# On Wind-Induced Fatigue of Curtain Wall Supporting Structure of a High-Rise Building
## 2 Research Methodology  
### Wind Tunnel Test  
Researchers have used a combination of wind tunnel tests and finite element analysis to study wind-induced fatigue of buildings [11; 12]. The test model for high-rise buildings refers to a rigid body model made of ABS (Acrylonitrile Butadiene Styrene) material, with sufficient strength and stiffness. The principles of wind tunnel tests (including similar guidelines, scale, amount of shielding, number of principle directions, etc.) can be found in the literature [13]. The model is geometrically similar to real objects in appearance, the building prototype includes two towers, A and B, and a commercial center C. Tower A is about 280 m high and tower B is about 200 m high; the scale ratio is 1:300, and the height of tower A of the building model is about 0.93 m. There were many air pressure holes on the outside of the model, to maintain an airtight state, and the inside was hollowed out and installed with air pressure pipes. Finally, the model was placed in a section of the wind tunnel test, and the wind pressure pipe was connected to an electronic pressure scanning valve to measure the surface wind pressure of the main building and envelope structure. In the test, the model was fixed on the turntable of the wind tunnel, which could rotate to simulate different wind directions. A total of 969 measuring points were arranged in the model, in order to measure wind pressure distribution on the building surface, podium surface, canopy surface, and building roof (Figure 2).  
Figure 1: Research process.  
Figure 2: Distribution of wind tunnel experimental models. (**A**) tower A, 280 m high, the scale ratio is 1:300; (**B**) tower B, 200 m high, the scale ratio is 1:300; (**C**) commercial center.  
This test was carried out in the HD-3 atmospheric boundary layer wind tunnel of Hunan University. Focusing on the main building, the wind tunnel test simulated the load-carrying capability of a single building, and ignoring surrounding main buildings and terrain, the wind tunnel model was placed on the turntable in the wind tunnel test section to measure data. It aimed to measure the wind pressure on the structures surface in 24 wind directions (rotation counterclockwise at a vertical plane, 0\({}^{\circ}\), 0\({}^{\circ}\)\(\sim\)360\({}^{\circ}\), and the wind direction angle was 15\({}^{\circ}\) to the north elevation of building A). During the test, each measurement point was sampled for 30 s, the sampling frequency was 312.5 Hz, the height of the test reference point was 110 cm, and wind velocity at the test reference point was controlled to 7.5 m/s (Figure 3).  
The wind tunnel test and related calculations refer to the \"Load Code for the design of building structures\"(GB50009-2012). For each measurement point, 10,000 wind pressure data were recorded. According to the following formula, the model's time histories of wind pressure obtained from the pressure test can be converted into the prototype's time histories of wind pressure [14]:  
\[\frac{P_{f}}{P_{sj}}=\frac{P_{m}}{P_{sy}} \tag{1}\]  
where \(P_{m}\) is the time history data obtained from the pressure test; \(P_{f}\) is the time history data of wind pressure converted to actual conditions, \(P_{sj}\) is the actual incoming flow wind pressure, and \(P_{sy}\) is the experimental incoming flow wind pressure.