Evaluation of the seismic performance in confined masonry dwellings retrofitted with steel mesh and cement-sand mortar

Resumen

This research is based on field studies conducted by CISMID - FIC – UNI, where in 2019 determined that 83% of dwellings in the Metropolitan Lima area are constructed with masonry. A significant portion of these are non-engineered dwellings, built without professional supervision or quality control of materials, making them highly vulnerable to seismic events. The study examines the seismic vulnerability of fourteen types of non-engineered masonry dwellings in Metropolitan Lima area, each with five different wall densities. The research begins with a review of related studies and the theoretical framework on the non-linear behavior of non-engineered confined masonry walls, both with and without retrofitting. Seismic records for rigid soil (S1) and intermediate soil (S2) were amplified for six seismic demands accordant with ASCE-41-13 and the E.030 Peruvian National Earthquake Resistant Standard. Capacity curves for confined masonry dwellings, both retrofitted and non-retrofitted, were calculated using formulations proposed by related studies. The results showed that retrofitted dwellings exhibited increased shear resistance and lateral deformation capacity. Damage indices were defined to normalize drift, transforming this response into a scale from 0 to 5, facilitating the identification of the most damaged floors in dwellings with different non-linear behaviors in their stories. A total of 5880 nonlinear time history simulations were performed. The main results indicate that the non-engineered masonry dwellings studied lack sufficient capacity to resist severe seismic demand, particularly the rare seismic events expected in Lima due to seismic silence. However, the proposed retrofitting significantly reduces damage levels, preventing material and human losses.