Abstract

We evaluate the relative seismic risk between one- and two-story single-family houses, critically assessing the practice of lumping them into a single class for regional risk assessments. Two-story houses are more flexible and experience, on average, spectral displacements 4.7 times larger than those of one-story houses. Furthermore, two-story houses highly concentrate deformation demands on their first stories, resulting in story drifts 4.6 times larger than those in one-story houses. Therefore, two-story houses experience significantly higher damage, which is consistent with observations after different earthquakes. Results suggest that classification systems should be updated, separating one- and two-story houses into different categories.