INFLUENCE OF BASEBOARD HEIGHT ON WIND FORCE OF SCAFFOLDS AT BUILDING EDGE

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Hiroki Takahashi ◽  
Katsutoshi Ohdo ◽  
Kazuo Ohgaki
Keyword(s):  
Wind Tunnel ◽  
Wind Tunnel Test ◽  
Design Guidelines ◽  
Construction Sites ◽  
Wind Force ◽  
Force Coefficient ◽  
Building Components ◽  
Modern Building

When scaffolds are installed in construction sites, their resistance against wind force needs to be calculated. Japanese design guidelines require a specific scaffold resistance against wind force, but such rules and regulations are applicable solely to old-style scaffolds. A number of risks are inherent in the existing guidelines. First, new-style scaffolds are used in construction sites without practitioners knowing whether the design guidelines are appropriate for modern building components. Second, scaffolds are set near buildings, but workers are unaware of the effect of the wind force at the building edge. Finally, conventional designs feature the use of baseboards as scaffold components. While considering the aforementioned issues, a wind tunnel test was carried out as part of this study to examine the wind force exerted on scaffolds erected near a building edge. The parameters used in the test were baseboard height and the distance from the building edge. From the results, when the distances between the building’s center and the scaffold’s center are 180 mm, the wind force is high. Additionally, when the baseboard height is 130 mm, the wind force is high. This study examined the correction number for the wind force coefficient of scaffolds with baseboards that were positioned at building edge. Whenever the scaffolds were set near the building edge, we needed to revise the wind force coefficient of the scaffolds.

WIND TUNNEL TEST OF SCAFFOLDS SET WITH WALL CONNECTERS WITH BASEBOARD HEIGHT AS A PARAMETER

2016 ◽  
Vol 3 (1) ◽  
Author(s):  
Hiroki Takahashi ◽  
Katsutoshi Ohdo
Keyword(s):  
Wind Tunnel ◽  
Wind Tunnel Test ◽  
Wind Load ◽  
Design Guidelines ◽  
Industrial Safety ◽  
Construction Sites ◽  
Wind Force ◽  
Force Coefficient ◽  
Safety And Health ◽  
Design Calculations

The Japanese Industrial Safety and Health Law were revised in March 2009 to introduce new measures by which to prevent accidental falls in the construction industry. As part of this revision, authorities established regulations on the provision of guard rails, toe boards, mesh sheets, and other components in appropriate positions on scaffolds. When scaffolds are set in construction sites, their strength against wind force needs to be calculated. Japanese design guidelines regulate the strength of scaffolds against wind force; however, the design guidelines were written with old-style scaffolds in mind. It is not known whether the design guidelines are appropriate for new-style scaffolds. At the construction sites, the scaffolds connect to structures through the use of wall connecter, to keep scaffolds from falling down. The wind load that acts on the scaffolds was supported by the wall connecter at the construction sites. On the other hand, in conventional designs, a baseboard is used on construction sites. In this study, to set scaffolds at construction sites while using baseboard height as a parameter, we performed a wind tunnel test to examine the wind load that acts on scaffolds that have been set with wall connecters. The wind tunnel device has a total length 74,900 mm, while the device interior is 2,300 mm wide and 2,000 mm high. The load sell to set the wall connecter was used to measure wind load. The models, each of which was 1/10 in size, were used on scaffolds at general construction sites. The scaffolds were three stories high and one span wide. A baseboard was situated on one side of the long face of the scaffolds. The wind speed was set at a uniform flow of 10 m/s, because the wind force coefficient of a cylinder is stable at this speed. The characteristic length was positioned 5 mm along the diameter of a leg member. The Reynolds number was approximately 3.5 × 103. From our results, the wind force coefficient was found to increase as the baseboard height increased. With regard to efficient scaffold design, calculations of the wind force coefficient should therefore consider baseboard height.

