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the Ventura County Department of Building and Safety repair and seismic retrofitting.
to ensure that the design conformed to the U.S. Visible is a horizontal steel cable
Secretary of Interior Standards for restoration of with cable ties, and a stress
historic properties, and was in compliance with the distributing end plate.
safety requirements of existing building codes. Photo: William S. Ginell.

The design of the retrofit project was based largely upon the results of the GSAP research.
Indeed, this effort involving an existing earthquake-damaged adobe building was the
initial application of the principles and techniques that were studied and experimentally
validated at the GCI. Because the techniques and technology were innovative and had not
been previously implemented, a careful review of the proposed retrofit measures was
carried out.

These measures included horizontal cables around
perimeter walls which, in some areas, were anchored to
ceiling joists; vertical cables or straps on both sides of
adobe walls that were either too thin or particularly
vulnerable due to damage from past earthquakes;
vertical center-core rods that were placed in newly
constructed walls; and anchorage at the floor levels. To
our knowledge, this was the first time that pretensioned,
vertical stainless steel cables recessed into walls had
been used on an adobe structure (they had been
previously used to reinforce stone walls for which the
height-to-thickness ratio was greater than eight).

This first implementation of the GSAP research results
required some redesign of laboratory-tested details for
application to real-world conditions. It also required
acceptance by building officials and by the California
Office of Historic Preservation, as well as input and
review by the building owners, who were particularly
concerned about safety in and around their building. The
seismic retrofit and repair of the main building have A vertical steel cable recessed
been completed, and it is anticipated that repair of the into an exterior wall. The cable
winery will be carried out in the near future. will be prestressed, then covered
with adobe mortar.
Detailed information on the Institute's research into Photo: William S. Ginell.
seismic strengthening—and on the retrofitting
recommendations growing out of that research—will be available in two forthcoming
publications from the GCI. The first, GSAP Final Report, will provide a comprehensive
description of six small-scale and two large-scale tests conducted to determine the
effectiveness of several retrofitting techniques. The second, Planning and Engineering
Guidelines for Seismic Retrofitting of Adobe Buildings, will offer specific recommendations
on how to fortify historic adobes against seismic destruction in a manner that preserves
the integrity and authenticity of this important part of our heritage.

William S. Ginell is a senior conservation scientist
with the GCI, and project director of GSAP. E.
Leroy Tolles served as the principal investigator
of GSAP.

A detail of a steel cable and nylon
tie.
Photo: William S. Ginell.