scholarly journals Research on Snow Load Characteristics on a Complex Long-Span Roof Based on Snow–Wind Tunnel Tests

2019 ◽  
Vol 9 (20) ◽  
pp. 4369 ◽  
Author(s):  
Guolong Zhang ◽  
Qingwen Zhang ◽  
Feng Fan ◽  
Shizhao Shen
Keyword(s):  
Wind Tunnel ◽  
Basic Characteristic ◽  
Wind Tunnel Test ◽  
Experimental System ◽  
Similarity Criteria ◽  
Wind Tunnel Tests ◽  
Snow Load ◽  
Long Span ◽  
Characteristic Modes ◽  
Snow Distribution

A considerable number of studies have been carried out for predicting snowdrifts on roofs over the years. However, few studies have focused on snowdrifts on complex long-span roofs, as the complex shape and fine structure pose significant challenges. In this study, to simplify the calculation requirements of snow load on such roofs, work was conducted to decompose the snowdrift on a complex roof into snowdrifts on several simple roofs. First, the snow–wind tunnel test similarity criteria were investigated based on a combined air–snow–wind experimental system. Thereafter, with reference to the validated experimental similarity criteria, a series of snow–wind tunnel tests were performed for snowdrifts on a complex long-span structure under the conditions of different inflow directions. Finally, based on empirical orthogonal function (EOF) analysis, the snowdrifts on the complex roof were decomposed into basic characteristic distribution modes, including snowdrifts caused by the local and overall roof forms. The snow distribution under a specific inflow direction could be derived from the weighted combination of the basic characteristic modes, based on the wind direction coefficients. Therefore, it is possible for the snow load on a complex roof to be estimated preliminarily based on the snow distributions on several simple roofs.

scholarly journals Experimental Study of Interference Effects of a High-Rise Building on the Snow Load on a Low-Rise Building with a Flat Roof

2021 ◽  
Vol 11 (23) ◽  
pp. 11163
Author(s):  
Qingwen Zhang ◽  
Yu Zhang ◽  
Ziang Yin ◽  
Guolong Zhang ◽  
Huamei Mo ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Snow Accumulation ◽  
Interference Effects ◽  
Wind Tunnel Tests ◽  
Snow Load ◽  
Building Roof ◽  
High Rise ◽  
High Rise Building ◽  
Snow Distribution ◽  
Flat Roof

To explore the interference effects of a high-rise building on the snow load on a low-rise building with a flat roof, a series of wind tunnel tests were carried out with fine silica sand as a substitute for snow particles. The effects of the height of the interfering building and the distance between buildings on the snow distribution of the target building under three different wind directions were studied. The snow depth on the target building roof and the mass of particles blown off from the target building were measured during the wind tunnel tests, and the results showed that the snow distribution of the target building roof tends to be uniform when the interfering building is located upstream of the target building due to the shelter effect. When the interfering building is on the side of the target building, the snow distribution of the target building tends to be more uneven, because the interfering building increases the friction velocity on the target building roof near the interfering building. However, when the interfering building is located downstream of the target building, there will be an amplification effect of snow accumulation, and the snow distribution on the target building roof is nearly the same as that of the isolated condition. Under each wind direction, the interference effect of the snow load increases with the increase of the building height and the decrease of the building spacing. Therefore, the influence of the surrounding buildings on the snow distribution of the building roof cannot be ignored and should be considered in the structure design.

scholarly journals Wind Tunnel Tests and Numerical Simulations of Wind-Induced Snow Drift in an Open Stadium and Gymnasium

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Xintong Jiang ◽  
Zhixiang Yin ◽  
Hanbo Cui
Keyword(s):  
Wind Tunnel ◽  
Numerical Simulations ◽  
Wind Direction ◽  
Interference Effect ◽  
Mutual Interference ◽  
Wind Tunnel Tests ◽  
Direction Angle ◽  
Long Span ◽  
Snow Drift ◽  
Snow Distribution

A long-span sports centre generally comprises multiple stadiums and gymnasiums, for which mutual interference effects of wind-induced snow motion are not explicitly included in the specifications of various countries. This problem is addressed herein by performing wind tunnel tests and numerical simulations to investigate the snow distribution and mutual interference effect on the roofs of long-span stadiums and gymnasiums. The wind tunnel tests were used to analyse the influences of the opening direction (0°, 90°, 180°, and 270°) and spacing (0.3 L, 0.5 L, 1 L, 1.5 L, 2 L, and 2.5 L, where L is the gymnasium span) of the stadium and gymnasium. The wind tunnel tests and numerical simulations were used to analyse the influence of the wind direction angle (from 0° to 315°, there are a total of eight groups in 45° intervals). The following results were obtained. The stadium opening had a significant effect on the snow distribution on the surface of the two structures. An even snow distribution was obtained when the stadium opened directly facing the gymnasium, which corresponded to the safest condition for the structures’ surfaces. As the spacing between the buildings increased, the interference effect between the two structures was reduced. The interference was negligible for a spacing of 2 L. The stadium had the most significant amplification interference effect on the gymnasium for a wind direction angle of 45°, which was extremely unfavourable to the safety of the structure. The most favourable wind direction angle was 270°, where there were both amplification interference and blockage interference.