INFLUENCE OF BASEBOARD HEIGHT ON RESISTANCE TO WIND FORCE OF SCAFFOLDS AT WINDWARD SIDE OF BUILDINGS

2016 ◽  
Vol 3 (2) ◽  
Author(s):  
Hiroki Takahashi ◽  
Mizuki Aoki ◽  
Katsutoshi Ohdo ◽  
Kazuo Ohgaki
Keyword(s):  
Construction Industry ◽  
Wind Tunnel Test ◽  
Design Guidelines ◽  
Industrial Safety ◽  
Windward Side ◽  
Construction Sites ◽  
Wind Force ◽  
Force Coefficient ◽  
Safety And Health ◽  
The Relationship

The Japanese Industrial Safety and Health Law was revised in March 2009 to introduce new measures by which to prevent accidental falls in the construction industry. As part of this revision, regulations on the installation of guard rails, toe boards, mesh sheets, and other components in appropriate positions on scaffolds were established. When scaffolds are installed in construction sites, their resistance against wind force needs to be calculated. Japanese design guidelines stipulate a specific scaffold resistance against wind force, but such regulations are applicable to conventional scaffolds. The problem with outdated regulations is that scaffolds are used during building construction without practitioners knowing whether the existing guidelines are suitable for new-style scaffolds. Accordingly, this study was conducted a wind tunnel test to examine the wind force exerted on building scaffolds, with the parameters being baseboard height and distance between scaffolds and a building. The relationship between the wind force coefficient of the scaffolds and baseboard height was proportional only on the scaffolds. As the distance between the scaffolds and the building lengthened, however, the relationship between the parameters reflected a steeper curve as baseboard height increased. Whenever the scaffolds were set near the building, negative pressure acted on the scaffolds as a consequence of the downwind structure. This study was examined the correction factor of the wind force coefficient of the scaffolds.

WIND TUNNEL TEST FOR CALCULATING WIND FORCES ON SCAFFOLDS WITH BASEBOARD HEIGHT AS A PARAMETER

2014 ◽  
Vol 1 (1) ◽  
Author(s):  
Hiroki Takahashi ◽  
Katsutoshi Ohdo ◽  
Seiji Takanashi
Keyword(s):  
Wind Tunnel ◽  
Construction Industry ◽  
Wind Tunnel Test ◽  
Industrial Safety ◽  
Design Codes ◽  
Health Law ◽  
Wind Force ◽  
Force Coefficient ◽  
Safety And Health ◽  
Current Design

The Japanese Industrial Safety and Health Law was revised in March 2009 to introduce new measures concerning accidental falls in the construction industry. This revision mandates the use of guard rails, handrails, and other scaffold components. The wind load criteria and structural specifications of scaffolds are regulated by current design codes. Nevertheless, these provisions do not necessarily comply with the newly incorporated legal requirements because they apply to old-style scaffolds. This study examined the wind force on scaffolds by wind tunnel test, with baseboard height used as a parameter. The wind force coefficient of one story of scaffolds was calculated. Wind force coefficient increased as baseboard height increased. The wind force on the scaffolds equipped with baseboards is 9.2 times that on the scaffolds without baseboards. The baseboard must be greater than or equal to 15 cm to satisfy regulation requirements. The wind force coefficient of scaffolds with a 15 cm baseboard is 1.5 times that of the scaffolds without a baseboard. In scaffold design, baseboard height should be considered to guarantee a suitable wind force coefficient.

Wind tunnel test on mean wind forces and peak pressure acting on ellipsoidal nacelles of wind turbine

2021 ◽  
pp. 0309524X2110445
Author(s):  
Hiroshi Noda ◽  
Takeshi Ishihara
Keyword(s):  
Wind Tunnel ◽  
Wind Turbine ◽  
Peak Pressure ◽  
Wind Tunnel Test ◽  
Load Case ◽  
Wind Force ◽  
Pressure Coefficients ◽  
Force Coefficients ◽  
Design Load ◽  
Mean Pressure

Mean wind forces and peak pressures acting on ellipsoidal nacelles are investigated by wind tunnel tests. The wind force coefficients of the ellipsoidal nacelles for the wind turbine design and the peak pressure coefficients for the nacelle cover design are proposed based on the experimental data. The wind force coefficients are expressed as functions of yaw angles. The proposed formulas are compared with Eurocode, Germanischer Lloyd and ASCE7-16. It is found that the mean wind force coefficients for the wind turbine nacelles are slightly underestimated in Eurocode. The equivalent maximum and minimum mean pressure coefficients are proposed for use in Design Load Case 6.1 and Design Load Case 6.2 of IEC 61400-1. The peak pressure coefficients are derived using a quasi-steady theory. The proposed equivalent maximum and minimum mean pressure coefficients are much larger than those specified in Germanischer Lloyd.

