Windborne Debris Research Articles

Numerical investigation of turbulence effect on flight trajectory of spherical windborne debris: A multi-layered approach

Accurate modeling of the turbulent wind field is a crucial component of risk analysis for structures to windborne debris damage. Existing studies typically simplify the complexities of wind turbulence, and the potential influence on the accuracy of debris flight modeling has not been systematically demonstrated. This study takes a multi-layered approach to numerically simulate the flight trajectory of spherical debris in a turbulent wind field. Complexities are incrementally added to the simulated wind field to systematically investigate the influence of spatial correlation and non-Gaussian features of turbulence on debris flight behavior. The sensitivity of debris flight behavior to turbulent wind features will inform the design of debris flight tracking wind tunnel tests and building façade debris vulnerability modeling efforts.

Investigation of aerodynamic effects of rotation on 6-DOF motion of flat square plate based on free flight experiments

Plate-like debris is common windborne debris in windstorms. Although the 3-degree-of-freedom (3-DOF) motion (two translational DOFs and one rotational DOF) of flat plates has been widely investigated in previous studies, the 6-DOF motion is more likely to occur in real storms. We investigate the 6-DOF motion by performing free flight experiments of a square plate with different initial orientations under uniforms flow in a wind tunnel. Two cameras are used to record the flight motion of the plate. Then the recordings are processed in an image analysis software to estimate the kinematics of the plate. We first investigate the characteristics of the rotational motion. According to the rotational characteristics, the plate trajectories are categorized into four flight patterns: flutter, tumbling, transition, and quasi-translation. Then we explore the rotational effects on the aerodynamics. We propose a hypothesis that the magnitude and direction of the rotational forces depend on the angular velocity and the relative wind velocity. We also propose a hypothesis that the rotational moment has negligible influences on the direction of the instantaneous moment. These hypotheses are supported by the experimental results. These verified hypotheses may be helpful for modelling the aerodynamics of the 6-DOF motion of flat plates.

Structural Performance and Design of Aluminum Claddings Subjected to Windborne Debris Impact

Aluminum cladding panels have been used in some of the most iconic buildings around the world due to their durability, aesthetic appeal, and longevity. These panels play a critical role as the first line of defense against external forces such as wind and rain; therefore, the appropriateness of the design and resilience of aluminum cladding panels must be ensured. Previous researchers have conducted very minimal research on aluminum panels subjected to windborne debris impact. Their scope was limited to studying the response of panels when they are targeted at the center. The influence of various structural and load-related parameters on the response of such claddings has yet to be investigated. Furthermore, no design guidelines are readily available that engineers can use to predict the response of aluminum cladding panels when subjected to such loads considering various conditions (location of impact, projectile’s material, angle of impact, velocity of impact, unsupported length, and the geometry of the panels). The main aim of this paper was to develop some design guidelines that engineers can use to predict the response of aluminum cladding panels exposed to windborne debris impact. To achieve this, a series of parametric studies was conducted to generate a data bank. These parametric studies were performed with the help of a robust numerical model that has been validated with experimental results. The parametric sensitivity study revealed that the angle of impact was the most influential parameter, causing an 80% reduction in the peak impact force with a 50% decrease in the angle. The velocity, plate thickness, location of impact, and unsupported length also significantly influenced the panel’s response. The alloy type emerged as a dominant factor affecting the maximum and residual deflections. Regression equations were formulated based on the generated dataset to accurately predict the peak impact force, maximum central deflection, and residual deflection of solid aluminum cladding panels. The proposed prediction equations offer a better alternative to experimental testing.

Predicting Trajectories of Plate-Type Wind-Borne Debris in Turbulent Wind Flow with Uncertainties

Debris poses multifaceted risks and jeopardizes various aspects of the environment, human health, safety, and infrastructure. The debris trajectory in turbulent wind flow is more dispersed due to the inherent randomness of the turbulent winds. This paper investigates the three-dimensional trajectories of plate-type wind-borne debris in turbulent wind fields via the method of numerical simulation. A 3D probabilistic trajectory model of plate-type wind-borne debris is developed. The debris trajectories are numerically calculated by solving the governing equation of debris motion and by introducing turbulent wind flows based on the near-ground wind field measured in the wind tunnel to account for the probability characteristics of the debris trajectory. The dimensionless velocities and displacements of the debris trajectory show good agreement with the experimental data in wind tunnel tests, confirming the rationality of the probabilistic trajectory model. Based on the validated trajectory model, the probability characteristics of the debris impact position, impact velocity, and kinetic energy, debris angular displacement, and angular velocity are analyzed in detail under five different wind attack angles. The proposed probabilistic model of plate-type debris in turbulent wind flow provides an accurate and effective method for predicting debris trajectory in three-dimensional space.

