| ABSTRACT:With the rapid development of economy and city construction in China, lots of industrial workshops have been built in the southeast coastal area.These roof structures are completely immersed in the surface boundary layer, interference from other similar buildings is very significant. There are many factors to effect the interference effect, and each factor has great variability. At present, there is less study on interference effects among this kind of roof buildings. With the wind tunnel tests, this paper investigates the influence mechanism of interference effect among flat roof buildings.Firstly, wind load characteristics of the single long-span flat roof structure are studied. The influence of geometry dimension on wind pressure is discussed. The results show that the ratio of length to width and height to width has significant influence on the flow separation and wind pressure at the windward edge of the roof.Then, the effects of many factors on wind interference of the building in the group corner, edge, and center,such as the row number and column number of building group, the ratio of building length to width and high to width, and spacing are analyzed. Results show that, number of row and column in the building group has great influence on the mean wind pressure coefficient on the roof. And there is a great difference between the3rows3columns building group and1row,2rows,1column,2columns buildings group. But the number of row and column has less influence on the unfavorable peak pressure, where the interference factor is between0.9to1.1. The ratio of length to width and high to width of the building has significant influence on the peak pressure. Interference factor of peak pressure in different building roof area can reach0.6～1.4. Small spacing (2h,1.5h) has a significant shielding effect on mean wind pressure coefficient, peak pressure and the wind force coefficients. Interference factor is as low as0.2, and the wind load is reduced of80%.Finally, on the basis of the above research, taking buildings groups with1row3columns,3rows1column and3rows3columns as typied building, this paper studies the drag coefficient and lift coefficient with the change of the spacing. And then the flow pattern between the buildings is analyzed. The results show that2.5h and8h spacing is the limit value of three kinds of flow patterns. For three typical spacing, law of wind force coefficients of building group with3rows3columns are similar to these of3rows1column when the wind direction is0degree. The eigen-modes and spectrum of fluctuating pressure also verify the influence of the spacing distance on three flow pattern among the buildings. |
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