Ductility in Seismic Design

Over the last decades the recognized means of survival, generally termed ductility, that is the ability for inelastic deformations, was extensively explored. This very desirable property of structures enables the chosen level of resistance with respect to earthquake induced forces to be maintained even after the ground shaking of high intensity. Moreover, in well detailed structures ductility capacity allows significant energy to be dissipated. Thereby damping is provided which enables large earthquake induced lateral displacements to be kept within limits, dictated by stability criteria. While ductility in the flexural mode of member response, quantified in terms of curvature ductility, can generally be readily achieved, there are simultaneous structural actions, such as shear, which may interfere with or restrict the development of the desired level of ductility. In such cases special attention need to be paid to the detailing of potential plastic regions. This brief review addresses primarily these issues of plasticity in reinforced concrete structures.