WIND LOADS AND WIND-INDUCED BUCKLING OF OPEN-TOPPED OIL-STORAGE TANKS IN VARIOUS ARRANGEMENTS

2014 ◽  
Vol 1 (1) ◽  
Author(s):  
Yasushi Uematsu ◽  
Jumpei Yasunaga ◽  
Choongmo Koo
Keyword(s):  
Wind Tunnel ◽  
Wind Loading ◽  
Storage Tanks ◽  
Wind Force ◽  
Force Coefficient ◽  
Oil Storage ◽  
Internal Surfaces ◽  
Circumferential Distribution ◽  
Wind Pressures ◽  
Gap Spacing

Wind force coefficients for designing open-topped oil-storage tanks in various arrangements have been investigated under experiments involving a wind tunnel and a buckling analysis of the tanks. In the wind tunnel experiment, the wind pressures were measured simultaneously at many points both on the external and internal surfaces of a rigid model for various arrangements of two to four tanks. The effects of arrangement and gap spacing of tanks on the pressure distribution are investigated. The buckling of tanks under static wind loading is analyzed by using a non-linear finite element method. A discussion of the effect of wind force distribution on the buckling behavior follows. The authors provided a model of circumferential distribution of wind force coefficient on isolated open-topped tanks in their previous paper. This paper proposes a model of wind-force coefficient for plural tanks in various configurations by modifying the model for isolated tanks.

Test Research on Aerodynamic Interference Effect on Aerostatic Coefficients of Main Beam in Parallel Bridge

2012 ◽  
Vol 178-181 ◽  
pp. 2131-2134
Author(s):  
Jie Wang ◽  
Jian Xin Liu
Keyword(s):  
Wind Tunnel ◽  
Drag Coefficient ◽  
Wind Tunnel Test ◽  
Lateral Force ◽  
Main Beam ◽  
Interference Effects ◽  
Force Coefficient ◽  
Long Span ◽  
Rigid Frame ◽  
Aerodynamic Interference

Against the problem of the aerodynamic interference effects on aerostatic coefficients between parallel continuous rigid frame bridges with high-pier and long-span, the aerodynamic interference effects on aerostatic coefficients of main beam in the parallel long-span continuous rigid frame bridges were investigated in details by means of wind tunnel test. The space between the two main beams and wind attack angles were changed during the wind tunnel test to study the effects on aerodynamic interferences of aerostatic coefficients of main beam. The test got aerostatic coefficients of 10 conditions. The research results have shown that the aerodynamic interference effects on aerostatic coefficients of main beam in parallel bridges can not be ignored. The aerodynamic interference effects on parallel bridge main beam is shown mainly as follows: The drag coefficient of main beam downstream dropped and the drag coefficient of main beam upstream changed but not change significantly. There are also the aerodynamic interference effects of lateral force coefficient and torque coefficient between the main beams upstream and downstream. The effects upstream are smaller and the effects downstream are larger.

The Study of Wind Load Characteristics of Round Earth Building Roof Based on Wind Tunnel Test and Numerical Simulation

2011 ◽  
Vol 243-249 ◽  
pp. 5171-5176
Author(s):  
Xing Qian Peng ◽  
Kun Shao ◽  
Zhi Fei Gao
Keyword(s):  
Numerical Simulation ◽  
Wind Tunnel ◽  
Wind Tunnel Test ◽  
Wind Load ◽  
Building Roof ◽  
Building Model ◽  
World Heritage List ◽  
The World ◽  
Load Characteristics ◽  
Modern Building

Since the "Fujian Earth Building" was on the list of the world heritage list, the protecting work of Earth Building gets more and more important. This paper adopts the method combining wind tunnel test and numerical simulation, using CFD software to establish the representative building model of round monolayer Earth Building and get the wind load characteristics in different wind direction. And the wind tunnel tests confirmed the reliability of simulated results. The results provide reference to the protection and wind-resistant design for Earth Building and modern building of Earth Building mode.

scholarly journals Comparison of Wind Tunnel Test Data for Low-Rise Buildings with Main Wind Force Resisting System Design Procedures

Buildings ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 342
Author(s):  
S. M. Ashfaqul Hoq ◽  
Johnn P. Judd
Keyword(s):  
Wind Tunnel ◽  
Test Data ◽  
Reliability Index ◽  
Wind Tunnel Test ◽  
External Pressure ◽  
Base Shear ◽  
Wind Force ◽  
Design Procedures ◽  
Design Wind Speed ◽  
The Difference

