• Wind and Structures
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• v.35 no.3
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• pp.213-227
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• 2022

The design of a building is a complex process that encompasses different fields: one of the most relevant is nowadays the energetic one, which has led to the introduction of new typologies of building envelopes. Among them, the Permeable Double Skin Façades (PDSF) are capable to reduce the solar impact and so to improve the energetic performances of the building. However, the aerodynamic characterization of a building with a PDSF is still little investigated in the current literature. The present paper proposes an experimental study to highlight the modifications induced by the outer porous façade in the aerodynamics of a building. A dedicated wind tunnel study is conducted on a rigid model of a prismatic high-rise building, where different façade configurations are tested. Specifically, the single-layer façade is compared to two PDSFs, the former realized with perforated metal and the latter with expanded metal. Outcomes of the tests allow estimating the cladding loads for all the configurations, quantifying the shielding effects ascribable to the porous layers that are translated in a significant reduction of the design pressure that could be up to 50%. Moreover, the impact of the PDSFs on the vortex shedding is investigated, suggesting the capability of the façade to suppress the generation of synchronised vortices and so mitigate the structural response of the building.

• Wind and Structures
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• v.28 no.6
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• pp.389-404
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• 2019

In coastal regions, it is common to witness significant damages on low-rise buildings caused by hurricanes and other extreme wind events. These damages start at high pressure zones or weak building components, and then cascade to other building parts. The state-of-the-art in experimental and numerical aerodynamic load evaluation is to assume buildings with intact envelopes where wind acts only on the external walls and correct for internal pressure through separate aerodynamic studies. This approach fails to explain the effect of openings on (i) the external pressure, (ii) internal partition walls; and (iii) the load sharing between internal and external walls. During extreme events, non-structural components (e.g., windows, doors or rooftiles) could fail allowing the wind flow to enter the building, which can subject the internal walls to lateral loads that potentially can exceed their load capacities. Internal walls are typically designed for lower capacities compared to external walls. In the present work, an anticipated damage development scenario is modelled for a four-story building with a stepped gable roof. LES is used to examine the change in the internal and external wind flows for different level of assumed damages (starting from an intact building up to a case with failure in most windows and doors are observed). This study demonstrates that damages in non-structural components can increase the wind risk on the structural elements due to changes in the loading patterns. It also highlights the load sharing mechanisms in low rise buildings.

• Wind and Structures
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• v.37 no.4
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• pp.255-274
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• 2023

The aim of this paper is to enhance the accuracy of predicting time-averaged external surface pressures on low-rise buildings by utilizing Computational Fluid Dynamics (CFD) simulations. To achieve this, benchmark studies of the Silsoe cube and the Texas Tech University (TTU) experimental building are employed for comparison with simulation results. The paper is structured into three main sections. In the initial part, an appropriate domain size is selected based on the precision of mean pressure coefficients on the windward face of the cube, utilizing Reynolds Averaged Navier-Stokes (RANS) turbulence models. Subsequently, recommendations regarding the optimal computational domain size for an isolated building are provided based on revised findings. Moving on to the second part, the Silsoe cube model is examined within a horizontally homogeneous computational domain using more accurate turbulence models, such as Large Eddy Simulation (LES) and hybrid RANS-LES models. For computational efficiency, transient simulation settings are employed, building upon previous studies by the authors at the Windstorm Impact, Science, and Engineering (WISE) Lab, Louisiana State University (LSU). An optimal meshing strategy is determined for LES based on a grid convergence study. Three hybrid RANS-LES cases are investigated to achieve desired enhancements in the distribution of mean pressure coefficients on the Silsoe cube. In the final part, a 1:10 scale model of the TTU building is studied, incorporating the insights gained from the second part. The generated flow characteristics, including vertical profiles of mean velocity, turbulence intensity, and velocity spectra (small and large eddies), exhibit good agreement with full-scale (TTU) measurements. The results indicate promising roof pressures achieved through the careful consideration of meshing strategy, time step, domain size, inflow turbulence, near-wall treatment, and turbulence models. Moreover, this paper demonstrates an improvement in mean roof pressures compared to other state-of-the-art studies, thus highlighting the significance of CFD simulations in building aerodynamics.

• Wind and Structures
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• v.30 no.2
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• pp.155-163
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• 2020

Previous research has shown that wind acceleration components produce a signal that can vibrate single-degree of-freedom oscillators, whose dynamic responses enable to configure design spectra for structures subject to wind. These wind design spectra present an alternative method for evaluating the dynamic response of structures and are a suitable tool for running modal analyses. Here, a generalised method for producing wind design spectra is proposed. The method consists of scaling existing spectra to adjust to a wider range of building properties and terrain conditions. The modelling technique is tested on a benchmark building to prove that its results are consistent with experimental evidence reported in the past.

