Seismic vulnerability assessment of pre-1945 unreinforced masonry buildings located in Queensland, Australia, using an index-based approach

The Australian state of Queensland (QLD) is home to numerous unreinforced masonry (URM) buildings constructed more than 120 years ago. Many of these masonry structures hold heritage value and are significant cultural assets, leading to their inclusion in the Queensland Heritage Register. Understanding the structural vulnerabilities and challenges associated with these buildings is crucial for state authorities to formulate preservation strategies to protect their cultural assets. Although the QLD state is generally considered to have low seismic hazard when compared to other regions, its potential seismic risk is substantial due to the heightened vulnerability of its buildings. Therefore, prioritising seismic vulnerability assessments for these structures is essential to evaluate their present condition and implement necessary measures to prevent potential harm to the buildings and their occupants and avert economic losses. This study focuses on assessing QLD's old URM buildings constructed before 1940 using a methodology proposed in the literature to evaluate the seismic vulnerability of façade walls. Such a methodology relies on calculating a vulnerability index and employs a hybrid approach to generate damage and loss scenarios on a regional scale. A total of 363 URM buildings across seven towns of QLD were assessed using existing data gathered through field surveys. The findings are analysed and compared to previous vulnerability studies on similar building typologies in Australia and are presented through maps created using an open Geographical Information System (GIS) tool. The insights generated in this research can serve as a valuable resource for identifying critical buildings and proposing conservation or retrofitting plans. This study's findings indicate that many of the assessed buildings are potentially vulnerable to earthquakes of low to moderate intensities, necessitating, therefore, further investigation using more detailed tools. This screening will contribute to developing more appropriate and effective risk mitigation strategies.