The adequacy of the directional and envelope procedures for the design of the main wind force resisting system is not well understood. The purpose of this study is to evaluate the directional and envelope procedures based on wind tunnel test data for a set of low-rise enclosed buildings with gable-shaped roofs in open terrain (Exposure C). The base shear force and the conditional reliability index are used to determine the adequacy of the procedures. The base shear was compared to the design base shear in each direction based on the horizontal component of the wind load on the wall and roof. The reliability index, β conditional on the occurrence of the design wind speed was computed for a range of system capacities. The main findings are (1) the directional procedure produced a larger design base shear compared to the envelope procedure, primarily due to the difference in external pressure coefficients, (2) the directional procedure provided a higher β, and (3) the envelope procedure provided a β that did not meet the standard target β equal to 3.0 for the main wind force resisting systems with low variability in capacity, but neither procedure met the standard target β for the main wind force resisting systems with high variability in capacity.

scholarly journals Static Wind Load Evaluation under Steady-State Wind Flow for 2-Edge Sloped Box Girder by Using Wind Tunnel Test

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Hoyeop Lee ◽  
Jiho Moon
Keyword(s):  
Wind Tunnel ◽  
Slope Angle ◽  
Wind Tunnel Test ◽  
Lateral Force ◽  
Wind Load ◽  
Wind Force ◽  
Aerodynamic Stability ◽  
Box Girder ◽  
Load Evaluation ◽  
Cable Stayed Bridges

The two-edge box girder has been widely used as a stiffened girder in cable-stayed bridges. However, such girders have weakness in aerodynamic stability. To improve its aerodynamic stability, some previous researchers have given slope to the edge box instead of installing additional attachments to aerodynamically stabilize the bridge. For wind load design, an angle of attack (AOA) has to be considered. However, the effect of AOA has not been studied for sloped box girder yet. In the present study, the effect of AOA on the static wind load coefficient was investigated for 2-edge sloped box girder. A series of wind tunnel tests was performed by varying the box slope angle from 0° to 17° where AOA was set from −10° to 10°. Results showed that the lateral wind force is considerably reduced with the increase of the box slope angle except the case with the physical angle of 8°–11°. For practical AOA range, the box slope should be larger than 15° to minimize the aerodynamic static lateral force on the girder.

Open Rotor Design Strategy: From Wind Tunnel Tests to Full Scale Multi-Disciplinary Design

2015 ◽  
Author(s):  
Jonathan Vlastuin ◽  
Clément Dejeu ◽  
Anthony Louet ◽  
Jérôme Talbotec ◽  
Ingrid Lepot ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
High Speed ◽  
Design Methodology ◽  
Wind Tunnel Test ◽  
Design Strategy ◽  
Design Guidelines ◽  
Full Scale ◽  
Wind Tunnel Tests ◽  
Open Rotor ◽  
Definition Of

For several years, Safran has been involved in the design and optimization of contra rotating open rotors. This innovative architecture is known for allowing drastic reduction in fuel burn, but its development is facing complex technological challenges such as acoustics, aerodynamics, and weight penalty due to the mechanical complexity of an Open Rotor. Since 2010, Safran has been developing the experimental test bench HERA (1/5 mock-up scale) to improve the understanding of the complex aerodynamics and acoustics phenomena involved in the counter rotating propellers configuration. Isolated and installed low speed and high speed wind tunnel campaigns, including PIV measurements have been extremely helpful in defining design guidelines for full scale open rotor specification. These tests have been used as CFD feed-back among other purposes. An iterative process involving CFD optimization (in close collaboration with Cenaero) and wind tunnel test campaigns has been developed over the last 4 years and has led to the definition of an innovative design strategy, which has been successfully tested during the process of the full scale counter rotating propellers design for the SAGE2 ground test demonstrator engine. This phase has evidenced the absolute necessity of a multi-disciplinary design method when it comes to full scale and “rig-ready” design. Ensuring high propulsive efficiency and at the same time, minimizing the acoustic level, while maintaining severe mechanical constraints such as weight, inertia and proper dynamic positioning under control, requires a dedicated and integrated “all inclusive” design process. The aim of this paper is to present the design methodology and some of the wind tunnel tests results carried out over the last 4 years, which have led to the definition of a novel multidisciplinary design methodology that involves CFD, FEM and acoustics.

Sign in / Sign up

Export Citation Format

Share Document