Effect of the transverse reinforcement spacing in nodal zones on the seismic behavior factor of RC frames according to Algerian design code RPA99/version2003

The seismic behavior of reinforced concrete (RC) frames is significantly influenced by the confinement provided by transverse reinforcement. This study investigates the effect of transverse reinforcement spacing on the seismic behavior factor (R) of regular RC frames. The objective is to determine which spacing provides an R value in accordance with the Algerian seismic design code (RPA99/version 2003). To evaluate this effect, nonlinear pushover analysis is performed for each configuration. The confined concrete properties are defined using Mander’s model, accounting for variations in compressive strength and strain capacity due to different stirrup spacings. The seismic behavior factor (R) is computed based on the overstrength factor (Rs​) and the ductility factor (Rµ​), derived from the capacity curves. The results of this study will provide insights into the influence of confinement on ductility and overstrength, allowing for the identification of an optimal stirrup spacing that ensures compliance with the RPA99/version 2003 seismic design code. The findings will help improve reinforcement detailing recommendations for enhanced seismic performance of RC frames.