Tornado-Resistant Residential Design Using Experimentally Obtained Characteristic Strength Values for Cement-Stabilized Earthen Masonry

Abstract

Compressed and stabilized earthen masonry (CSEM) offers a sustainable, affordable, and locally appropriate alternative to traditional residential construction. It provides a method that can enable the community to solve their own housing needs instead of aiding them just one time. While a significant amount of work has recently been done to engineer earthen masonry systems, research gaps remain. To address some of these research gaps, the goals of this paper include understanding the capacity of unreinforced and reinforced CSEM walls against extreme wind loads and developing a systematic approach to the schematic design of residential structures with safe rooms utilizing a combination of empirical data, statistical analysis, and available codes and standards. For this purpose, experimentally obtained compressive strength data for compressed and 10% cement-stabilized earth blocks, soil-based mortars, and CSEM assemblies are statistically analyzed. The test data are then benchmarked to a similar study with concrete masonry units and traditional mortars to understand the relative level of variability of CSEM assemblies and interactions of units and mortar in each type of masonry. After such analysis, the CSEM characteristic strength is computed statistically, following TMS 602 (specification for masonry structures) criteria for concrete and clay masonry. The characteristic strength is then used in the design of a conceptual single-family dwelling with a tornado-resistant safe room, assumed to be located in Winnebago, Nebraska. The site selection has a significance in that the Indian reservation in Winnebago is a plausible location for this technology’s future adoption due to their acute housing needs and the habitants’ open-minded approach to sustainable building design. The study’s findings indicate that with a proper recipe for the local soils, a good workmanship of CSEM components, and a careful design of the CSEM walls and connections, this technology can be utilized in a residence located in an area subject to tornadoes.