Insurance Institute for Business and Home Safety

Richburg, United States

Insurance Institute for Business and Home Safety

Richburg, United States
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Standohar-Alfano C.D.,Insurance Institute for Business and Home Safety | Van De Lindt J.W.,Colorado State University | Ellingwood B.R.,Colorado State University
Journal of Structural Engineering (United States) | Year: 2017

Since the devastating 2011 tornado season, there has been renewed interest in understanding tornado wind loads and developing methodologies to reduce the risk of tornado damage. This study focuses on the assessment of the system-level performance of five different residential light-frame wood building archetypes subjected to tornado winds. The system-level performance considered three critical components along the vertical load path within each building, namely, the roof sheathing, roof-to-wall connection, and wall-to-foundation anchorage. Although there has been significant work on each of these components independently, combined uplift and lateral forces have received less attention. Therefore, a laboratory testing program for wood shear walls, reported herein, was performed to determine the wall-failure mechanisms and capacities when subjected to combined shear and uplift forces. Each building archetype was designed at varying locations across the United States based on the current residential building code and/or observed practice. Fragilities were developed, based on the assumption that failure of any component along the vertical load path results in failure of the system. Because the forces in each connection along the vertical load path arise from the same tornado wind load, the connection failures are not statistically independent, and Monte Carlo simulation was applied to perform the system reliability analysis. © 2017 American Society of Civil Engineers.

Giammanco I.M.,Insurance Institute for Business and Home Safety | Schroeder J.L.,Texas Tech University
12th Americas Conference on Wind Engineering 2013, ACWE 2013: Wind Effects on Structures, Communities, and Energy Generation | Year: 2013

The development and deployment of Texas Tech University's StickNet adaptive observing network has yielded an increased number of observations from the immediate shoreline [1]. The current study leverages research grade wind measurements from 6 different landfalling tropical cyclones from 2008-2012. Twenty-four individual deployments were made along the immediate shoreline resulting in over 1500 ten-minute data segments from onshore marine exposure regimes. The number of available data segments allowed for the wind flow characteristics to be examined as well as their dependence upon changing mean wind speed. Gust factors were found to be quite similar to overland open and smooth terrain exposures while roughness lengths and drag coefficient values approached those observed in deep water conditions [2][3].

Dixon C.R.,University of Florida | Masters F.J.,University of Florida | Prevatt D.O.,University of Florida | Gurley K.R.,University of Florida | And 3 more authors.
Journal of Wind Engineering and Industrial Aerodynamics | Year: 2014

This paper addresses the wind-induced tearing and blow-off of asphalt roofing shingles, which are the most frequently observed forms of residential building damage in hurricanes. Field surveys indicate that in-service asphalt shingle sealant strips can lose adhesion along their leading edge over time, leaving the shingle partially unsealed and susceptible to wind uplift. Two interrelated studies presented in this paper show that unsealing is a naturally occurring process and that unsealed shingles are a contributing cause of shingle roof cover damage in high winds. The first study quantified the number, location, and failure mode of laminate and three-tab style shingle systems installed on residential buildings at 30 sites in Florida and Texas. Systematic patterns of partially unsealed field shingles found on 22 of the 30 roofs resembled spatial patterns of wind-induced shingle damage observed in post-hurricane building performance assessments. As expected, older roofs generally contained more unsealed shingles than newer roofs. The results of the second study link blow-off to partially unsealed shingles. Seventeen ASTM D7158 Class H asphalt shingle roofs were aged outside for nominally one year at the Insurance Institute for Business & Home Safety Research Center and then evaluated in full-scale wind tunnel tests. Partially unsealed field and hip shingles frequently exhibited damage during wind testing, while fully sealed shingles were not damaged unless adjacent, unsealed shingles failed first. © 2014.

