Cyclic testing of a full-size stabilised flax fibre reinforced earth (Uku) wall system with openings

Abstract

Uku is a low-cost earthen construction method that has been developed to address the inadequate housing situation in rural Māori communities resulting from legal, financial and physical obstacles. Rural Māori communities are often isolated and lack affordable access to specialist equipment, technical expertise, skilled labour and building materials. In addition to this, many rural communities are located in earthquake prone regions. A cyclic load test was conducted on a full-size 5.5 metre long wall section based on a wall line, built in an existing Uku test house, incorporating a window and door opening. The current seismic design proposed for the Uku housing system uses conservative assumptions due to the lack of data pertaining to the seismic performance of the wall system. The wall test was conducted in order to ascertain the methods of failure, areas of structural seismic weakness, interactions between wall panels, and the structural performance of the wall system. The results of the tests will be used to update the existing design methodology for Uku houses. The cyclic wall test has proven that the Uku wall system has a non-linear capacity but shown that the wall exhibits non-ductile modes of failure within each individual earth panel. The test has provided a foundation on which to develop an efficient, seismically safe design methodology for future Uku housing developments in New Zealand.