Seismic Vulnerability Assessment of Mixed Masonry-RC Residential Buildings

Abstract

The practice of unreinforced masonry has been around since ages. In seismically active zones like Nepal, it is utmost for the structures to be designed by following proper seismic design criteria. However, the majority of older unreinforced buildings in Nepal are non-engineered or semi-engineered constructions with inadequate seismic detailing. A detailed visual assessment of the Panauti municipality area, led to the identification of a unique building typology. The term “mixed Masonry-RC” represents the typology with one or two centrally located reinforced concrete columns supporting concrete slabs and beams spanning along the grid of columns which altogether rest over peripheral load bearing unreinforced brick masonry in cement mortar. A total of five building models were taken which belonged to this typology. The buildings were modelled in SAP2000 and pushover analysis was performed. This was followed by generation of fragility curves under different Peak Ground Accelerations (PGAs) of response spectra in NBC 105:2020. The fragility curves thus obtained were used to understand the vulnerability of the structure to considered earthquakes. This study can be further extended for the seismic assessment of similar typology buildings and for appropriate recommendation of strengthening measures.