From rapid visual survey to multi-hazard risk prioritisation and numerical fragility of school buildings

Abstract

Regional seismic risk assessment is paramount in earthquake-prone areas, for instance, to define and implement prioritisation schemes for earthquake risk reduction. As part of the Indonesia School Programme to Increase Resilience (INSPIRE), this paper proposes an ad hoc rapidvisual-survey form, allowing one to (1) calculate the newly proposed INSPIRE seismic risk prioritisation index, which is an empirical proxy for the relative seismic risk of reinforced concrete (RC) buildings within a given building portfolio; (2) calculate the Papathoma Tsunami Vulnerability Assessment (PTVA) index, in any of its variations; (3) define one or more archetype buildings representative of the analysed portfolio; (4) derive detailed numerical models of the archetype buildings, provided that the simulated design is used to crosscheck the model assumptions. The proposed INSPIRE index combines a baseline score, calibrated based on fragility curves, and a performance modifier, calibrated through the analytic hierarchy process (AHP) to minimise subjectivity. An attempt to define a multi-hazard prioritisation scheme is proposed, combining the INSPIRE and PTVA indices. Such a multi-level framework is implemented for 85 RC school buildings in Banda Aceh, Indonesia, the most affected city by the 2004 Indian Ocean earthquake-tsunami sequence. As part of the proposed framework, two archetype buildings representative of the entire portfolio are defined based on the collected data. Their seismic performance is analysed by means of non-linear static analyses, using both the analytical simple lateral mechanism analysis (SLaMA) method and numerical finite-element pushover analyses to investigate the expected plastic mechanisms and derive displacement/drift thresholds to define appropriate damage states. Finally, non-linear dynamic analyses are performed to derive fragility curves for the archetype buildings. This paper demonstrates the effectiveness of the INSPIRE data collection form and proposed index in providing a rational method to derive seismic risk prioritisation schemes and in allowing the definition of archetype buildings for more detailed evaluations/analyses.