Evaluation of response modification factor for shear wall-flat plate structural systems

Abstract

Flat Plate (FP) structures are not suitable for use in zones of high seismicity due to their subpar performance in lateral loads. However architectural and functional benefits from adopting this system have contributed to the popularity of flat plates in our country. Recently shear walls are bring used alongside columns in flat plate structures to make structures stiffer and more resistant to seismic loading. Shear Wall – Flat Plate (SW-FP) structural systems are still undefined in building codes since their seismic behavior is little understood. The principle aim of this research is to study the nonlinear behavior of SW-FP systems under design basis earthquakes (DBE) in moderate seismic zones and figuring out the response modification factor for SW-FP structures. To understand the nonlinear behavior of structures, nonlinear static or pushover analyses were performed for SW-FP systems. Performance of the buildings, e.g. maximum displacement, base shear capacity, hinge formation were measured according to ASCE 41 ‘Displacement Coefficient Method’ and FEMA 440 EL ‘Capacity Spectrum Method’. Response Modification Factor defines the level of inelasticity expected in structural systems during an earthquake event. It is used to reduce the design forces in earthquake resistant design and accounts for damping, energy dissipation capacity and over strength of the structure. The value of response modification factor for SW-FP systems could not be found in many of the widely adopted building codes. Upon performing extensive analyses, response modification factor for SW-FP systems and FP systems have been suggested in the ranges of 6 – 7 and 4 – 5 respectively. The value suggested can be used in design and further researches should be carried out to adopt that value in building codes.