Modified equations for displacement-based method of steel braced reinforced concrete structures

For reinforced concrete (RC) structures located in earthquake prone areas, inherent brittle behavior of concrete may have adverse effects on their seismic performance. Buckling-restrained braces (BRBs) are commonly employed as ductile bracing components located in seismic areas where configuring these elements in RC frames can develop a ductile steel braced reinforced concrete structures. By evaluating key limit states governing dual frame design, this study aims to present a direct displacement-based design (DDBD) method as an alternative approach to the seismic design of steel braced reinforced concrete structures. The force–deformation expression of the steel braced reinforced concrete structures was developed. The new approach for numerical modeling was proposed and validated to simulate the nonlinear behavior of dual system. Then, a number of steel braced reinforced concrete structures considering different height and bracing configurations were designed to perform nonlinear time-history (NTH) analysis under real earthquakes. The seismic response including the maximum displacement profile of all models was acquired. The maximum value of least mean square error was calculated 11% for high-rise sample models that the predicted displacements can be reliably matched with the demanded displacements of the steel braced reinforced concrete structures. The analytical results of the current study indicate that DDBD approach can be used to design ductile steel braced reinforced concrete structures in seismic zones.