Abstract:In April 2014, the city of Moore, Oklahoma, adopted enhanced building codes designed for wind-resistant construction. This action came after Moore suffered three violent tornadoes in 14 yr. Insured loss data and a rigorous approach to estimating how much future damage can be mitigated is used to conduct a benefit–cost analysis of the Moore standards applied to the entire state of Oklahoma. The results show that the new codes easily pass the benefit–cost test for the state of Oklahoma by a factor of 3 to 1. Add… Show more
“…Mann et al, 2014;IPCC, 2014). For example, the implementation of tornado safe rooms or tornado shelters and adaption of building codes may enhance tornado survivability and decrease disaster consequences in tornado-prone areas (Simmons and Sutter, 2007;Prevatt et al, 2012;Simmons et al, 2015). Restricting new development near uncertain and dynamic floodplains (Patterson and Doyle, 2009), seismically and volcanically active areas (Strader et al, 2015b), locations prone to wildfires (Bryant and Westerling, 2014;Mann et al, 2014), regions subject to tropical cyclone hazards and sea-level rise (Pielke et al, 2008;Maloney and Preston, 2014) may reduce disaster losses.…”
Section: Conclusion and Discussion Of Future Improvementsmentioning
ABSTRACT:Determining the likelihood and severity of tornado disasters requires an understanding of the dynamic relationship between tornado risk and vulnerability. As population increases in the future, it is likely that tornado disaster frequency and magnitude will amplify. This study presents the Tornado Impact Monte Carlo (TorMC) model, which simulates tornado events atop a user-defined spatial domain to estimate the possible impact on people, the built-environment or other potentially vulnerable assets. Using a Monte Carlo approach, the model employs a variety of sampling techniques on observed tornado data to provide greater insight into the tornado disaster potential for a location. Simulations based on 10 000 years of significant tornado events for the relatively high-risk states of Alabama, Illinois and Oklahoma are conducted to demonstrate the model processes, and its reliability and applicability. These simulations are combined with a fine-scale (100 m), residential built-environment cost surface to illustrate the probability of housing unit impact thresholds for a contemporary year. Sample results demonstrate the ability of the model to depict successfully tornado risk, residential built-environment exposure and the probability of disaster. Additional outcomes emphasize the importance of developing versatile tools that capture better the tornado risk and vulnerability attributes in order to provide precise estimates of disaster potential. Such tools can provide emergency managers, planners, insurers and decision makers a means to advance mitigation, resilience and sustainability strategies.
“…Mann et al, 2014;IPCC, 2014). For example, the implementation of tornado safe rooms or tornado shelters and adaption of building codes may enhance tornado survivability and decrease disaster consequences in tornado-prone areas (Simmons and Sutter, 2007;Prevatt et al, 2012;Simmons et al, 2015). Restricting new development near uncertain and dynamic floodplains (Patterson and Doyle, 2009), seismically and volcanically active areas (Strader et al, 2015b), locations prone to wildfires (Bryant and Westerling, 2014;Mann et al, 2014), regions subject to tropical cyclone hazards and sea-level rise (Pielke et al, 2008;Maloney and Preston, 2014) may reduce disaster losses.…”
Section: Conclusion and Discussion Of Future Improvementsmentioning
ABSTRACT:Determining the likelihood and severity of tornado disasters requires an understanding of the dynamic relationship between tornado risk and vulnerability. As population increases in the future, it is likely that tornado disaster frequency and magnitude will amplify. This study presents the Tornado Impact Monte Carlo (TorMC) model, which simulates tornado events atop a user-defined spatial domain to estimate the possible impact on people, the built-environment or other potentially vulnerable assets. Using a Monte Carlo approach, the model employs a variety of sampling techniques on observed tornado data to provide greater insight into the tornado disaster potential for a location. Simulations based on 10 000 years of significant tornado events for the relatively high-risk states of Alabama, Illinois and Oklahoma are conducted to demonstrate the model processes, and its reliability and applicability. These simulations are combined with a fine-scale (100 m), residential built-environment cost surface to illustrate the probability of housing unit impact thresholds for a contemporary year. Sample results demonstrate the ability of the model to depict successfully tornado risk, residential built-environment exposure and the probability of disaster. Additional outcomes emphasize the importance of developing versatile tools that capture better the tornado risk and vulnerability attributes in order to provide precise estimates of disaster potential. Such tools can provide emergency managers, planners, insurers and decision makers a means to advance mitigation, resilience and sustainability strategies.
