Failures of roof asphalt shingles under high winds have been reported to occur at wind speeds lower than the shingle performance classification. The understanding of the progressive failure mechanisms of shingles subjected to high-wind pressures has been hindered by difficulty in accurately quantifying uplifts and wind-induced pressures with high spatial resolution, especially for large-scale wind test setups that simulate realistic scenarios. This paper reports on an experimental study to assess the use of three-dimensional digital image correlation ('StereoDIC') to accurately measure full-field surface deformations of shingles installed on full-scale roof structures and subjected to realistic high winds. Deformation measurements were acquired on shingles installed on typical wood-frame roof panels and subjected to winds with speed up to 257 km/h (160 mph) using an outdoor wind tunnel. The specimens were designed to study the proposed test setup and StereoDIC measurement method for two different combinations of shingle surface coloration (and thus speckle pattern) and field of view. The experiments produced accurate local and full-field shingle deformation measurements. Different datasets were used to gain new insight into the influence of salient aspects of the wind test setup and deformation measurement method on the understanding of the temporal evolution of shingle uplift and failure mechanisms.

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.

Understanding of deformations and the progressive failure mechanisms of asphalt shingles under wind loads is key to develop wind-resistant roofing systems, as well as standard test methods to characterize strength under representative wind loads. In fact, failure of shingles rated as resistant to winds up to 150 mph have been reported at speeds below 115 mph. Damage associated with failure of roof shingles continues to be a major source of insurance claims. Though pressure measurements can be taken at discrete points using pressure taps, no technology has been successfully deployed to measure full-field deformations on roof shingles subjected to wind loads. This paper reports on a feasibility study of three-dimensional digital image correlation (3D-DIC) as a non-contacting technique to measure full-field displacements of roof shingles under high wind loads. Feasibility is assessed based on evidence from load testing of three-tab shingles mounted on a full-scale roof panel specimen that was subjected to straight winds with speed up to 155 mph. Uplift displacements were measured on a target shingle tab. The natural color variations on the shingle exposed surface were used to provide a suitable speckle pattern for 3D-DIC measurements. It is shown that consistent 3D-DIC uplift displacement maps can be obtained up to failure. The evidence gained also highlights the importance of understanding the influence of time-dependent shingle material deformations, together with the progressive physical damage along the sealant strip.

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. (C) 2014 Elsevier Ltd. All rights reserved.

Post-hurricane damage assessments have documented the failure of wall components and connections including the loss of various types of siding materials. In addition, recent U.S. model building/energy code changes are expected to lead to increased use of continuous insulation, particularly foam sheathing attached to the exterior surface of light-frame wall framing, to achieve advanced energy code compliance. A particular need for multi-layer wall systems is the understanding of wind loads on the various layers so that designers and product manufacturers can ensure acceptable building envelope performance of energy efficient wall systems in high-wind events, such as hurricanes. To address the knowledge gaps and practical concerns related to multi-layer wall systems with air-permeable exterior cladding, the Foam Sheathing Committee (FSC) of the American Chemistry Council (ACC), the Vinyl Siding Institute (VSI), the National Association Home Builders Research Center (NAHB RC), State Farm Mutual Automobile Insurance Company, Insurance Institute for Business & Home Safety (IBHS), and others have initiated research into wind loads on layers of multilayer wall systems. Results presented in this paper include determination of wind

Mitigation of the damage caused by windstorms to low-rise buildings is a high priority in the wind engineering community. The development of cost-effective methods to withstand the effects of extreme winds can be advanced through improved modeling of wind loads acting on low-rise roof structures. This study explores the effects of the spatial and probabilistic characteristics of pressure fields on the aggregate uplift acting on roof panels of low-rise gable roof buildings representative of typical homes. Pressure time histories obtained at roof locations for buildings of varying roof slope at several angles of incidence in the boundary layer wind tunnel at Clemson University are used to characterize the correlation statistics between tap locations and model the marginal probability density function at individual tap locations. This information is incorporated into a multi-variate non-Gaussian simulation algorithm to study the effects of various levels of correlation on the aggregate uplift on sheathing panels. Comparisons are made between the simulated aggregate uplift and ASCE 7–98 provisions [Minimum Design Loads for Buildings and Other Structures, ASCE 7-98 Standard, American Society of Civil Engineers, New York [1]] as well as laboratory generated failure capacities for sheathing panels.

The paper reports progress in the development of a practical probabilistic model for the estimation of expected annual damage induced by hurricane winds in residential structures. The estimation of the damage is accomplished in several steps. First, basic damage modes for components of specific building types are defined. Second, the damage modes are combined in possible damage states, whose probabilities of occurrence are calculated as functions of wind speeds from Monte Carlo simulations conducted on engineering numerical models of typical houses. The paper describes the conceptual framework for the proposed model, and illustrates its application for a specific building type with hypothetical probabilistic input. Actual probabilistic input must be based on laboratory studies, postdamage surveys, insurance claims data, engineering analyses and judgment, and Monte Carlo simulation methods. The proposed component-based model is flexible and transparent. It is therefore capable of being readily scrutinized. The model can be used in conjunction with historical loss data, to which it can readily be calibrated.