• Wind and Structures
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• v.10 no.4
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• pp.383-398
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• 2007

The paper describes a study of the effects of structural coupling on the wind-induced response of twin tall buildings connected by a skybridge. Development of a dual high-frequency force balance used in wind tunnel investigation and background information on the methodology employed in analysis are presented. Comparisons of the wind-induced building response (rooftop acceleration) of structurally coupled and uncoupled twin buildings are provided and the influence of structural coupling is assessed. It is found that the adverse aerodynamic interference effects caused by close proximity of the buildings can be significantly reduced by the coupling. Neglecting of such interactions may lead to excessively conservative estimates of the wind-induced response of the buildings. The presented findings suggest that structural coupling should be included in wind-resistant design of twin tall buildings.

• International Journal of High-Rise Buildings
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• v.11 no.4
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• pp.287-300
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• 2022

Unconventional structures are getting more popular in recent days. Large-span roofs are used for many structures, such as airports, stadiums, and conventional halls. Identifying the pressure distribution and wind load acting on those structures is essential. This paper offers a collaborative study of computational fluid dynamics (CFD) simulations and wind tunnel tests for assessing wind pressure distribution for a building with a combined slender curved roof. The hybrid turbulence model, Improved Delayed Detached Eddy Simulation (IDDES), simulates the open terrain turbulent flow field. The wind-induced local pressure coefficients on complex roof structures and the turbulent flow field around the structure were thus calculated based upon open terrain wind flow simulated with the FLUENT software. Local pressure measurements were investigated in a boundary layer wind tunnel simultaneous to the simulation to determine the pressure coefficient distributions. The results predicted by CFD were found to be consistent with the wind tunnel test results. The comparative study validated that the recommended IDDES model and the vortex method associated with CFD simulation are suitable tools for structural engineers to evaluate wind effects on long-span complex roofs and plan irregular buildings during the design stage.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.6
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• pp.127-133
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• 2013

The purpose of this study was to investigate maximum and minimum grain size which eroded by wind according to soil and wind conditions, such as top soil water content, roughness, land slope, wind velocity and proportion of grain size under 0.84mm. For performing this study, portable wind erosion tunnel was designed and utilized during field test, which facilitated measuring actual wind erosions under artificially controlled wind conditions. In the result, maximum, minimum grain size had strong negative correlation with roughness while weak positive correlation with wind velocity. Also, Slope which means the effect of gravity also influence grain size erodible by winds. Based on these results, regression equations were suggested for predicting maximum and minimum grain sizes by using multiple linear regression analysis from SPSS 20.0. The equation for maximum grain size erodible by winds showed a good agreement with the observed data with $R^2$=0.896. Other equation for minimum grain size had $R^2$=0.777.

• Wind and Structures
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• v.23 no.5
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• pp.405-420
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• 2016

Section model wind tunnel test is currently the main technique to investigate the flutter performance of long-span bridges. Further study about applying the wind tunnel test results to the aerodynamic optimization is still needed. Systematical parameters and test principle of the bridge section model are determined by using three long-span steel truss suspension bridges. The flutter critical wind at different attack angles is obtained through section model flutter test. Under the most unfavorable working condition, tests to investigate the effects that upper central stabilized plate, lower central stabilized plate and horizontal stabilized plate have on the flutter performance of the main beam were conducted. According to the test results, the optimal aerodynamic measure was chosen to meet the requirements of the bridge wind resistance in consideration of safety, economy and aesthetics. At last the credibility of the results is confirmed by full bridge aerodynamic elastic model test. That the flutter reduced wind speed of long-span steel truss suspension bridges stays approximately between 4 to 5 is concluded as a reference for the investigation of the flutter performance of future similar steel truss girder suspension bridges.

• Wind and Structures
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• v.20 no.1
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• pp.15-36
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• 2015

Characterization of wind flows over a complex terrain, especially mountain-gorge terrain (referred to as the very complex terrain with rolling mountains and deep narrow gorges), is an important issue for design and operation of long-span bridges constructed in this area. In both wind tunnel testing and numerical simulation, a transition section is often used to connect the wind tunnel floor or computational domain bottom and the boundary top of the terrain model in order to generate a smooth flow transition over the edge of the terrain model. Although the transition section plays an important role in simulation of wind field over complex terrain, an appropriate shape needs investigation. In this study, two principles for selecting an appropriate shape of boundary transition section were proposed, and a theoretical curve serving for the mountain-gorge terrain model was derived based on potential flow theory around a circular cylinder. Then a two-dimensional (2-D) simulation was used to compare the flow transition performance between the proposed curved transition section and the traditional ramp transition section in a wind tunnel. Furthermore, the wind velocity field induced by the curved transition section with an equivalent slope of $30^{\circ}$ was investigated in detail, and a parameter called the 'velocity stability factor' was defined; an analytical model for predicting the velocity stability factor was also proposed. The results show that the proposed curved transition section has a better flow transition performance compared with the traditional ramp transition section. The proposed analytical model can also adequately predict the velocity stability factor of the wind field.

