**7. The wind tunnel test on the multi-bay model under the turbulent boundary layer flow**

In most cases, the horn shaped membrane structure is used as the multi-bay type. The number of horn unit depends on the scale of the building and the building uses. Therefore, this chapter focuses on the multi-bay model of 3×3. This test was carried out to clarify about the basic characteristics of the wind pressure coefficient of the multi-bay horn-shaped membrane roof.

### **7.1. Outline of tests**

This test used the same facilities and the same turbulent flow as the stand-alone model shown in chapter 5. A model scale of a horn unit was 30cm x 30cm and the number of unit was 3 wide, 3 bays, and the models ware made from acrylic (see figure 19 and 20). This experimental model was only one type of rise-span ratio, namely h/L=0.2.

Wind Tunnel Tests on Horn-Shaped Membrane Roof Under the Turbulent Boundary Layer http://dx.doi.org/10.5772/54180 139

**Figure 19.** Experimental models and measuring points on the multi-bay models

**Figure 18.** Peak wind pressure coefficient which was obtained from wind tunnel tests on open type of the stand-

In most cases, the horn shaped membrane structure is used as the multi-bay type. The number of horn unit depends on the scale of the building and the building uses. Therefore, this chapter focuses on the multi-bay model of 3×3. This test was carried out to clarify about the basic characteristics of the wind pressure coefficient of the multi-bay horn-shaped membrane roof.

This test used the same facilities and the same turbulent flow as the stand-alone model shown in chapter 5. A model scale of a horn unit was 30cm x 30cm and the number of unit was 3 wide, 3 bays, and the models ware made from acrylic (see figure 19 and 20). This experimental model

**7. The wind tunnel test on the multi-bay model under the turbulent**

alone mode

**boundary layer flow**

138 Wind Tunnel Designs and Their Diverse Engineering Applications

**7.1. Outline of tests**

was only one type of rise-span ratio, namely h/L=0.2.

**Figure 20.** The photo of models on the multi-bay model; one type of h/L model which was made from acrylic plastic.

#### **7.2. Results of mean wind pressure coefficient on the multi-bay model**

Distributions of mean wind pressure coefficient on each model are shown in figure 21 and 22. The distributions were changed by wind direction as same as stand-alone models. Forcus‐ ing on the enclosed model, the positive pressure were shown around the valley of the roof. On the other hand, in the open type, windward side show positive pressure.

These results of open type were obtained approximately the same results with the standalone model of open type. On the other hand, as for the enclosed type, results were different from the stand-alone model. Specifically, focusing on the rise-span ratio 0.2, the value of the wind pressure coefficient around the middle of model was smaller than the stand alone models.

**Figure 21.** Mean wind pressure coefficient which were obtained from wind tunnel tests on enclosed type of the multibay mode

**Figure 22.** Mean wind pressure coefficient which were obtained from wind tunnel tests on open type of the multi-bay mode

#### **7.3. Results of fluctuating wind pressure coefficient on the multi-bay model**

Distributions of fluctuating wind pressure coefficient on each model are indicated in figure 23 and 24. The fluctuating wind pressure coefficients indicated on multi-bay model almost the same as that on stand-alone model. The enclosed model showed value of 0.6 or more over the whole area of the roof. But the open type showed comparatively large value of approximately 0.8 on the only windward side.

**Figure 21.** Mean wind pressure coefficient which were obtained from wind tunnel tests on enclosed type of the multi-

**Figure 22.** Mean wind pressure coefficient which were obtained from wind tunnel tests on open type of the multi-bay

Distributions of fluctuating wind pressure coefficient on each model are indicated in figure 23 and 24. The fluctuating wind pressure coefficients indicated on multi-bay model almost the

**7.3. Results of fluctuating wind pressure coefficient on the multi-bay model**

bay mode

140 Wind Tunnel Designs and Their Diverse Engineering Applications

mode

**Figure 23.** Fluctuating wind pressure coefficient which were obtained from wind tunnel tests on enclosed type of the multi-bay mode

**Figure 24.** Fluctuating wind pressure coefficient which were obtained from wind tunnel tests on open type of the multi-bay mode

#### **7.4. Results of peak wind pressure coefficient on the multi-bay model**

The maximum peak wind pressure coefficients are shown in figure 25, and the minimum peak wind pressure coefficients are shown in figure 26. These distributions were changed by wind direction. Furthermore, these wind pressure coefficients around the top of roof indicated the maximum negative value. And these results were smaller than the stand-alone models.

**Figure 25.** Maximum peak wind pressure coefficient which were obtained from wind tunnel tests on the multi-bay model

**Figure 26.** Minimum peak wind pressure coefficient which were obtained from wind tunnel tests on the multi-bay model

### **8. Conclusions**

In this paper, the characteristics of the wind pressure coefficients on the horn-shaped mem‐ brane roof were presented using wind tunnel tests with the turbulent boundary layer flow. Particularly, the followings are clarified that;


Furthermore, the representative distributions of the wind pressure coefficient were shown on each parameter.
