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.

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.

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.

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.

scholarly journals Evaluation of Wind-Induced Response Bounds of High-Rise Buildings Based on a Nonrandom Interval Analysis Method

2018 ◽  
Vol 2018 ◽  
pp. 1-14
Author(s):  
Xianglei Wei ◽  
An Xu ◽  
Ruohong Zhao
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Wind Tunnel Test ◽  
Wind Load ◽  
Upper And Lower Bounds ◽  
Induced Response ◽  
Response Analysis ◽  
Analysis Method ◽  
High Rise ◽  
Interval Analysis Method

The traditional wind-induced response analysis of high-rise buildings conventionally considers the wind load as a stationary stochastic process. That is, for a certain wind direction angle, the reference wind speed (usually refers to the mean wind speed at the building height) is assumed to be a constant corresponding to a certain return period. Combined with the recorded data in wind tunnel test, the structural response can be computed using the random vibration theory. However, in the actual typhoon process, the average wind speed is usually time-variant. This paper combines the interval process model and the nonrandom vibration analysis method with the wind tunnel test and proposes a method for estimating the response boundary of the high-rise buildings under nonstationary wind loads. With the given upper and lower bounds of time-variant wind excitation, this method can provide an effective calculation tool for estimating wind-induced vibration bounds for high-rise buildings under nonstationary wind load. The Guangzhou East tower, which is 530 m high and the highest supertall building in Guangzhou, China, was taken as an example to show the effectiveness of the method. The obtained boundary response can help disaster prevention and control during the passage of typhoons.

Wind Load on Complex-Shape Building

2010 ◽  
Vol 163-167 ◽  
pp. 4389-4394
Author(s):  
Cheng Qi Wang ◽  
Zheng Liang Li ◽  
Zhi Tao Yan ◽  
Qi Ke Wei
Keyword(s):  
Numerical Simulation ◽  
Wind Tunnel ◽  
Negative Pressure ◽  
Complex Shape ◽  
Wind Tunnel Test ◽  
Wind Load ◽  
Negative Pressures ◽  
Windward Surface

Wind load on complex-shape building, the wind tunnel test and numerical simulation were carried out. The two technologies supplement each other and their results meet well. There are mainly positive pressures on the windward surface, negative pressures on the roof, the leeward surface and the side. Especially, negative pressure is higher in the leeward region of the building corner. Its effect induced by the shape of the complex-shape building is remarkable.

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.

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