• Wind and Structures
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• v.31 no.4
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• pp.335-350
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• 2020

In coastal residential communities, especially along the coastline, flooding is a frequent natural hazard that impacts the area. To reduce the adverse effects of flooding, it is recommended to elevate coastal buildings to a certain safe level. However, post storm damage assessment has revealed severe damages sustained by elevated buildings' components such as roofs, walls, and floors. By elevating a structure and creating air gap underneath the floor, the wind velocity increases and the aerodynamics change. This results in varying wind loading and pressure distribution that are different from their slab on grade counterparts. To fill the current knowledge gap, a large-scale aerodynamic wind testing was conducted at the Wall of Wind experimental facility to evaluate the wind pressure distribution over the surfaces of a low-rise gable roof single-story elevated house. The study considered three different stilt heights. This paper presents the observed changes in local and area averaged peak pressure coefficients for the building surfaces of the studied cases. The aerodynamics of the elevated structures are explained. Comparisons are done with ASCE 7-16 and AS/NZS 1170.2 wind loading standards. For the floor surface, the study suggests a wind pressure zoning and pressure coefficients for each stilt height.

• Wind and Structures
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• v.5 no.2_3_4
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• pp.193-208
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• 2002

Previous studies have shown that Computational Wind Engineering (CWE) is still in its infancy and has a long way to go to become truly useful to the design practitioner. The present work focuses on more recent studies to identify progress on outstanding issues and improvements in the numerical simulation of wind effects on buildings. The paper reviews wind loading and environmental effects; it finds that, in spite of some interesting and visually impressive results produced with CWE, the numerical wind tunnel is still virtual rather than real and many more parallel studies - numerical and experimental - will be required to increase the level of confidence in the computational results.

• Wind and Structures
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• v.11 no.6
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• pp.427-440
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• 2008

Estimates of wind-induced wind effects on tall buildings are based largely on 1980s technology. Such estimates can vary significantly depending upon the wind engineering laboratory producing them. We describe an efficient database-assisted design (DAD) procedure allowing the realistic estimation of wind-induced internal forces with any mean recurrence interval in any individual member. The procedure makes use of (a) time series of directional aerodynamic pressures recorded simultaneously at typically hundreds of ports on the building surface, (b) directional wind climatological data, (c) micrometeorological modeling of ratios between wind speeds in open exposure and mean wind speeds at the top of the building, (d) a physically and probabilistically realistic aerodynamic/climatological interfacing model, and (e) modern computational resources for calculating internal forces and demand-to-capacity ratios for each member being designed. The procedure is applicable to tall buildings not susceptible to aeroelastic effects, and with sufficiently large dimensions to allow placement of the requisite pressure measurement tubes. The paper then addresses the issue of accounting explicitly for uncertainties in the factors that determine wind effects. Unlike for routine structures, for which simplifications inherent in standard provisions are acceptable, for tall buildings these uncertainties need to be considered with care, since over-simplified reliability estimates could defeat the purpose of ad-hoc wind tunnel tests.

• Wind and Structures
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• v.37 no.2
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• pp.163-178
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• 2023

The paper reviews and discusses the substantive changes to the ASCE 49-21 Standard, Wind Tunnel Testing for Buildings and Other Structures. The most significant changes are the requirements for wind field simulations that utilize (i) partial turbulence simulations, (ii) partial model simulations for the flow around building Appurtenances, along with requirements for determining wind loads on products that are used at multiple sites in various configurations. These modifications tend to have the effect of easing the precise scaling requirements for flow simulations because it is not generally possible to construct accurate models for small elements placed, for example, on large buildings at the scales typically available in boundary layer wind tunnels. Additional discussion is provided on changes to the Standard with respect to measurement accuracy and data acquisition parameters, such as duration of tests, which are also related to scaling requirements. Finally, research needs with respect to aerodynamic mechanisms are proposed, with the goal of improving the understanding of the role of turbulence on separated-reattaching flows on building surfaces in order to continue to improve the wind tunnel method for determining design wind loads.

• Wind and Structures
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• v.2 no.4
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• pp.253-266
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• 1999

This paper presents the effects of free-stream turbulence on streamwise surface pressure fluctuations on two-dimensional rectangular cylinders. Particular attention is given to possible effects of turbulence integral scale on fluctuation and peak pressures. The mean, standard deviation, peak pressure coefficients, spectra and cross-correlation of fluctuating pressures were measured to investigate the nature of the separation and reattachment phenomenon in turbulent flows over a wide range of turbulence intensity and integral scale.

• Journal of the Korean Professional Engineers Association
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• v.33 no.6
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• pp.38-44
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• 2000

This article describes the air conditioning and control system of cabin which commertial aircrafts have adapted extensively upto now. Even though the aircrafts requires the study of the aerodynamics to produce the life in the air, most of internal system should utilize mechanical, electrical, and electronic system used on conventional appliances of industries. Therefore, all of industries are invited to pay more interest in this field aggressively and suggested to think the aircraft as a building simply moving in the sky.