SEISMIC DESIGN APPROACH FOR TORSIONAL EFFECTS ON RC DUCTILE BUILDINGS

<p><em>This study investigates the influence of torsional effects on the seismic performance of reinforced concrete (RC) ductile buildings and provides a framework for their analysis and design. Key considerations include the relative positions of the center of mass (CM) and center of stiffness (CS), stiffness distribution, and the control of lateral displacements and inelastic rotations. Equations for determining total forces, torsional stiffness, radius of rotation, and system displacements under eccentric seismic loading are presented, along with methods to constrain inelastic twist in asymmetrical systems. The research adopts Paulay’s classification of torsional systems into torsionally unrestrained and restrained categories, highlighting design strategies to limit torsional rotations while maintaining ductility. A numerical example illustrates the application of these concepts, demonstrating the design of a system with limited twist through optimal placement of vertical walls and consideration of ductility capacities. The findings emphasize the critical role of torsional considerations in modern seismic design, providing engineers with analytical tools to enhance structural resilience and prevent excessive damage during strong earthquakes.</em></p> <p> </p>