Abstract Summary
Informal construction comprises 50% to 90% of residential construction in low and middle-income countries. A significant amount of these buildings is constructed in masonry infilled reinforced concrete (RC) frames, without engineering oversight and the license required for the construction. They are often built by residents or builders who may not have formal construction training and thus do not comply with regulations or design codes. This type of construction is prone to high levels of variability in the material properties, posing a significant challenge in their seismic performance evaluation. This study presents a framework to evaluate the seismic fragility of informally constructed masonry infilled RC frame buildings that accounts for the variability in the materials. The framework consists of four stages. The first one is a statistical characterization of material properties typically used in the construction process by builders. The second stage involved inelastic modeling of the structure capable of capturing the performance of concrete elements and masonry walls. A parametric analysis is proposed in the third stage using Monte Carlo simulations that integrate the first and the second stages to capture the variability of material properties. The fourth stage consists of a performance assessment represented in a probability distribution for each engineering demand parameter (EDP) considered in the study. This framework is demonstrated using an informal house representative of the informal construction in Sincelejo. This is a municipality located on the north coast of Colombia, and according to the national census, 35% of the dwellings in its urban area are built with inappropriate materials. Fieldwork conducted as part of this study suggests that this percentage may be higher. The results showed that the framework allows capturing the uncertainty in the materials construction variability of informal houses. The results also showed that using mean values of material properties may lead to significant errors in the seismic performance assessment of informally constructed masonry infilled RC frames, with estimations of the probabilities of exceeding damage limits that may deviate more than 80% of the median values.
