A wind engineering research field laboratory, which consists of a full-scale low-rise building and two towers, has been constructed by Tongji University near Shanghai Pudong International Airport to study the characteristics of near-ground wind field and wind pressure on low-rise buildings. The full-scale building, whose roof pitch could be adjusted ranging from 0° to 30°, is 10 m in length, 6 m in width and 8 m in eave's height. It is employed to study the wind pressure on the gable roof of low-rise building with different roof pitches. This paper explicitly and concretely discusses the filed facility, data measurement system, data acquisition system, and tap location to provide references for related researchers. Besides, two pieces of time-histories of ten-minute-length wind pressures are analyzed at 0° and 20° roof pitches respectively to compare with those of a wind tunnel test on a rigid model of 1 : 30 scale. The results show that the tendency for the mean and fluctuating wind pressure distributions between the two kinds of tests is nearly similar.
According to the survey of wind hazard, the main reason resulting in casualties and property losses is the damage and collapse of the low-rise buildings in villages and small towns during tropical storm periods [
At present, the available method for this research is based mainly on wind tunnel test, while the field measurement is seldom employed for its high investment of resources and time taking. On the other hand, there is a gap between the results of field measurement and wind tunnel test due to reasons such as the inaccurate simulation in wind tunnel of the Reynolds effect and high turbulence at atmosphere surface layer. Therefore, field measurement has become the most reliable way to master the action mechanism of wind loads and is the most authoritative reference to modify the method of physical and numerical modeling [
In the last four decades, there have been a number of notable full-scale studies of wind loads on low-rise buildings, which permit researchers to make appropriate comparisons with wind tunnel measured data and numerical simulation results. In the early 1970s, the BRE (Building Research Establishment) in the UK commenced a program of full-scale measurements on a special constructed experimental building with two stories in Aylesbury, England [
Field measurement laboratories of low-rise buildings.
Name | Site | Size (length |
Roof pitch | Feature |
---|---|---|---|---|
Aylesbury test | UK | 13.3 m |
Variable | Adjustable roof pitch between |
TTU experiment | USA | 9.1 m |
|
Rotatable building |
Silsoe (steel frame) | UK | 24.3 m |
|
Variable eave styles |
Silsoe (cube) | New Zealand | 6 m |
|
Adjustable cube pitch |
HNU building | China | 6 m |
|
Removable building |
TJU building | China | 10 m |
Variable | Adjustable roof pitch between |
Another field measurement research in China was developed by Tongji University from the year 2008. The building used for field measurement was built at the coast of China near Shanghai Pudong International Airport. The plane size of the building is 10 m × 6 m and the eave height is 8 m. The main feature of this building is that the pitch of roof can be adjusted from 0° to 30° by using the lifting device. The architectural appearance of the pitch-adjustable building was designed according to the typical characteristics of the low-rise buildings in villages in South China.
Pudong New District in Shanghai is an area where strong wind, especially strong typhoons, frequently occurs each year. A field laboratory has been set up by State Key Laboratory of Disaster Reduction in Civil Engineering of Tongji University to study the turbulence characteristics of near-ground wind and wind loads on full-scale low-rise buildings. The field laboratory is located in a flat area close to the Yangtze River’s estuary and near Shanghai Pudong International Airport (see Figure
Measurement site.
The terrain of test building.
The steel structure test building has three single-story internal rooms, 3 m, 2.5 m, and 1.5 m in height for each story, respectively. The recording equipment is housed on the middle floor. The test building features an adjustable roof pitch from 0° to 30°. Figure
Full-scale low-rise test building.
Pitch of 0°
Pitch of 30°
Figure
Elevating system.
Sliding guiding device.
Lifting devices.
Active device
Passive device
Two types of pressure transducers are used to measure surface pressures of the test building’s roof. They are all developed by Kunshan Shuangqiao Sensor Measurement Controlling Co. Ltd. Of these, 94 microdifferential pressure sensors, CYG1220, are mounted to study the wind pressure without rain, and 20 other diaphragm pressure sensors, CYG1516, are installed under the roof to study the wind-rain-induced effects on pressure. The photos of two kinds of transducers are shown in Figure
Specifications of the pressure transducer.
Specifications | CYG1220 | CYG1516 |
---|---|---|
Range | 0 ~ |
0 ~ |
Response frequency | More than 20 Hz | More than 200 Hz |
Input voltage | DC 24 V | DC 24 V |
Output signal |
|
|
Rated accuracy | Less than 0.5% FS | Less than 0.5% FS |
Compensation temperature |
|
|
Photos of two types of pressure sensors.
CYG 1220
CYG 1516
Figure
Pressure measurement system of CYG 1220.
Figure
Pressure measurement system of CYG 1516.
An industrial computer with 2G RAM and 2.4 GHz coprocessor is used for data acquisition. Two conversion boards supplied by National Instruments Corporation are used to capture the incoming signals, and each one is an 80-channel and 16-bit A/D board. Cycling scanning has been adopted for the minimum requirement of dynamic responsibility, which is completely satisfied with the data collection for 160 channels. The sampling frequency of each transducer is 20 Hz. Zero calibration of all the transducers is checked before data collection. Figure
Photo of adapter.
