Évaluation de la vulnérabilité sismique des bâtiments à ossature de bois en milieu urbain

Abstract

Earthquakes are significant natural hazards that cause considerable social and economic losses to the built environment in regions prone to seismic activity. The considerable losses from past earthquakes have highlighted the critical need for assessing the seismic vulnerability and risks of existing structures. In Quebec, existing wood frame houses were built using conventional construction methods with prescriptive requirements without engineering seismic calculations for lateral capacity to resist earthquake forces. It is crucial to assess the seismic vulnerability of these houses for the quantification of their expected performance after earthquakes and for pre-earthquake planning for seismic mitigation. The objective of this study is to evaluate their vulnerability by developing analytical capacity and fragility characteristics and analyzing their structural response to seismic forces. Additionally, , the study estimates the potential losses these houses could experience under various seismic scenarios, providing essential data on their performance during earthquakes of different intensities. In the first part of this study, a simplified analytical methodology is used to develop the capacity curves for one-story and two-story houses based on structural characterization of six prototype houses. Displacement and acceleration-based fragility curves are then developed based on drift and accelerations thresholds available in literature for various damage states in structural and non-structural components. In the second part, the potential earthquake induced direct economic losses of these houses were studied under multiple scenarios, considering 60 earthquake scenarios with varied magnitude, distance and site class. These loss scenarios were analyzed using the Hazus software, and a predictive model was then developed to estimate losses in terms of building loss rate, defined as the ratio of economic loss divided by the total replacement cost of the building. Equations were developed to correlate the loss rates directly as a function of seismic intensities including peak ground acceleration and spectral accelerations at 0.3s and 1.0s, respectively. The study demonstrated that two-story houses are more vulnerable and experience more damage during moderate earthquakes compared to one-story houses. The predictive loss rate equations are particularly useful for rapid assessment of direct economic losses in the framework of regional scale seismic risk assessment studies.

Date	22 Aug 2025
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Ahmad Abo El Ezz (Supervisor)