Bahrani B.,University of North Carolina at Charlotte | Zhou A.,University of North Carolina at Charlotte | Quarles S.L.,Insurance Institute for Business and Home Safety
International SAMPE Technical Conference | Year: 2016

Fire retardant coatings have been an important part of passive fire protection system for protecting structures in wildland urban interface (WUI) fires. However, limited studies have been conducted on their effectiveness and performance after long-term weathering exposure. This paper presents a study on the effects of weathering on the performance of intumescent fire-retardant coatings on wooden structures in the WUI. The main concerns of weathering effects are: 1) the reduction of ignition resistance of the coating layer after weathering; and 2) the fire properties of coatings after weathering as the coatings might contribute as a combustible fuel and assist the fire growth after ignition. The study evaluated three intumescent coatings which exposed to natural weathering conditions in three time intervals. More than 190 combustibility tests consisted of a bench-scale performance evaluation using a cone calorimeter were performed, and three radiative heat flux levels were used for each coating type and weathering period. The key findings for each coating type under different test conditions are discussed, and the performance evaluation criteria for the combustibility tests is presented. Copyright 2016. Used by the Society of the Advancement of Material and Process Engineering with permission.

Cope A.D.,Insurance Institute for Business and Home Safety | Crandell J.H.,ARES Consulting | Liu Z.,Insurance Institute for Business and Home Safety | Stevig L.J.,State Farm Mutual Automobile Insurance Company
Journal of Wind Engineering and Industrial Aerodynamics | Year: 2014

Recent full-scale studies of wind loads on components of multi-layer wall systems have shown that maximum instantaneous pressure differences across individual layers can be a large fraction of the net load across the wall system, as noted in Cope et al. (2012) The results of these studies are considerably different from results obtained using dynamic pressure chambers where the entire section of the wall is exposed to the same quasi-steady pressure difference or time varying pressures. The largest differences in results between the full-scale wind tests at the Insurance Institute for Business & Home Safety (IBHS) Research Center and the pressure chamber tests occurred for the exterior flexible multi-part siding layer. In the pressure chamber tests, the pressures tend to equalize rapidly between the exterior and interior surfaces of the flexible siding resulting in very low net loads on the siding. In the full-scale wind tests, the response of the flexible siding to the temporal and spatial variations in wind loads imposed by the flow around the building could be observed as a wave moving along the wall surface.The study reported in this paper investigates the loads on the fasteners used to attach the siding to the wall. Specifically, the relationship between the instantaneous pressure differences across the siding and the loads on the fasteners is presented; with the goal of determining whether any systematic reduction or amplification of loads on the fasteners resulted from the very short duration peak instantaneous pressure differences applied to the siding. Specialty instrumentation was developed that allowed measurement of outward acting loads applied to the siding fasteners. This paper describes that specialty instrumentation and presents comparisons of pressure differences multiplied by the tributary area assigned to a fastener against the withdrawal loads measured using the instrumented fasteners.While there is significant scatter in the results, probably due to friction in the fastener load system among other things, results show a strong overall one to one correlation between the net outward loads calculated by applying the pressure load to the tributary area and the measured loads on the fasteners. © 2014 Elsevier Ltd.

Brown T.M.,Insurance Institute for Business and Home Safety | Pogorzelski W.H.,Insurance Institute for Business and Home Safety | Giammanco I.M.,Insurance Institute for Business and Home Safety
Weather, Climate, and Society | Year: 2015

A series of thunderstorms on 24 May 2011 produced significant hail in the Dallas-Fort Worth (DFW) metroplex, resulting in an estimated $876.8 million (U.S. dollars) in insured losses to property and automobiles, according to the Texas Department of Insurance. Insurance claims and policy-in-force data were obtained from five insurance companies for more than 67 000 residential properties located in 20 ZIP codes. The methodology for selecting the 20 ZIP codes is described. This study evaluates roofing material type with regard to resiliency to hailstone impacts and relative damage costs associated with roofing systems versus wall systems. A comparison of Weather Surveillance Radar-1988 Doppler (WSR-88D) radar-estimated hail sizes and damage levels seen in the claims data is made. Recommendations for improved data collection and quality of insurance claims data, as well as guidance for future property insurance claims studies, are summarized. Studies such as these allow insurance underwriters and claims adjusters to better evaluate the relative performance and vulnerability of various roofing systems and other building components as a function of hail size. They also highlight the abilities and limitations of utilizing radar horizontal reflectivity-based hail sizes, local storm reports, and Storm Data for claims processing. Large studies of this kind may be able to provide guidance to consumers, designers, and contractors concerning building product selections for improved resiliency to hailstorms, and give a glimpse into how product performance varies with storm exposure. Reducing hail losses would reduce the financial burden on property owners and insurers and reduce the amount of building materials being disposed of after storms. © 2015 American Meteorological Society.

