PROTOTYPE BASE-ISOLATED SINGLE FAMILY HOUSE

7045 CHABOT ROAD, OAKLAND, CALIFORNIA

DAMPED SWAY FOUNDATION SYSTEM©

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The foundation for the Langenbach House at 7045 Chabot Road in Oakland, California is a prototype example of a new type of foundation system designed to provide an economical means of reducing the potential destructive effects of earthquakes on residential structures.  Called the Damped Sway Foundation System © , this foundation system utilizes steel screw piles (helical anchors) instead of the usual concrete piers or grade beam.  These steel piles are allowed to sway in the event of an earthquake.  The dampers then stop the oscillations in the superstructure, thus dissipating the destructive energy of the earthquake on the vulnerable parts of the home.  The use of dampers has a similar effect as do shock absorbers in an automobile.

The use of the steel screw piles together with the steel first floor platform allows for the economical installation of a secure foundation system in soil conditions which require deep driven piles or piers.  This element allows for the elimination of the need for grade beams and other expensive site work.  The problem of the use of screw in seismic is that, if unrestrained, the shaking of the superstructure in an earthquake could be enhanced.   This amplification could damage the building and its contents.  The installation of the seismic dampers turns this problem into an asset by introducing damping of the energy before it can cause damage in the superstructure.

The Damped Sway Foundation System © will (1) significantly reduce the destructive effects of earthquakes on the superstructure and contents of small buildings such as homes and low-rise commercial structures by dissipating energy and lengthening the period of the shaking on the structure, (2) be economical to install, (3) potentially allow for the reduction in seismic strengthening measures which would otherwise be required for the superstructure of the buildings, (4) potentially make it earthquake insurance for the structure and its contents both more readily available and less expensive.

This foundation system was conceived, designed and developed by Randolph Langenbach, owner/builder, and Gene St. Onge, Engineer (Oakland, California).  The manufacturing and installation of the helical anchors, and the construction of the house was carried out by Pacific Housing Systems (Danville, California) with the interior plastering and concrete casting of the kitchen counters by Randolph Langenbach.  The consulting engineer for the damper manufacturer (Taylor Devices) was the late Roger Scholl. 

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© Randolph Langenbach

M-Arch (Harvard), Dipl.Conservation (York, England)

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