Date of Award
Santa Clara : Santa Clara University, 2018.
Earthen construction is the most popular building method around the world. One particular building method, using earthbags, has shown promise in performing well against seismic activity. This project undertook the goal of developing a preliminary seismic response modification factor, R, to be used in the design of homes in seismically active areas. Two 4’ wide x 6’ tall x 1’ deep walls were cyclically loaded using a Three-Degree-of-Freedom (TDOF) Test Frame provided by Santa Clara University to determine the in-plane shear capacity of each wall. Testing revealed an average yield force of 419 lbs, an average ultimate force 1058 lbs, and an average R value of 6.
Wall design and construction was focused on three aspects of the project that were modeled to replicate common building practices while still being modular enough to test multiple samples. These aspects were the base, bond beam, and wall. Wall bases were designed to withstand up to 3500 lb-ft bending moment during forklift transport, the bond beam was designed to transfer up to 9,000 lbs of shear force into the wall, and, the wall was designed using common building practices used in earthbag construction.
Upon completion of the Consortium of Universities for the Research of Earthquake Engineering (CUREE) testing protocol, it was observed that the walls failed in buckling due to compression resulting from the force couple created by the loading arrangement. Despite failure, the walls continued standing even after the pin connection was removed from the tops of wall. This unexpected resiliency and behavior of the walls during testing led the team to believe that earthbag walls are much more ductile a material that was initially anticipated. A deeper understanding is needed to better understand how earthbag buildings behave against seismic forces. This project is encouraging for future research and the development of a more standardized building method.
Rodriguez, David Aguilar; Stein, Jeff; and Darby, Taylor, "Cyclic Testing of Reinforced Earthbag Walls" (2018). Civil, Environmental and Sustainable Engineering Senior Theses. 68.