Finite element analysis of laminated composite stiffened hyperbolic paraboloid hypershell subjected to impact loading

Laminated composite has produced a solution in the weight sensitive branches of engineering due to its low specific weight, high specific strength and weathering resistance. It is its low transverse shear capacity under impact load has become a great concern for the researchers for its successful implementation in different industrial sectors. Impact which is likely to occur in cyclone prone zones and aircraft bases where wind borne debris causes the same. The sudden strike may cause delamination, crack in the epoxy medium or tearing of fibers which remains suppressed under the lamina and eventually causes collapse. This study is an effort to analyze the laminated composite hyparshell under impact load with simply-supported boundary conditions. Installation of stiffeners in various positions become unavoidable in certain cases and which is optimized and the best possible combination is concluded. A detailed comparative study of deformation, stress and strain is done with respect to various impactor velocities. The analysis is done by finite element software Ansys 2022 R1.

Impact Resistance Test of Cladding by Using Gravel

Multiple reports have emphasized the significance of protecting cladding from windborne debris or falling cinders during strong winds or volcanic eruptions. Japan has no available building codes or standards for protecting the cladding against the windborne debris or falling cinders. In contrast, certain specifications for cladding performance when impacted by windborne debris, along with associated testing methods, are outlined in American, ISO, and JIS standards. A series of impact tests was conducted on selected specimens, like cladding used for residential projects, to evaluate their impact resistance performance. This study presents the outcomes of the impact performance tests, including their destruction modes, for representative materials of cladding like float glass, Japanese tiled roof, batten-seam roof, and slate-tiled roof. The tests were conducted using an air cannon as the gravel-propulsion device. The impact-resistant speed corresponding to the mass of gravel was clarified for the specimens.

Performance of reinforced lightweight geopolymer composite panels subjected to windborne debris impacts

Lightweight panels have been widely employed as building envelopes in construction. As a result of the rising demand for environmentally friendly building materials, the authors recently developed a lightweight geopolymer composite (LGC) material and investigated the performance of reinforced LGC panels under static loading. Superior performance of LGC panels as compared to conventional panels such as autoclaved aerated concrete (AAC) panels has been observed, demonstrating their potential applications. During strong winds, building envelopes might be subjected to windborne debris impact, which could threaten residents and facilities and lead to structural failure. To explore the application potentials of LGC panels in strong wind regions, in this study, the performances of LGC panels subjected to windborne debris impact were investigated and compared with those of AAC panels by using a pneumatic cannon testing system. The failure modes and damage levels under different impact scenarios of LGC and AAC panels and their impact resistance capacities were obtained, compared and quantified in terms of the projectile residual velocity, penetration length and opening size. The effects of matrix materials, panel thicknesses, impact locations, reinforcement spacings and projectile impact velocities on their impact resistance performance were analyzed. For comparison, the punching shear capacities of the panels were also quasi-statically tested and analyzed subjected to the same projectile employed in the impact tests.

Three-Dimensional Flight Trajectories and Impact Damage Prediction Model for Wind-Borne Debris

The risk of damage of glass curtain walls in residential areas caused by impact of wind-borne debris has been given increasing importance. In this paper, by incorporating the numerical analysis of three-dimensional (3D) flight trajectories of wind-borne debris and computational fluid dynamics (CFD) simulation of the local wind environment in the context of buildings group, a novel impact damage prediction model for the glass curtain wall of urban buildings is proposed. To this end, the 3D flight trajectories and characteristics of plate-type debris are first studied by solving the 3D equation of motion of debris, of which the aerodynamic coefficients of plate-type debris is obtained by CFD numerical simulation. The flight characteristics of debris with different initial parameters are analyzed, showing that the properties of debris and initial conditions have significant effect on the flight trajectories and impact position of plate-type debris. Further, an impact damage prediction model for the glass curtain wall of an urban building is proposed. In the proposed model, the flight trajectory analysis of the wind-borne debris is embedded in the context of the local wind environment in a residential area obtained by CFD simulation. The damage caused by the impact of debris on the glass curtain wall of the buildings is then analyzed and illustrated by an example. The proposed model is of great significance for the wind damage analysis of urban building glass curtain walls considering local wind environment and real trajectories of debris.

