Chapter A4 of the International Existing Building Code has played an important role in providing national model building code provisions to communities interested in improving seismic resistance of vulnerable soft-story wood-frame buildings. There are, however, many aspects of Chapter A4 that could be substantially improved to better serve the engineers and communities that rely on the document. Two important issues that need to be better addressed by these provisions include: 1) identification of vulnerable buildings, and 2) direction to design professionals regarding seismic strengthening design requirements. These subjects have also been addressed, directly or indirectly, by shake table testing, analytical studies, and building case studies from the CUREE-Caltech Woodframe Project, the NEESWood project, and others, which have provided further understanding of the contributions of various building materials to overall seismic resistance, the distribution of force and deformation demands in wood-frame buildings, and the implications of seismic strengthening. Drawing from research and analysis efforts, more direct methods to identify and strengthen vulnerable buildings are suggested.
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