Federal Emergency Management Agency

Seismic Evaluation and Retrofit of Multi-Unit Wood-Frame Buildings With Weak First Stories

Main Content
Cover photo for the document: Seismic Evaluation and Retrofit of Multi-Unit Wood-Frame Buildings With Weak First Stories
Multi-unit wood-frame buildings with a weak first story represent a significant risk in highly seismic regions of the United States because of their high potential for collapse. This collapse potential is due primarily to their soft or weak first-story walls, which have often been weakened by large numbers of openings such as garages or store front windows.  FEMA P-807 addresses seismic retrofitting of weak-story wood-frame buildings in seismically active regions of the United States, with a focus on multi-family, multi-story buildings with weak first stories, and apartment buildings with tuck-under parking. These seismic retrofitting guidelines are the first to focus solely on the weak first story and to provide just enough additional strength to protect the first floor from collapse but not so much as to drive earthquake forces into the upper stories, placing them at risk of collapse. They are also the first to take into account the strength provided by existing non-structural walls, making seismic retrofitting more affordable. An electronic tool was developed as part of the project to help apply the rules and perform the calculations described in the report. The Weak Story Tool (WST) is available for download as a zip file. Note that the report contains all the data, formulas, and procedural background needed to apply the method without using the WST.
SizePublication Date
CD-ROM (with PDF, WST, and appendices) attached to back cover
May 1, 2012
Icon for file of type text/plainSeismic Evaluation and Retrofit of Multi-Unit Wood-Frame Buildings With Weak First Stories
568.89KMay 1, 2012
Icon for file of type application/pdfSeismic Evaluation and Retrofit of Multi-Unit Wood-Frame Buildings With Weak First Stories
11.34MMay 1, 2012
Icon for file of type application/zipWeak Story Tool (WST) zip file
1.78MMay 1, 2012
Back to Top