Fragility Modeling of Urban Building Envelopes Subjected to Windborne Debris Hazards

Fragility Modeling of Urban Building Envelopes Subjected to Windborne Debris Hazards

Typhoon Damage Analysis of Typical Vulnerable Structures

Typhoon, as one of the most devastating natural hazards, has brought billions of property losses and threaten the safety of people around the world, and meanwhile, damage and collapse of various urban structures are the main components of direct losses caused by typhoon. Therefore, the review focus on the introduction on the impact and poster researches about three kinds of typhoon action, external wind pressure, internal wind pressure and wind-borne debris, on the structures at first, and then summarize the failure modes for three kinds of vulnerable structures, including bungalows, light steel industrial buildings and advertisement boards, respectively. Based on the data and field investigations on several severe or super typhoon, the failure modes of those structure start with the places where the elements are lack of potent connection and integrality, such as enclosure members, or the place where the stress concentration appears. This paper is looking forward to giving a assisting the engineers and scientists to improve the typhoon resistance measure or regulate the design of structures to prevent or alleviate the property loss and life security in typhoon in the field of structural analysis. This paper gives the summary on failure mechanism of vulnerable structures, and recommend the reinforcement trend on this field of structures.

Fragility analysis of curtain walls based on wind-borne debris considering wind environment

Increasing attention has been attached to the risk assessment and fragility analysis of envelopes of high-rise buildings subjected to the impact of wind-borne debris in hurricanes or typhoons. A probabilistic model of wind-borne debris is proposed in the present paper for risk assessment and fragility analysis of high-building curtain walls based on the numerical solution of three-dimensional flight trajectories of debris and the computational fluid dynamics simulation of local wind environment in a residential area. The influence of sources of randomness in the generation of debris, such as generated location, size, and initial attack angle, as well as local wind environment, on the location of debris impacting on the building curtain wall and the impact damage effect, are considered in the proposed model. The evolution of the probability characteristics of debris is driven by its physical flying behavior in the local wind environment, and the failure probability of each piece of glass of building curtain walls impacted by debris can be determined. Furthermore, a numerical algorithm is given for the fragility analysis under different incoming wind speeds, which can be used to determine the vulnerability and the fragility curve. Finally, two numerical examples for application to residential areas are provided. Results show that the proposed model can provide evaluation and prediction for wind disaster risk and fragility of high-rise buildings in urban areas.

Analyzing Safety Risk Imposed by Jobsite Debris to Nearby Built Environments Using Geometric Digital Twins and Vision-Based Deep Learning

Extreme wind events can pick up loose and small objects on the ground, and once the objects become airborne, they negatively impact surrounding communities due to the collision impact. In this regard, jobsites and laydown yards that involve construction materials such as gravel piles and crushed rocks could be the main sources of potential windborne debris during extreme wind events. To analyze safety risk and predict the damage imposed by jobsite debris to nearby built environments, a new computer vision-based risk assessment based on geometric digital twins of jobsite debris is proposed for the reliability analysis on glazing systems of dwellings located on nearby jobsites. The impact of a gravel pile in a railroad jobsite on nearby buildings and residential environments was studied based on extreme wind event scenarios, and the failure risk of the building glazing system was computed. The risk associated with jobsite debris during extreme wind events and their impact on neighboring communities are analyzed through three computing modules: (1) satellite imagery-based terrain modeling to study 3D characteristics of the at-risk built environment; (2) analyzing visual data from Google Street View to assess the risk associated with glazing panels of dwellings in the communities; and (3) analyzing visual data from a jobsite to quantify the impact of jobsite debris, to associate its safety risk to neighboring communities. The proposed method can provide an immediate heads up for those who reside nearby jobsites, allowing to take required preemptive actions to protect their habitation against potential windborne debris. Practitioners will also be informed of such jobsite debris-related risk before extreme wind events to better secure their jobsites for the risk mitigation.

