某火车站两种张拉膜结构风荷载分布及对比分析研究

Wind Load Distribution and Comparative Analysis of Two Kinds of Tensile Membrane Structures in a Railway Station

摘要: 以某火车站两种不同型式的张拉膜结构(流线型椭球面膜结构和上翘式弧形膜结构)为研究对象，研究两种不同型式的张拉膜结构各自典型测点的风压系数随风向角变化的规律；在典型风向角下屋盖表面各自的风压分布规律的异同；两种不同张拉膜结构风压分布规律的异同。结果表明：对测点而言，椭球面膜结构上表面典型测点的风压系数随风向角在迎风面时为正，转到背风面时为负，下表面中心测点的风压系数随风向角的变化过程中一直为负；弧形膜结构典型测点的风压系数波动范围较小，随风向角的变化不明显；在任意风向角下，椭球面膜结构风压系数的绝对值大于弧形膜结构。对风压分布规律而言，椭球面膜结构在105˚和195˚风向角下，迎风面受压，背风面受吸，下表面最大负压系数出现在结构中部；弧形膜结构在0˚风向角下迎风面受压，背风面受吸，而在270˚风向角下，结构表面以吸力为主下表面最大负压系数出现在结构边缘。通过对比分析，两种不同型式的张拉膜结构在风顺着矢跨比较大的方向吹来时，都表现为迎风面受压，背风面受拉；在风顺着两种张拉膜结构矢跨比最小的方向吹来时，椭球面膜结构下表面的迎风面以负压为主，背风面以正压为主，而弧形膜结构下表面以正压为主。

Abstract: Taking two different types of tensioned membrane structures (streamline ellipsoidal membrane structure and upturned curved membrane structure) of a certain railway station as the research object, the paper studies the wind pressure coefficients of two different types of tensioned mem-brane structures at their typical measuring points; the similarities and differences of the respective wind pressure distributions on the upper surface of roof in the typical wind directions; and the sim-ilarities and differences of the wind pressure distributions of two different tensile membrane structures. The results show that for the measuring point, the wind pressure coefficient of the typi-cal measuring point on the upper surface of the ellipsoidal membrane structure is positive when the wind direction angle is on the windward surface, and negative when it turns to the leeward sur-face. In the arbitrary wind direction, center selected taps of bottom surface are under negative pressure; the wind pressure coefficient of the typical measuring point of the curved membrane structure has a small fluctuation range, and the change with the wind direction angle is not obvious; the absolute value of the wind pressure coefficient of the ellipsoidal mask structure is larger than that of the curved membrane structure in the arbitrary wind direction. Regarding the distribution of wind pressure, the ellipsoidal membrane structure is at 105˚ and 195˚ wind direction angles, the windward side is compressed and the leeward side is sucked, and the maximum negative pressure coefficient of the lower surface appears in the middle of the structure; under the wind of 0˚ in direc-tion, the windward side of the curved membrane structure is compressed and the leeward side is lifted up. At a wind direction of 270˚, the surface of the structure is dominated by suction. The maximum negative pressure coefficient appears at the edge of the structure. When the wind blows from the direction where the ratio of the height to the span of two kinds of structures is largest, the windward side of them is compressed and the leeward side is lifted up; when the wind blows from the direction with the smallest height-span ratio of the two structures, the wind pressure coefficient of the windward side of the bottom surface of the ellipsoidal membrane structure is basically nega-tive, the wind pressure coefficient of the leeward side is basically positive, and the wind pressure coefficient of the bottom surface of the upturned curved membrane structure is basically positive.