Seismic risk is a well-known issue in Quebec, but it is not only the shaking that would cause the most damage in the event of a major earthquake in Montreal. This is the observation of a recent study for the Institute for Catastrophic Loss Reduction. The study highlights the significant risk of fire following a seismic event, due to the high potential for fires to start and spread, particularly given the extensive use of wood in Montreal building construction. It is therefore essential that firefighters are safe during earthquakes and operational afterwards, as they will have to cope with a lot of demands. It is for this reason that Montreal's fire stations are being seismically assessed in this project. The first step is to establish an inventory of the fire stations, including identification information, structural and non-structural data and local soil conditions. The study reveals that 71.2% of the fire stations were built before 1975, when dynamic analysis and ductility considerations was introduced to determine seismic design forces in the National Building Code of Canada, and 39% before 1953. The most common structural types are concrete moment frames (32%), steel braced frames (17%), steel moment frames (15%) and unreinforced masonry bearing walls (14%). In addition, most of the fire stations contain unreinforced masonry walls, either as part of the structural load-bearing system or as a façade or non-structural partition wall. Specific architectural features of the fire stations are identified, such as hose towers and garage doors. Typologies are then identified based on the structural and geometric characteristics. This process defines six types of fire station on the island of Montreal. Based on the inventory information and the visit of 25 fire stations, buildings are assessed using a rapid index evaluation method. Each fire station is assigned a structural and a non-structural index, and a priority ranking is established with a view to a detailed assessment, unless exempted. At the end of the rapid assessment, 82% of the fire stations require further assessment, with the highest priority. The structures with the worst ratings are unreinforced masonry load-bearing walls. Finally, the fire stations are assessed by simulating earthquake scenarios. A numerical assessment tool has been developed for fire stations. A seismic hazard, inventory, fragility and impact model are defined. Precalculated fragility data are used for the model. An earthquake whose epicentre is located in the centre of the island and three magnitudes are chosen. For each scenario, the probability of damage to each fire station is calculated. The simulation for a magnitude 6 earthquake and a median level of ground motion, it is found that 74% of fire stations are in a « Moderate » damage state and the rest is in a « Slight » damage state. A mean damage factor is used to determine the state of damage to each fire station, and a ranking by inspection priority is established. A detailed assessment of the most critical fire stations and analyses of the 6 models defined could be done.
Lessault, T. (Author),
Abo El Ezz (Supervisor) &
Nollet (Co-supervisor),
24 Nov 2023Student thesis: Master's thesis › Master in Engineering: Construction Engineering