Data-driven framework for automated simulation of wind and windborne debris effects for hurricane regional loss estimation

Hurricanes are a major driver of disaster losses in the United States; these losses can be minimized through the development of open-source scientific workflows that conduct site-specific, building-specific and component-level loss assessments across entire regions. While today's open-source workflows provide parcel-level granularity, common use of non-specific building characterizations limits the fidelity of these representations, particularly with respect to site-specific effects of wind and windborne debris (WBD) hazards. In response, this paper presents a new framework that utilizes publicly available data to enable modeling and analysis capabilities necessary to (1) capture site-specific, building-specific exposure to wind and WBD hazards and (2) propagate these demands through the building envelope's load path. The proposed data-driven framework is applied to an office building located in Florida's Bay County, the landfall site of Hurricane Michael. Leveraging a new building data model for regional loss estimation, this case study demonstrates the framework's use of open data to automate population of site models, WBD missile environment, wind pressure distributions, and component capacities to enable fault tree analyses for target and source buildings. The proposed approach can be utilized to identify hazard- and building-specific, component-level damage consistent with actual damage observed in Hurricane Michael.

Flight characteristics of rod-shaped windborne debris objects in atmospheric boundary layer winds

The presented study explored the flight characteristics of rod-shaped debris objects in neutrally-stratified atmospheric boundary layer (ABL) winds. Despite the fact that rod-shaped debris objects, such as lumbers, are a common type of debris observed during extreme wind events, their three-dimensional motions had not been fully characterized and the understanding of their flight trajectories was limited to the outcome of only a few wind tunnel tests. To address the outlined research gaps, this study established a coupled simulation framework, which utilized both computational fluid dynamics (CFD) and rigid body dynamics (RBD). After validating this framework using the experimental test data, the flight trajectories of a set of rod-shaped debris objects were first evaluated in uniform winds. With placing the rod's longitudinal axis in both along-wind and cross-wind directions, the debris flight motions were characterized for various initial pitch angles. After appropriate verifications, the simulations were extended to investigate the flight of rod-shaped objects in ABL winds. The main debris flight properties, including displacement and velocity profiles, were systematically extracted over time, taking into consideration various influential factors. With the wealth of debris flight data generated through the conducted CFD-RBD simulations, predictive models were developed for assessing the kinetic energy associated with the flight of rod-shaped debris objects.

A Framework to Model the Wind-Induced Losses in Buildings during Hurricanes

Wind-induced loss modeling plays a key role in insurance risk management. Hence, a flexible vulnerability framework is to be developed for residential and commercial buildings. This model predicts the losses induced by hurricane wind pressure, wind-borne debris and wind-driven rain. Twenty-five different key variables of the buildings and environment are used as attributes for the simulations. Model results are validated using the Florida Public Hurricane Loss Models (FPHLM) and HAZUS wind vulnerability functions. New contributions include (1) a Markovian roof-aging model to address decreases in roof performance due to aging, and (2) occupancy-specific interior value models based on FEMA Normative quantities for the systematic evaluation of interior value applicable to archetype buildings. A simple wind debris impact model and wind-driven rain intrusion model is also introduced. The influence of the number of stories, roof aging, and window vulnerability resulting in damage are investigated in this article to ensure consistency of the results. The proposed framework enables insurance loss modelers to make judicious choices of input variables based on partial or detailed knowledge about the building to model losses. Future research should focus on validation and calibration using good-quality insurance claims data.

Exogenous windborne debris: Definition and required extent of surrounding buildings for modeling in hurricanes

Modeling and estimating the damage to the built environment caused by hurricane winds is an essential requirement to enhance community resilience. Consideration of damage to a building’s envelope caused by windborne debris impact is necessary. To model this damage for a certain subdivision of houses, debris generated in neighboring subdivisions, defined as exogenous debris, must be taken into account. Existing physics-based damage estimation models do not consider the effect exogenous windborne debris has on the estimated damage due to hurricane winds. This paper provides a methodology to identify the extent of the neighboring subdivisions that needs to be considered during damage simulation to accurately account for exogenous windborne debris. The presented methodology is based on first identifying the extent of the neighboring subdivisions through a simulation-based strategy which follows an iterative scheme. For each size increment, the iterative scheme estimates the number of exogenous windborne debris using a physics-based damage estimation model. The single building solution is then generalized to a subdivision of any arbitrary shape. The proposed methodology is applied to analyze a hypothetical residential community in Miami, FL. Analysis results show the effect on the required extent of the neighboring subdivisions of the hurricane maximum wind speed, the floor-area ratio and the resistance of the building envelope components. The analysis concludes with a regression model that can be used to estimate the size of the neighboring subdivisions to be used in damage estimation models.