scholarly journals Wind-Induced Phenomena in Long-Span Cable-Supported Bridges: A Comparative Review of Wind Tunnel Tests and Computational Fluid Dynamics Modelling

2021 ◽  
Vol 11 (4) ◽  
pp. 1642
Author(s):  
Yuxiang Zhang ◽  
Philip Cardiff ◽  
Jennifer Keenahan
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Tunnel ◽  
Careful Analysis ◽  
Wind Effects ◽  
Wind Tunnel Tests ◽  
Long Span Bridges ◽  
Long Span ◽  
Comparative Review ◽  
Dynamics Modelling

Engineers, architects, planners and designers must carefully consider the effects of wind in their work. Due to their slender and flexible nature, long-span bridges can often experience vibrations due to the wind, and so the careful analysis of wind effects is paramount. Traditionally, wind tunnel tests have been the preferred method of conducting bridge wind analysis. In recent times, owing to improved computational power, computational fluid dynamics simulations are coming to the fore as viable means of analysing wind effects on bridges. The focus of this paper is on long-span cable-supported bridges. Wind issues in long-span cable-supported bridges can include flutter, vortex-induced vibrations and rain–wind-induced vibrations. This paper presents a state-of-the-art review of research on the use of wind tunnel tests and computational fluid dynamics modelling of these wind issues on long-span bridges.

Wind Tunnel Experimental Research on Flutter Stability of Liujiaxia Bridge

2013 ◽  
Vol 361-363 ◽  
pp. 1105-1109
Author(s):  
Chun Sheng Shu
Keyword(s):  
Wind Tunnel ◽  
Critical Velocity ◽  
Experimental Research ◽  
Wind Tunnel Test ◽  
Suspension Bridge ◽  
Wind Tunnel Tests

Liujiaxia Bridge is a truss stiffening girder suspension bridge which span is 536m, and it is the narrowest suspension bridge with the same scale, so the problems of flutter stability are prominent. Results of wind tunnel test show that its critical velocity cannot meet the requirements without any aerodynamic measures. Based on above considerations, seven kinds of aerodynamic measures are proposed, respectively wind tunnel tests are conducted. The results show that the program, in which the upper central stable board is 1.12m high and the under central stable board is 1.28m high, can meet the requirements. The results of this study provide some references to solving the problem of wind-resistant stability of narrow deck suspension bridge.

Videogrammetric Measurement for Model Displacement in Wind Tunnel Test

2011 ◽  
Vol 130-134 ◽  
pp. 103-107 ◽  
Author(s):  
Zheng Yu Zhang ◽  
Shui Liang Wang ◽  
Yan Sun
Keyword(s):  
Image Processing ◽  
Wind Tunnel ◽  
Wind Tunnel Test ◽  
Accurate Data ◽  
Exterior Orientation ◽  
Wind Tunnel Tests ◽  
Key Techniques ◽  
Transonic Wind Tunnel

It is crucial measuring position and attitude of model to gain the precise and accurate data in wind tunnel tests. The model displacement videogrammetric measurement (MDVM) system and its key techniques such as the exterior orientation with big rotation angles and large-overlap, mark points, image processing and calibration based on the known distances are therefore presented. The practice example in Asia's largest (2.4m) transonic wind tunnel has demonstrated the MDVM system and its key techniques are correct and feasible, and they have application value.

Flutter mitigation of a superlong-span suspension bridge with a double-deck truss girder through wind tunnel tests

2020 ◽  
pp. 107754632094615
Author(s):  
Yanguo Sun ◽  
Yongfu Lei ◽  
Ming Li ◽  
Haili Liao ◽  
Mingshui Li
Keyword(s):  
Wind Tunnel ◽  
Damping Ratio ◽  
Suspension Bridge ◽  
Wind Tunnel Tests ◽  
Long Span Bridges ◽  
Long Span ◽  
Upper Deck ◽  
Torsional Damping ◽  
And Control ◽  
Wind Induced Vibration

As flutter is a very dangerous wind-induced vibration phenomenon, the mitigation and control of flutter are crucial for the design of long-span bridges. In the present study, via a large number of section model wind tunnel tests, the flutter performance of a superlong-span suspension bridge with a double-deck truss girder was studied, and a series of aerodynamic and structural measures were used to mitigate and control its flutter instability. The results show that soft flutter characterized by a lack of an evident divergent point occurred for the double-deck truss girder. Upper central stabilizers on the upper deck, lower stabilizers below the lower deck, and horizontal flaps installed beside the bottoms of the sidewalks are all effective in suppressing flutter for this kind of truss girder. By combining the structural design with aerodynamic optimizations, a redesigned truss girder with widened upper carriers and sidewalks, and double lower stabilizers combined with the inspection vehicle rails is identified as the optimal flutter mitigation scheme. It was also found that the critical flutter wind speed increases with the torsional damping ratio, indicating that the dampers may be efficient in controlling soft flutter characterized by single-degree-of-freedom torsional vibration. This study aims to provide a useful reference and guidance for the flutter design optimization of long-span bridges with double-deck truss girders.

