Two-Story Residential Structure Damages after the 2020 Puerto Rico Earthquake

This paper reports an assessment of structure damages after the Richter magnitude 6.4 Puerto Rico earthquake that occurred on January 7, 2020. A review of the seismicity of the region and the postdisaster investigation of structural damages is first presented. The paper then focuses on explaining the failure modes of 2-story residential structures with open first story, which demonstrated the classical soft story behavior. The typological characterization of the failure modes is investigated using a nonlinear elastic dynamic analysis with a single degree of freedom model, which illustrates the contributions from partial to full construction of infill walls to the stiffness of the 2-story structures. The results indicate that the completion of the infill walls can significantly improve the stiffness of these structures and reduce damages to the structures.