| Summary: | 博士 === 國立成功大學 === 建築學系 === 87 === Abstract
Seismic forces strongly affect R.C. Buildings. On the other hand, as the buildings get higher and higher, or if the buildings were made of lighter material, wind forces become more and more important.
This study was conducted experimentally in water table and in boundary layer wind tunnel facilities respectively. Two scaled-down plastic models were tested in the water table facility to visualize the environmental flow, one model with an opening and the other without. The Reynolds number was 900 and five flow angles (0°，30°，45°,60°,90°) were examined.
In the BLWT(Boundary Layer Wind Tunnel)facility two other scaled-down models were also tested to obtain the surface pressures on the models and there wind drag. Again, one model had an opening in the middle while the other had not. The Reynolds number was 28800 and the five flow angles were the same as those used in water table testing.
The results show that an opening in a building reduces the area of horseshoe vortex, reduces the area of leeward wake, increases the Karman vortex shedding frequency and makes the shedding more simultaneously, and reduces the building drag and the environmental effect. It reduces values of the leeward surface pressure on the building, too. But on the windward surface, the peak pressure is about the same for both cases while the surface pressures are redistributed by the opening.
When compared with the present building code, the result calculated from code is safer than that from experiment.That is the code gives a conservative design.
|
|---|