• Wind and Structures
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• v.32 no.4
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• pp.393-403
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• 2021

A comprehensive knowledge of the wind flow in hilly terrains is of great interest in many engineering applications, be it wind energy distribution for suitable site selection for wind farms, pollution dispersion, forest fire propagation or agrometerological studies. Several researchers have shown that wind flow over a hilly terrain may be significantly different when compared with the wind flow over a flat terrain. Complex hilly terrains may alter the wind speed to a great extent. Therefore, this effect of terrain must be properly assessed by designers and planners to arrive at a proper wind flow distribution. This paper reviews the work done in this area over the past three decades. Wind flow over two-dimensional hills and two-dimensional escarpments investigated in wind tunnels by various researchers is presented in this paper.

• Wind and Structures
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• v.26 no.2
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• pp.99-114
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• 2018

Due to shortage of land and architectural aesthetics, sometimes the buildings are constructed as unconventional in plan. The wind force acts differently according to the plan shape of the building. So, it is of utter importance to study wind force or, more specifically wind pressure on an unconventional plan shaped tall building. To address this issue, this paper demonstrates a comprehensive study on mean pressure coefficient of 'E' plan shaped tall building. This study has been carried out experimentally and numerically by wind tunnel test and computational fluid dynamics (CFD) simulation respectively. Mean wind pressures on all the faces of the building are predicted using wind tunnel test and CFD simulation varying wind incidence angles from $0^{\circ}$ to $180^{\circ}$ at an interval of $30^{\circ}$. The accuracy of the numerically predicted results are measured by comparing results predicted by CFD with experimental results and it seems to have a good agreement with wind tunnel results. Besides wind pressures, wind flow patterns are also obtained by CFD for all the wind incidence angles. These flow patterns predict the behavior of pressure variation on the different faces of the building. For better comparison of the results, pressure contours on all the faces are also predicted by both the methods. Finally, polynomial expressions as the sine and cosine function of wind angle are proposed for obtaining mean wind pressure coefficient on all the faces using Fourier series expansion. The accuracy of the fitted expansions are measured by sum square error, $R^2$ value and root mean square error.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.5
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• pp.1785-1790
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• 2010

To study the vortex induced vibrations the wind tunnel and the two story shear building were designed and built. The wind tunnel was designed to generate the wind speed up to 24 m/s, and the building was designed to have the two lowest natural frequencies within the range of the vortex frequencies generated by the wind tunnel. The resonance behaviors by the locking-on phenomena were observed during the wind tunnel tests of the shear building with the cylinder attached. From the locking-on phenomena observed it is found that the effects of the amplitudes and the frequencies of the cylinders should be considered on the forces generated by the vortex shedding.

• Wind and Structures
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• v.1 no.3
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• pp.225-241
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• 1998

The high-rise supporting towers of long-span suspension and cable-stayed bridges commonly comprise a pair of slender prisms of roughly square cross-section with a center-to-centre spacing of from perhaps 2 to 6 widths and connected by one or more cross-ties. The tower columns may have a constant spacing as common for suspension bridges or the spacing may reduce towards the top of the tower. The present paper is concerned with the aerodynamics of such towers and describes an experimental investigation of the overall aerodynamic forces acting on a pair of square cylinders in two-dimensional flow. Wind tunnel pressure measurements were carried out in smooth flow and with a longitudinal intensity of turbulence 0.10. Different angles of attack were considered between $0^{\circ}$ and $90^{\circ}$, and separations between the two columns from twice to 13 times the side width of the column. The mean values of the overall forces proved to be related to the bias introduced in the flow by the interaction between the two cylinders; the overall rms forces are related to the level of coherence between the shedding-induced forces on the two cylinders and to their phase. Plots showing the variation of the force coefficients and Strouhal number as a function of the separation, together with the force coefficients spectra and lift cross-correlation functions are presented in the paper.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.745-750
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• 2007

This paper presents investigation of topographic effects over isolated 3-dimensional hills through wind tunnel experiments in a boundary layer wind tunnel. Topographic models having five different slopes of $5.71^{\circ},\;11.31^{\circ},\;16.70^{\circ},\;21.80^{\circ}$, and $26.57^{\circ}$, which were based on KBC(2005), were taken into account in the study. The maximum topographic factor and the range of topographic effect from the experiment were compared with those from worldwide major codes and standards, such as ASCE-7-02, AS/NZS-1170.2:2002, ISO4354(1997), and KBC(2005). From the comparison of major codes and standards, in the vertical region of topographic effect, the gentler the slope was. the more different the topographic factors and ranges of topographic effect were, but the steeper the slope was, the more similar they were. It was found from the experimental study that the region of topographic effect in the slope in the across wind direction was greater than the regions of major codes and standard. Also, the gentler the slope was. the larger the topographic factor from the experiment was than the factors of major codes and standards.