Use of overstrength and inelastic response in seismic design

Inelastic analysis procedures are more dependable means for predicting the actual seismic response compared with elastic analysis methods. Encouragement to use the former procedures is still limited and designers tend to favour elastic analysis procedures. The permissible reduction in response parameters obtained from elastic analysis unlike those from inelastic analysis procedures discourages the effective use of the latter analysis methods in design. This paper proposes a simple and theoretically-based approach that utilises inelastic structural response in design. To describe the approach, the correlation of seismic demands obtained from ineleastic and elastic analysis procedures carried out using a wide range of reinforced concrete buildings of different characteristics, ranging from 8 to 60 storeys, is investigated. Verified fibre element models and diverse input ground motions are employed in the inelastic simulations. The presented approach enables designers to arrive at a realistic and cost-effective design without compromising safety.