Lisa Holliday

Building with Compressed Earth Block within the Building Code

AbstractDespite the use of earthen materials in building construction for thousands of years, many engineering properties of earthen walls are not well understood, documented, or regulated. California and New Mexico have adopted building codes allowing earthen structures through prescriptive methods that rely on rules of thumb to limit heights and spans of construction. Furthermore, California restricts earthen structures to very limited areas on the basis of soil type. Overall, the prescriptive methods have led to uncertainty about reinforcing requirements. There is a belief among builders who use earthen materials that reinforcement is required only in areas of high earthquake hazard, implying that a geographic area is either seismic or not. In reality, all locations are prone to some seismicity. On the basis of the probability of seismic activity and soil conditions at each locale, every site has a risk that ranges from very low to very high probability of earthquake damage. Energy compliance and struc...

Taquezal Buildings in Nicaragua and Their Earthquake Performance

AbstractTaquezal is a common earthen building type in Nicaragua. It is constructed by building a wood frame and then packing the frame with mud to create thick earthen walls. The wood frame allows the structure to be constructed without the formwork (which is required for rammed earth buildings) and without first constructing blocks (which is generally required in adobe construction). The wood frame also allows a thinner wall than other earthen building types. Commonly, taquezal roofs are made of timber framing and heavy clay tile roofs. Taquezal buildings are not engineered and therefore are difficult to analyze with modern structural engineering methods. During the 1972 Managua earthquake, nearly 10,000 people died, and most of them were in taquezal buildings. This paper discusses taquezal as a structural system and applies engineering methods to this nonengineered structure. It was found that taquezal buildings perform well during low-to-moderate earthquakes if well maintained. However, if the wood is ...

Performance of Enhanced Residential Building Code Requirements during the March 25, 2015, Moore Tornado

AbstractAn EF2 (Enhanced Fujita Scale Rating 2) tornado that hit the City of Moore, Oklahoma, on March 25, 2015, provided a rare opportunity for engineers to observe the performance of structures b...

Collapse of a historic adobe wall

Abstract The city of Leon, Nicaragua is a stunning example of Spanish colonial architecture. The historic buildings of Leon were built using adobe construction, which was typical of the nineteenth and early twentieth century, and the city is working hard to preserve their historical architectural heritage. Unfortunately, the Office of Historic Preservation in the town of Leon, Nicaragua received a call that an adobe wall had collapsed. Fortunately no one was injured, but this was not an ordinary wall. The city of Leon lost a portion of an important historic structure. The historic adobe building was being carefully remodelled. The walls were to remain intact while the inside structure was removed and replaced with a new structure. The guidelines instructed them to leave 70 cm of foundation next to the adobe walls while excavating the basement. This was not sufficient and the weight of the wall caused a breach in the basement portion of the wall and the wall collapsed by sliding out like an avalanche. This paper examines the cause of the failure and recommends better construction methods to preserve historic adobe walls such as the one in Leon, Nicaragua.

Low-Cost Earthquake Solutions for Nonengineered Residential Construction in Developing Regions

AbstractLow-rise concrete and masonry structures can provide excellent seismic resistance when they are designed by an engineer, are made of quality materials, and are built by well-trained workers in conformance with building codes. Unfortunately, this is not the way many of the structures are being built in developing regions. Property owners themselves are building low-rise nonengineered structures, paying little attention to building codes or seismic resistance. Adding to the problem, when building with concrete and masonry construction, it is possible to have relatively long spans, large openings, and irregular shapes, all of which impact their earthquake performance. These nonengineered buildings are deceptive because they seem safe, they perform well under gravity loads, and they do not sag or lean. In this study, several typical concrete and masonry low-rise residential buildings were modeled and subjected to seismic loads. These models were then manipulated to determine which low-cost changes wil...