Wind Load Characteristics Of Open Long-span Flat Roof

Open long-span flat structures are light, flexible and they also possess small damping factor, therefore wind load becomes one of the main loads instructural design. Relative to the closed large-spanstructures, the research of open type on wind resistance is very lack, its mechanism and wind load characteristics have not been fully re-vealed. For this reason, based on the flat roof, the mechanism of open large-span roof are systematic studied.Finally this paper gave the suggested designing windload values of mainstructure and envelope structure.This paper includes the following aspects:1. This paper has Completed the wind tunnel test of model O、A、B1、B2、C and D, It should be pointed out that, due to the interference of pressure measurement system, the wind pressure data of top and bottom surface can’t be get at a time,so the upper and lower surface pressure data are obtained by two experiments.2. The mechanism ofwind load of columnar vortex is determined in this paper.It turned out that:windward wall is the major factor to affect the characteristics of colum-nar vortex.Columnar vortex with windward wall has large influence and strength;on the premise of windward wall,open wall will enhance the mean and fluctuating wind pres-sure of open edge and open angle. Columnar vortex without winfward wall has a small-scale influence and low strength, by this time, leeward wall is the major influen-cing factor,lower surfacepresents positive pressure with a leeward wall.3. The mechanism of wind load of conical vortex is determined in this paper.It turned out that:windward wall is the major factor to affect the characteristics of conical vortex. Conical vortex with windward wall has large influence and strength; open wall will enhance the mean and fluctuating wind pressure of open edge and open angle. Conical vortex without winfward wall has a small-scale influence and low strength, by this time, leeward wall is the major influencing factor,conical vortex on upper surface are enhanced and lower surfacepresents positive pressure with a leeward wall.4. The suggested designingwindload values of mainstructureand envelope structure are given. Based on the fully enclosed type and fully opentype, the suggested designing windload values of mainstructure and envelope structure are given in this paper,and Compared with the relevantspecification.