ESTIMATION OF THE SEISMIC RISK WITH CONSIDERATION OF CAPACITY DEGRADATION OVER TIME

The dependence of mankind on the urban built environment is an integral part of culture that is so firmly embedded in our daily life that we are mostly unaware of its existence, as long as functionality is provided. The aging of our structures and the action of natural hazards, such as earthquakes, threaten the functionality of our urban environment and extraordinary expenditures are required to just maintain the status quo. Throughout the world, buildings are reaching the end of their useful life and develop new pathologies that increase their seismic risk, an effect that we aim to capture. In the paper, first, a methodology for structural performance assessment with consideration of capacity degradation over time is presented, utilizing IN2 analysis and an extension of the PEER probabilistic framework to rapidly achieve accurate estimates of limit-state exceedance probabilities of deteriorated structures. In the second part the methodology is applied to an example of a three-storey asymmetric reinforced concrete building. At this stage of the study only an influence of corrosion on longitudinal and transverse reinforcement of the structural elements is considered in the estimation of the seismic risk. The N2 method is used for seismic performance assessment of the structure. It is shown that the capacity in terms of the maximum base shear, as well as in terms of the maximum ground acceleration corresponding to limit states in the nonlinear range, is reduced over time, since the corrosion affects the capacity of both the beams and columns. Consequently, the expected frequency of violating life-safety or near-collapse limit states over the time interval increases in comparison to the typical case where the strength deterioration is neglected.