Numerical Analysis on seismic retrofitting of a non-standard reinforced masonry house using cross-pattern ferrocement layers

Earthquakes frequently cause severe damage to non-engineered residential buildings in Indonesia, particularly reinforced masonry (RM) houses built with hollow brick walls lacking proper seismic detailing. These structures exhibit low tensile strength and brittle performance, making them vulnerable to lateral seismic loads. This study investigates the seismic behavior of a typical non-standard RM house and evaluates the effectiveness of a cross-system ferrocement strengthening technique in improving wall performance. A numerical model was developed in ETABS V.22 based on a real damaged house from the 2022 West Pasaman earthquake. Time-history analyses were performed using four peak ground acceleration (PGA) levels: 0.3 g, 0.6 g, 1.0 g, and 1.5 g. Results show that tensile stresses in unretrofitted walls consistently exceed the tensile capacity of hollow brick masonry, indicating a high probability of cracking and potential partial collapse. Conversely, the strengthened model demonstrated substantially reduced stresses, improved load distribution, and enhanced ductility due to the contribution of the ferrocement layer, where the wire mesh acts as tensile reinforcement. These findings confirm that the cross-system ferrocement method is a practical and effective retrofit solution to enhance seismic resilience and mitigate the collapse risk of existing RM houses in earthquake-prone communities.