September 12, 2005
HOMEOWNERS TOLD TO ANCHOR-BOLT THEIR HOMES TO THE FOUNDATIONS AS FIRST STEP IN EARTHQUAKE PREPAREDNESS
New Handbook Offers Vital Tips to Bay Region Residents
September 12, 2005 - San Francisco - In a new handbook just released in the San Francisco Bay Area, structural engineers warn homeowners and other property dwellers that the first defense against future earthquakes is to adequately anchor or bolt the foundation.
Houses that are not adequately anchored or bolted to the foundation have the potential to slide off the foundation during an earthquake, severely damaging or destroying the building, said Reinhard Ludke, a structural engineer with Creegan + D'Angelo, a member of the Structural Engineers Association of Northern California and one of the authors of the new handbook, "Putting Down Roots in Earthquake Country - Your Handbook for the Bay Region."
The handbook is a joint project of several Bay Area groups including the USGS, American Red Cross, California Earthquake Authority and SEAONC. The goal of the 32-page booklet is to educate Bay Area citizens about the likely impact of future earthquakes and to motivate them to take simple steps now to make their families, homes, schools and workplaces safer before the next quake or other disaster strikes.
Fewer than 10% of homeowners in the Bay Area have taken the necessary simple steps to retrofit their homes, Ludke explained, which will translate into a dramatic loss of dwellings following a major earthquake. Total Bay Area losses in a major quake could be larger in scale than the Gulf Coast devastation caused by Hurricane Katrina earlier this year, where tens of thousands of homes were destroyed by the winds and floods, he said.
In the booklet, which is available online and downloadable at http://pubs.usgs.gov/gip/2005/15/, homeowners are told they also need to check for another deficiency in the foundation called an unbraced "cripple wall." This is the short wall that connects the foundation to the floor of the house and encloses the home's crawl space. These walls need to be braced with plywood. Otherwise, they have the potential to "tip" over, and cause the house to collapse onto the foundation.
The good news is that the basic earthquake problems in a house, both structural and nonstructural, can be reduced through easy and inexpensive means, noted Ludke.
Nonstructural deficiencies such as un-braced water heaters, masonry chimneys, tall shelves and tall file cabinets can usually be mitigated (or protected against failing during an earthquake) with the use of simple metal clips and straps bought at a local hardware store. Not only can these elements cause damage to the property if not properly secured, they could also topple over and cause severe injury to individuals.
Checking for structural deficiencies, such as unbolted foundations and cripple wall, will probably require the hiring of a structural engineer or general contractor.
Founded in 1930, the Structural Engineers Association of Northern California (SEAONC) is committed to the advancement and incorporation of the state of the art in structural engineering standards and practices through applied research, continuing education, and the promotion of professional relations among Civil, Structural, and Geotechnical Engineers.
Contact: Patricia Coate 415-309-2231