compute the value of R, component wise of a G+4 storey building designed for all seismic zones, considering ductile and non ductile design provisions and the same is compared with the assumed R to check the safety of the structures. R provided is computed from the obtained pushover curves.