Fragility Curves for Low-Rise Residential Masonry Buildings in Low Seismicity Regions

Many low-rise residential masonry buildings were designed and constructed without seismic design criteria. Such buildings are generally safe under gravity loading unless uneven soil settlements take place under the building. Predicting the behavior of masonry structures under earthquake forces has always been complex due to their heterogeneity and brittleness. In recent years, seismic evaluation of masonry structures in the Groningen region has gained importance due to natural gas extraction that resulted in subsidence above the field. Using nonlinear incremental dynamic analysis (IDA) curves, it can be probabilistically understood whether the structure would meet the performance targets at various intensity levels. This paper focuses on a 19th century, 2-story unreinforced brick masonry (UBM) building in Groningen which reflects the general typology of the region. LS-DYNA has been used as an useful computational tool in the 3D structural modeling and analyses. IDA and fragility curves are evaluated according to the Dutch earthquake code (NPR 9998R + C1), TYDRYK (The Earthquake Risk Management Guide for Historic Buildings in Turkey) 2017, and Eurocode 8. Considering the five earthquake records (Huizinge) in each direction, it is seen that the collapse prevention criterion proposed by the regulations (0.8–1.0% drift) is exceeded. The developed fragility curves suggest that the probabilities for each code-based performance level vary significantly. For example, as per EC8, the level of collapse prevention is reached when the spectral acceleration coefficient is 3 for a probability of exceedance of 48%. For the same coefficient, a probability of exceedance of 28% is obtained when TYDRYK 2017 is used.