A framework for estimating water ingress due to hurricane rainfall

Hurricanes can have adverse effects on residential communities and pose a significant risk to their economic prosperity. The ingress of water into a building due to wind-driven rain (WDR) and inland flooding can cause significant damage leading to downtime or temporary loss of housing. Existing frameworks focus on estimating the amount of water ingress due to WDR and inland flooding separately. This paper provides a comprehensive framework that considers both WDR and inland flooding when estimating the amount of water ingress into residential buildings due to hurricane rainfall. The framework estimates the water ingress due to WDR by combining the WDR intensity with the perforated area of the building envelopes. The intensity of the WDR is quantified using an Eulerian Multi-phase Model. The buildings’ envelope is considered susceptible to damage from the impact of windborne debris and excessive dynamic wind pressure. The framework to characterize and quantify inland flooding uses a coupled hydrologic-hydrodynamic model to estimate the inundation depth at each building. A case study consisting of a residential community in Houston, TX, which is subject to Hurricane Harvey illustrates the ability of the framework to capture the influence of WDR and inland flooding when quantifying water ingress.

Dynamic failure behavior of steel wire mesh subjected to medium velocity impact: Experiments and simulations

Considerable property damage is caused by windborne debris during extreme weather. The object of interest in this study, steel wire mesh, is an effective means of providing protection against windborne debris. However, the design and manufacture of security screens made of wire mesh typically depend on a laborious and imprecise trial-and-error process. Additionally, this anisotropic, inhomogeneous, and porous material comprising in-contact wires has rarely been examined in a comprehensive manner. Considering these issues, the current research experimentally tested the impact response of plain-weave steel wire mesh by firing a spherical projectile in a velocity regime ranging from 112 m/s to 152 m/s. The deformation and failure mechanisms of the wire mesh during the impact process were investigated via high-speed photography. The results showed that the wire mesh behaved as a membrane and failed mainly in tension over the impact velocity range of interest. Further, with a detailed finite element model consisting of interlaced warp and weft wires, additional virtual tests were carried out at a broader velocity range of 20–200 m/s. The findings indicated a linear relationship between residual velocity and impact velocity under a velocity range that exceeded the ballistic limit. The energy absorbed by the wire mesh increased with impact velocity (or impact energy) before the material reached peak absorption at the ballistic limit. Beyond this threshold, the energy absorption gradually declined to an asymptotic level. Such energy absorption was well correlated with the extent of transverse deformation in the wire mesh. Internal energy due to the deformation of wires and frictional energy associated with the interactions between sliding wires at their crossovers were two primary energy absorbing mechanisms. Moreover, the effects of impact location, clamped wire direction and projectile size were analyzed.

AI-based risk assessment for construction site disaster preparedness through deep learning-based digital twinning

Hurricanes are among the most devastating natural disasters in the United States, causing billions of dollars of property damage and insured losses. During extreme wind events, unsecured objects in jobsites can easily become airborne debris, which results in substantial loss to construction projects and neighboring communities. Towards a systematic disaster preparedness in construction jobsites, this paper presents a novel vision-based digital twinning and threat assessment framework. We encode the context of disaster risk into deep-learning architectures to identify and analyze the characteristics and impacts of potential wind-borne debris in construction site digital twin models. Case studies on nine piles of construction materials are presented to demonstrate and discuss the fidelity of the proposed computational modules. The proposed methods are expected to help provide heads up for practitioners to quickly recognize, localize, and assess potential wind-borne derbies in construction jobsites, and thereby implementing hurricane preparedness in an effective and timely manner.

Risk and fragility assessment of residential wooden buildings subject to hurricane winds

Hurricanes are one of the major causes of damage and loss to residential wooden buildings in the United States. The study of hurricane-imposed risks to residential wooden buildings is, therefore, a fundamental step to mitigate these damages and losses. Within this context, a probabilistic methodology is provided for the fragility analysis of residential wooden buildings. Two damage mechanisms are considered in this methodology, excessive dynamic wind pressure and impact from windborne debris. Unlike existing frameworks, the methodology defines the geometric configuration as well as the required extension of the neighboring buildings to estimate the damage from both mechanisms. A case study illustrates the methodology on residential communities composed of archetype gable-roof buildings. Ten construction cases are defined to cover a range of resistances of building components for both considered damage mechanisms. Three floor-area ratios (FAR) are also considered. The resulting fragility curves highlight: (1) the effect of the FAR on enhancing the performance of residential buildings due to the effect of shielding; and (2) the significance of windborne debris in increasing the estimated hurricane risk. The estimated fragility curves can be used to directly model residential buildings in community resilience frameworks.