Photo of industrial computer.
According to previous field measurement and wind tunnel tests, the extreme negative pressure usually occurs at the windward corner during oblique wind direction for gable roof buildings, and the gradient of pressure is larger than those at other locations. From the wind rose of Shanghai, shown in Figure
Wind rose of Shanghai.
Layout of pressure taps on the surface of roof (
Photos of tap locations at corner roof.
Inside
Outside
The field laboratory also consists of two self-supporting steel towers. The photos of the towers are shown in Figure
Photos of towers.
10 m tower
40 m tower
The other tower is 40 m in height and about 35 m far from the building in the north. To study the turbulence characteristics of strong wind near ground, eight anemometers were installed on the tower at the height of 10, 20, 30, and 40 m, respectively. The types of the anemometers are R. M. Young 81000, R. M. Young 85106, and R. M. Young 05305V, and their sampling frequencies are 20, 4, and 20 Hz, respectively. The arrangement of anemometers is displayed in Figure
Specifications of anemometers.
Specifications | R.M. Young 81000 | R.M. Young 85106 | R.M. Young 05350 V | |
---|---|---|---|---|
Wind speed | Range |
|
|
|
Resolution | 0.01 m/s | 0.1 m/s | — | |
Accuracy | ±0.05 m/s ( |
±0.1 m/s ( |
0.2 m/s | |
Wind direction | Range (horizontal) |
|
|
|
Range (vertical) | ± |
0 | 0 | |
Resolution |
|
|
— | |
Accuracy | ± |
± |
± |
|
Sampling frequency | 4–32 Hz (20 Hz used) | 1 Hz | 20 Hz | |
Working temperature | − |
− |
− |
The arrangements of anemometers (unit: m).
Another industrial computer type PXI-1031 is used for data acquisition by National Instruments Corporation, and the machine combines a 4-slot PXI backplane with a structural design that has been optimized for maximum usability in a wide range of applications. A DC power from National Instruments is used to provide the power through the DC input connector on the rear panel of the chassis. The PXI-1031 backplane is a 32-bit PCI, so the 64-bit compact PCI cards operate in 32-bit mode in this chassis.
A wind tunnel test rigid model was in 1/30 scale based on the full-scale test building to compare the wind pressure on the roof between full-scale experiment and wind tunnel tests. The test was performed in TJ-2 Boundary Layer Wind Tunnel in Tongji University. The wind tunnel cross-section is 3 m in width, 2.5 m in height, and 15 m in length. Wind field condition corresponding to roughness exposure B in the Chinese code was simulated in the wind tunnel at a length scale of 1/30. Table
Cases of field measurement (FM) and wind tunnel (WT) test.
Parameters | FM1 | FM2 | WT1 | WT2 |
---|---|---|---|---|
Test type | Full-scale | Full-scale | Wind tunnel | Wind tunnel |
Scale proportion | 1 : 1 | 1 : 1 | 1 : 30 | 1 : 30 |
Roof pitch |
|
|
|
|
Mean wind speed at eave (m/s) | 8.58 | 9.97 | 9.02 | 9.02 |
Mean wind direction |
|
|
|
|
Turbulence intensity | 0.233 | 0.221 | 0.247 | 0.241 |
Sampling frequency (Hz) | 20 | 20 | 312.5 | 312.5 |
Sample time and data length | 10 min | 10 min | 38.4 s | 38.4 s |
12000 | 12000 | 12000 | 12000 |
The surface pressure on the body is usually expressed in the form of a nondimensional pressure coefficient [
For comparison, Figure
Contours of mean wind pressure coefficients.
Case of field measurement (FM1)
Case of wind tunnel (WT1)
Case of field measurement (FM2)
Case of wind tunnel (WT2)
Contours of RMS wind pressure coefficients.
Case of field measurement (FM1)
Case of wind tunnel (WT1)
Case of field measurement (FM2)
Case of wind tunnel (WT2)
Pudong New District in Shanghai is an area that strong wind, especially strong typhoons, frequently occurs each year. Therefore, a field laboratory was constructed by State Key Laboratory of Disaster Reduction in Civil Engineering of Tongji University to study the turbulence characteristics of near-ground wind field and wind effects on full-scale low-rise gable-roof buildings. The field laboratory described in this paper is the first project in China for wind effects based on the measurement on a fixed low-rise building. The full-scale building’s roof pitch angle could be adjusted from 0° to 30°, which facilitates the study on the wind effects of low-rise building with different pitches. The details of the project are explicitly and concretely given to provide reference for related researchers. More importantly, results of the field measurement can allow researchers to make a comparison with those from physical and numerical modeling to provide guidance for the improvement of the wind tunnel test as well as computational fluid dynamic (CFD) technology.
This project is jointly supported by the Ministry of Science and Technology of China (Grants no. SLDRCE09-B-06 and SLDRCE08-A-03), and the National Natural Science Foundation (nos. 51178352 and 90715040), which are gratefully acknowledged.