Seismic Engineering of Earthen Buildings Serving California and the World Since 1984
Telephone: (510) 295-4299
Doctoral Research & Thesis
writing of his doctoral thesis: SEISMIC STUDIES ON SMALL-SCALE Dr. Tolles spend over seven years doing the basic research, analysis and MODELS OF ADOBE HOUSES. The primary goals of this research were to evaluate the seismic performance of adobe buildings and determine the effectiveness of very simple seismic improvement measures.
The most common conceptual framework used to understand the seismic behavior of buildings during earthquakes is based on a static force equivalent to replicate dynamic earthquake forces. Based upon this conceptual framework, adobe buildings have little residual capacity once cracks have occurred and the buildings should collapse shortly after cracks have fully developed.
For thick-walled adobe buildings, nothing could be further from the truth. The interesting portion of an adobe buildings performance is only just beginning at the time when cracks have fully developed.
Adobe buildings have thicker walls that almost any other masonry building type. The walls typically have height-to-thickness (slenderness) ratios of 5 or 6 whereas common brick buildings have slenderness ratios of 10-15. A thin brick wall will overturn easily but it is much harder to de-stabilize a thick adobe wall and modest efforts to improve the out-of-plane stability can make dramatic improvements for the seismic behavior of these adobe buildings.
The focus of Dr. Tolles’ research was towards application to rural housing in developing countries. Since adobe buildings are most commonly used in areas were money is scarce, the retrofit measures needed to be simple and cost- effective but must also be structurally effective.