Lifetime Seismic Performance of Aging Structural Systems

The seismic performance of structural systems exposed to aggressive environments has to be considered time-variant. Current capacity design criteria are time-invariant and do not account for the interaction with environmental hazards. In fact, for aging systems the energy-dissipating collapse mode may vary over time due to a reduction of both strength and curvature ductility of critical cross-sections where plastic hinges may occur during a seismic event. In this study the lifetime seismic performance of concrete structures is investigated in both probabilistic and deterministic terms. Static and dynamic non linear analyses are carried out on a three-story concrete frame to evaluate the effects of damage on the time evolution of seismic performance indicators. The results show the important role of a life-cycle approach for both seismic assessment of existing structures and seismic design of new structures.