scholarly journals Wind Tunnel Tests of Wind-Induced Snow Distribution for Cubes with Holes

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Xintong Jiang ◽  
Zhixiang Yin ◽  
Hanbo Cui
Keyword(s):  
Wind Tunnel ◽  
Snow Depth ◽  
Structural Safety ◽  
Windward Side ◽  
Leeward Side ◽  
Wind Tunnel Tests ◽  
Maximum Snow Depth ◽  
Adjacent Structures ◽  
Significant Difference ◽  
Snow Distribution

The nonuniform distribution of snow around structures with holes is extremely unfavorable for structural safety, and the mechanism of wind-snow interaction between adjacent structures with holes needs to be explored. Therefore, a wind tunnel simulation was performed, in which quartz particles with an average particle size of 0.14 mm as snow particles were used, and cubes with dimensions of 100 mm × 100 mm × 100 mm each containing a hole with the size of 20 mm × 20 mm were employed as structures. Firstly, the quality of a small low-speed wind tunnel flow field was tested, and then the effects of hole orientation (hole located on the windward side, leeward side, and other vertical sides) and absence of holes on the surface of a single cube were studied. Furthermore, the effects of different hole locations (respectant position, opposite position, and dislocation) and relative spacing (50 mm, 100 mm, and 150 mm) on the surfaces of two cubes and the snow distribution around them were investigated. It was concluded that the presence and location of hole had a great influence on snow distribution around cubes. Snow distribution was favorable when hole was located on the other vertical sides of the test specimen. The most unfavorable snow distribution was obtained when the holes on the two-holed sides of the cubes were respectant with a maximum snow depth coefficient of 1.4. A significant difference was observed in the snow depths of two sides of cubes when holes were dislocated. When two holes were respectant, surrounding snow depth was decreased, and the maximum snow depth on model surface area was increased with the increase of spacing. Wind tunnel tests on holed cubes provided a reference for the prediction of snow load distribution of typical structures with holes.

Wind-Induced Responses Study and Wind-Resistant Design of Super-Long-Span Cable-Membrane Roof Structure of Shenzhen Baoan Stadium

2011 ◽  
Vol 71-78 ◽  
pp. 666-672
Author(s):  
Wen Bo Sun ◽  
Qing Xiang Li ◽  
Han Xiang Chen ◽  
Wei Jian Zhou
Keyword(s):  
Numerical Calculation ◽  
Wind Tunnel ◽  
Dynamic Response ◽  
Membrane Structure ◽  
Wind Tunnel Test ◽  
Scale Model ◽  
Induced Responses ◽  
Design Codes ◽  
Long Span ◽  
Roof Structure

In this paper, the system and the design philosophy of wheel-spoke cable-membrane structure of Baoan Stadium is introduced firstly. And then the study of wind tunnel test on 1:250 scale model is mainly presented, together with the numerical calculation of the wind dynamic response. Finally, the wind-resistant design of the roof structure based on the results of wind tunnel test and the foreign design codes is generally introduced.

scholarly journals Aerodynamic study of a suspension bridge deck by CFD simulations, wind tunnel tests and full-scale observations

2021 ◽  
Vol 1201 (1) ◽  
pp. 012007
Author(s):  
I. Kusano ◽  
E. Cheynet ◽  
J. B. Jakobsen ◽  
J. Snæbjörnsson
Keyword(s):  
Wind Tunnel ◽  
Wind Tunnel Test ◽  
Suspension Bridge ◽  
Aerodynamic Characteristics ◽  
Full Scale ◽  
Navier Stokes ◽  
Cfd Simulations ◽  
Wind Tunnel Tests ◽  
Long Span Bridges ◽  
Wide Range

Abstract Assessing the aerodynamic characteristics of long-span bridges is fundamental for their design. Depending on the terrain complexity and local wind conditions, episodes of large angles of attack (AoA) of 15° may be observed. However, such large AoAs ( above 10°) are often overlooked in the design process. This paper studies the aerodynamics properties of a flow around a single-box girder for a wide range of AoAs, from –20° to 20°, using numerical simulations. The simulations are based on a 2D unsteady Reynolds-averaged Navier–Stokes (URANS) approach using the k − ω SST turbulence model with a Reynolds number of 1.6 × 105. Numerically obtained aerodynamic static coefficients were compared to wind tunnel test data. The CFD results were generally in good agreement with the wind tunnel tests, especially for small AoAs and positive AoAs. More discrepancies were observed for large negative AoA, likely due to the limitation of modelling 3D railings with 2D simulations. The simulated velocity deficit downstream of the deck was consistent with the one measured in full-scale using short-range Doppler wind lidar instruments. Finally, the Strouhal number from the CFD simulations were in agreement with the value obtained from the full-scale data.

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