“…The code increased the wind standard for new dwellings from 90 mph (three‐second gust) to 135 mph, which required a series of changes in how wood frame homes are constructed, including: Enhanced roof sheathing fasteners and fastener schedules, narrower spacing of the roof framing, enhanced connections in the roof framing including the use of hurricane straps, strengthening of gable end walls and wall sheathing, some structural changes to garages, and wind‐rated garage doors . (Simmons et al., )…”
Section: Tornadoes and Enhanced Building Codes In Oklahomamentioning
confidence: 99%
“…Enhanced roof sheathing fasteners and fastener schedules, narrower spacing of the roof framing, enhanced connections in the roof framing including the use of hurricane straps, strengthening of gable end walls and wall sheathing, some structural changes to garages, and wind‐rated garage doors . (Simmons et al., )…”
Section: Tornadoes and Enhanced Building Codes In Oklahomamentioning
confidence: 99%
“…This study addresses these questions by exploring homeowner support for relatively simple and inexpensive (∼$2,000 per home) building code enhancements that are estimated to reduce tornado losses by 30% or more (Simmons, Kovacs, & Kopp, ). We focus on the U.S. state of Oklahoma, which experiences more than 65 tornadoes per year that impose significant costs on homeowners (Storm Prediction Center, ).…”
Tornadoes impose enormous costs on society. Relatively simple and inexpensive enhancements to building codes may reduce these costs by 30% or more, but only one city in the United States has adopted these codes. Why is this the case? This analysis addresses this question by examining homeowner support for more stringent building codes in Oklahoma, a conservative state that routinely experiences damaging tornadoes. Survey data show that support for mandatory mitigation policies like building codes is subject to countervailing forces. Push dynamics, including objective risk data, homeowners' risk perceptions, and damage experience, encourage support for mitigation. Pull dynamics, such as individualistic and conservative worldviews, and skepticism about climate change, generate opposition. At the margin, the pull dynamics appear to exert more force than push dynamics, creating only a weak basis of support that is not strong enough to overcome the status quo bias in a state that is cautious about regulatory measures. The concluding section offers suggestions for changing these dynamics.
Wood-frame residential roof failures are among the most common and expensive types of wind damage. Hip roofs are commonly understood to be more resilient during extreme wind in relation to gable roofs. However, inspection of damage survey data from recent tornadoes has revealed a previously unstudied failure mode in which hip roofs suffer partial failure of the framing structure. In the current study, evidence of partial framing failures and statistics of their occurrence are explored and discussed, while the common roof design and construction practice are reviewed. Two-dimensional finite element models are developed to estimate the element-level load effects on hip roof trusses and stick-frame components. The likelihood of failure in each member is defined based on relative demand-to-capacity ratios. Trussed and stick-frame structures are compared to assess the relative performance of the two types of construction. The present analyses verify the common understanding that toenailed roof-to-wall connections are likely to be the most vulnerable elements in the structure of a wood-frame hip roof. However, the results also indicate that certain framing members and connections display significant vulnerability under the same wind uplift, and the possibility of framing failure is not to be discounted. Furthermore, in the case where the roof-to-wall connection uses hurricane straps, certain framing members and joints become the likely points of failure initiation. The analysis results and damage survey observations are used to expand the understanding of wood-frame residential roof failures, as they relate to the Enhanced Fujita Scale and provide assessment of potential gaps in residential design codes.
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