Seismic Reliability and Risk Assessment and Targeting of Code-Compliant Reinforced Concrete Buildings

Structural safety is one of the most challenging tasks in civil engineering, as its evaluation implies considering all the sources of uncertainty appropriate to a probabilistic context. One of the main objectives of a building code is to provide practitioners with a series of rules capable of ensuring an adequate and uniform safety margin and implicitly managing this inherent uncertainty. As a consequence, the present study focusses on assessing the seismic safety of newly designed code-compliant buildings using the well-known reliability analysis. In this way, it would be possible to assess the effectiveness of the current Italian Building Code on seismic safety in Italy. In the first part, a framework capable of carrying out seismic reliability analysis of reinforced concrete buildings will be developed. The models will be characterised by a resisting scheme composed of shear walls or frame elements, considering both bare and infilled conditions. This implies the implementation of a procedure to parametric design these prototype buildings for all the possible levels of seismic intensity, and the execution of several nonlinear dynamic analyses for assessing their vulnerability. Finally, fragilities are combined with seismic hazard curves to assess the seismic safety of all 7901 Italian municipalities. Second, a hands-on reliability-targeted approach will be proposed to overcome the hazard-dependent reliability outcomes of the current code-conforming design philosophy. Specifically, a new behaviour factor explicitly calibrated with a pre-defined target level of safety will be evaluated for the previous building archetypes. The last part of the work will focus on including the risk term in the assessment of code-compliant structures. Therefore, a procedure to convolute the failure rates with a loss metric will be established. Thus, this framework will be applied to the investigated archetypes. Seismic risk maps in terms of expected annual loss will be presented and compared with failure rate maps. In this way, it will be possible to evaluate how non-uniform reliability affects the risk.