• Title/Summary/Keyword: windborne debris

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Windborne debris and damage risk models: a review

  • Holmes, J.D.
    • Wind and Structures
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    • v.13 no.2
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    • pp.95-108
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    • 2010
  • This review paper discusses research from the last few years relating to windborne debris risk models and the essential elements of engineering damage prediction models. Generic types of windborne debris are discussed. The results of studies of debris trajectories that are relevant to damage models are described - in particular the horizontal component of debris velocity as a function of distance travelled. The merits of impact momentum versus impact kinetic energy as a relevant parameter for predicting damage are considered, and how published data from generic cannon Impact tests can be used in risk models. The quantitative variation of debris impact damage with wind speed is also discussed. Finally the main elements of previously-proposed debris damage models are described.

Windborne debris risk analysis - Part II. Application to structural vulnerability modeling

  • Lin, Ning;Vanmarcke, Erik;Yau, Siu-Chung
    • Wind and Structures
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    • v.13 no.2
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    • pp.207-220
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    • 2010
  • The 'chain reaction' effect of the interaction between wind pressure and windborne debris is likely to be a major cause of damage to residential buildings during severe wind events. The current paper (Part II) concerns the quantification of such pressure-debris interaction in an advanced vulnerability model that integrates the debris risk model developed in Part I and a component-based wind-pressure damage model. This vulnerability model may be applied to predict the cumulative wind damage during the passage of particular hurricanes, to estimate annual hurricane losses, or to conduct system reliability analysis for residential developments, with the effect of windborne debris fully considered.

Windborne debris risk analysis - Part I. Introduction and methodology

  • Lin, Ning;Vanmarcke, Erik
    • Wind and Structures
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    • v.13 no.2
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    • pp.191-206
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    • 2010
  • Windborne debris is a major cause of structural damage during severe windstorms and hurricanes owing to its direct impact on building envelopes as well as to the 'chain reaction' failure mechanism it induces by interacting with wind pressure damage. Estimation of debris risk is an important component in evaluating wind damage risk to residential developments. A debris risk model developed by the authors enables one to analytically aggregate damage threats to a building from different types of debris originating from neighboring buildings. This model is extended herein to a general debris risk analysis methodology that is then incorporated into a vulnerability model accounting for the temporal evolution of the interaction between pressure damage and debris damage during storm passage. The current paper (Part I) introduces the debris risk analysis methodology, establishing the mathematical modeling framework. Stochastic models are proposed to estimate the probability distributions of debris trajectory parameters used in the method. It is shown that model statistics can be estimated from available information from wind-tunnel experiments and post-damage surveys. The incorporation of the methodology into vulnerability modeling is described in Part II.

Roof tile frangibility and puncture of metal window shutters

  • Laboy-Rodriguez, Sylvia T.;Smith, Daniel;Gurley, Kurtis R.;Masters, Forrest J.
    • Wind and Structures
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    • v.17 no.2
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    • pp.185-202
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    • 2013
  • The goal of this study was to investigate the vulnerability of roof tile systems and metal shutters to roof tile debris. Three phases addressed the performance of tile roof systems and metal shutters impacted by roof tile debris. The first phase experimentally evaluated the tile fragment size and quantity generated by a tile striking a tile roof system. The second phase experimentally quantified the puncture vulnerability of common metal panel shutter systems as a function of tile fragment impact speed. The third phase provided context for interpretation of the experimental results through the use of a tile trajectory model. The results provide supporting evidence that while metal panel window shutters provide significant protection against a prevalent form of windborne debris, these systems are vulnerable to tile fragment puncture in design level tropical cyclones. These findings correlate with field observations made after Hurricane Charley (2004).

Pressure field of a rotating square plate with application to windborne debris

  • Martinez-Vazquez, P.;Kakimpa, B.;Sterling, M.;Baker, C.J.;Quinn, A.D.;Richards, P.J.;Owen, J.S.
    • Wind and Structures
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    • v.15 no.6
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    • pp.509-529
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    • 2012
  • Traditionally, a quasi steady response concerning the aerodynamic force and moment coefficients acting on a flat plate while 'flying' through the air has been assumed. Such an assumption has enabled the flight paths of windborne debris to be predicted and an indication of its potential damage to be inferred. In order to investigate this assumption in detail, a series of physical and numerical simulations relating to flat plates subject to autorotation has been undertaken. The physical experiments have been carried out using a novel pressure acquisition technique which provides a description of the pressure distribution on a square plate which was allowed to auto-rotate at different speeds by modifying the velocity of the incoming flow. The current work has for the first time, enabled characteristic pressure signals on the surface of an auto-rotating flat plate to be attributed to vortex shedding.

Autorotation of square plates, with application to windborne debris

  • Martinez-Vazquez, P.;Sterling, M.;Baker, C.J.;Quinn, A.D.;Richards, P.J.
    • Wind and Structures
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    • v.14 no.2
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    • pp.167-186
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    • 2011
  • This paper presents the results of measurements relating to the aerodynamic forces on flat square plates which were allowed to rotate at different speeds about their horizontal axis, by modifying the velocity of the incoming flow. A 1 m square test-sheet and a 0.3 m square test-sheet were fitted with a number of pressure sensors in order to obtain information relating to the instantaneous pressure distribution acting on the test-sheet; a compact gyroscope to record the angular velocity during the rotational motion was also implemented. Previous work on autorotation has illustrated that the angular velocity varies with respect to the torque induced by the wind, the thickness and aspect ratio of the test-sheet, any frictional effects present at the bearings, and the vorticity generated through the interaction between the plate and the wind flow. The current paper sets out a method based on the solution of the equation of motion of a rotating plate which enables the determination of angular velocities on autorotating elements to be predicted. This approach is then used in conjunction with the experimental data in order to evaluate the damping introduced by the frictional effects at the bearings during steady autorotation.

CFD modelling of free-flight and auto-rotation of plate type debris

  • Kakimpa, B.;Hargreaves, D.M.;Owen, J.S.;Martinez-Vazquez, P.;Baker, C.J.;Sterling, M.;Quinn, A.D.
    • Wind and Structures
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    • v.13 no.2
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    • pp.169-189
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    • 2010
  • This paper describes the use of coupled Computational Fluid Dynamics (CFD) and Rigid Body Dynamics (RBD) in modelling the aerodynamic behaviour of wind-borne plate type objects. Unsteady 2D and 3D Reynolds Averaged Navier-Stokes (RANS) CFD models are used to simulate the unsteady and non-uniform flow field surrounding static, forced rotating, auto-rotating and free-flying plates. The auto-rotation phenomenon itself is strongly influenced by vortex shedding, and the realisable k-epsilon turbulence modelling approach is used, with a second order implicit time advancement scheme and equal or higher order advection schemes for the flow variables. Sequentially coupling the CFD code with a RBD solver allows a more detailed modelling of the Fluid-Structure Interaction (FSI) behaviour of the plate and how this influences plate motion. The results are compared against wind tunnel experiments on auto-rotating plates and an existing 3D analytical model.