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Seismic Engineering of Earthen Buildings
Serving California and the World Since 1984
Telephone: (510) 295-4299
Seismic Performance of Adobe Structures
the seismic performance of adobe buildings during his doctoral thesis.
understanding of how these building behaves but the solutions to improving
their behavior seemed simple to understand; the fundamentals of stabilizing an
of wood blocks.

Because of this innovative doctoral research, Dr. Tolles was selected by the
Getty Conservation Institute (GCI) to head their multi-year, multi-disciplinary
research effort to develop innovative methods for retrofitting historic adobe

In the first year of the project, Dr. Tolles headed the team that co-authored a
paper on the understanding the seismic performance of adobe buildings
which is available in PDF format at the following link:

Recent developments (PDF document)

The biggest single factor that makes adobe buildings unique is the thickness
of their walls. Thick walls are inherently difficult to de-stabilize and minor
measures can be used to stabilize the walls.
Video 1 at the left side of this
provides a discussion of the issues related to the out-of-plane
performance of adobe walls.
Video 2 provides a simulation of the collapse of
an adobe building by the small wood-block models. Video 2 also shows the
effect of strengthening the walls on the overall stability of a structure.

In his Ph.D. research, Dr. Tolles demonstrated that the simple coupling of
two load-bearing out-of-plane walls can greatly improve the out-of-plane
stability of these walls. The second model, Model 3, has the long walls
coupled by anchoring the roof beams to the walls. But, it should be noted that
there is no diaphragm at all. Even with the diaphragm with no strength or
stiffness, there is a significant impact on the stability of the two walls
because the two walls have different dynamic characteristics and are
working against each other that results in greater stability for both walls.

Video 3
shows the effectiveness of wall coupling in improving the
out-of-plane stability of adobe walls.
Video 1: Out-Of-Plane Adobe Masonry Analysis
Video 2: Collapse of an Unretrofitted (Wood-Block)
Adobe House Compared to a Retrofitted Model.
Video 3: A small-scale model of an adobe building
collapses easily but even minor wall coupling greatly