Review of confidence factor in EC8-part3: a european code for seismic assessment of existing buildings

Abstract

The built environment, both historic and of recent construction, is exposed to high level of seismic risk due to increasing level of seismicity around the world. Thus, it is necessary to assess the existing building performance to current level of seismicity in order to perform the cost-effective interventions. EC8-Part 3 is devoted to seismic assessment/retrofitting of existing buildings. This document introduces an adjustment factor to account for epistemic uncertainty, called “confidence factor (CF)”. CF is based on the level of knowledge of the structural properties such as geometry, reinforcement layout and detailing, and materials. This solution, plausible from a logical point of view, cannot yet profit from the experience of use in practice, hence its soundness needs to be investigated in real applications. This paper proposes a probabilistic based method to calibrate CF, which can simulate the entire assessment procedure conditional on the acquired knowledge. The method is then applied to six-storey three-bay reinforced concrete frame to assess the role of CF. The obtained CF's values are then critically examined and compared with code-specified ones. The critical problems of using a single factor in seismic assessment of existing buildings are pinpointed.