Numerical investigation of seismic response of masonry structure strengthened with polyurea coating considering soil-structure interaction by distinct element method

Unreinforced masonry structures (URM) have been widely used for residential accommodations and public buildings for centuries. However, these structures are highly susceptible to damage under seismic loading because of their brittle characteristics and poor integrity. Applying composite coatings on masonry surfaces has become a common practice to improve the loading capacity of URM. This research evaluates the seismic response of URM with and without polyurea coating strengthening in several strengthening configurations through a series of rigorous time-history analyses conducted on a masonry structure using the distinct element method (DEM). The validation results of this research against previous testing data show that with reasonably sophisticated material models, DEM can accurately capture the structural response of masonry structures with realistic deformable shapes and progressive collapse. In addition, coating the entire exterior of the masonry structure with polyurea can significantly increase the deformation capacity of the structure, enabling the structure to withstand higher excitation motion intensity. Moreover, the effect of soil–structure interaction (SSI) is also included in this study. Ground surface rocking and spatially varying vertical accelerations appearing in the SSI model easily deteriorate the seismic performance of this irregularly shaped masonry structure, leading to collapse under very low input excitation intensities.