Henderson D.J.,University of Western Ontario | Henderson D.J.,James Cook University | Morrison M.J.,University of Western Ontario | Morrison M.J.,Insurance Institute for Business and Home Safety | Kopp G.A.,University of Western Ontario
Engineering Structures | Year: 2013

A full-scale, timber-framed, truss, hip roof was subjected to simulated wind loads. Spatially and temporally varying pressures were applied using an array of 58 Pressure Loading Actuators, together with air-boxes covering all roof surfaces. Load cells were incorporated at the top of the wall frame, just below the top plate, to measure the reactions at the toe-nailed roof-to-wall connections. Changes in influence functions and load sharing between adjacent trusses were observed to occur during withdrawal (slip) of the toe-nail connections caused by large magnitude, short duration peak pressures. Even for relatively small displacements, it was observed that the effective tributary area is substantially increased by the incremental withdrawals. This acts to increase the resilience of the roof by allowing more limber and/or more highly loaded connections to transfer loads to stiffer and/or less highly loaded connections. Influence functions, measured both prior to and following damage, were able to predict this behaviour. © 2013 Elsevier Ltd.

Morrison M.J.,Insurance Institute for Business and Home Safety | Cope A.D.,Insurance Institute for Business and Home Safety
Structures Congress 2015 - Proceedings of the 2015 Structures Congress | Year: 2015

Wind loads on different layers of a multi-layer wall assembly were determined under realistic loading conditions in the IBHS test chamber. The current results indicated the PEF of 0.36 currently used in the ASTM D3679-13 for vinyl siding is likely too low and a more suitable PEF would be in the range of 0.4 to 0.7, with an optimal value likely between 0.55 and 0.6. In contrast, the results from the present study on foam backed vinyl siding indicated that the PEF in ASTM D7445-09 of 0.7 are too high and may be overly conservative. The current results indicate most PEF values for foam backed vinyl fall between 0.2 and 0.55.

Brown T.M.,Insurance Institute for Business and Home Safety | Brown T.M.,Texas Tech University | Liang D.,Texas Tech University | Womble J.A.,Texas Tech University | Womble J.A.,WindForce Inc.
Wind and Structures, An International Journal | Year: 2012

Researchers have recently begun using high spatial resolution remote-sensing data, which are automatically captured and georeferenced, to assess damage following natural and man-made disasters, in addition to, or instead of employing the older methods of walking house-to-house for surveys, or photographing individual buildings from an airplane. This research establishes quantitative relationships between the damage states observed at ground-level, and those observed from space using high spatial resolution remote-sensing data, for windstorms, for individual site-built one- or two-family residences (FR12). "Degrees of Damage" (DOD) from the Enhanced Fujita (EF) Scale were determined for groundbased damage states; damage states were also assigned for remote-sensing imagery, using a modified version of Womble's Remote-Sensing (RS) Damage Scale. The preliminary developed model can be used to predict the ground-level damage state using remote-sensing imagery, which could significantly lessen the time and expense required to assess the damage following a windstorm.

Heymsfield A.J.,U.S. National Center for Atmospheric Research | Giammanco I.M.,Insurance Institute for Business and Home Safety | Wright R.,Robert L. Wright and Assoc. Inc.
Geophysical Research Letters | Year: 2014

The physical properties of 2295 hailstones that developed in Great Plains (US) storms were measured, including their maximum dimension, mass, and cross-sectional area. Using these data, size-dependent relationships for their terminal velocities and kinetic energies are developed. These relationships can be used in weather forecast modeling and hail damage prediction and assessment. When hailstones are assumed to be spherical, their terminal velocities and kinetic energies are in agreement with what has been reported in previous studies. When non-sphericity is considered, which is the case for natural hail, the terminal velocities and kinetic energies are, on average, lower than those of spheres of the same maximum diameter, but can be larger. © 2014. American Geophysical Union. All Rights Reserved.

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