【作者】 胡文松；

【导师】 徐赵东； 吕令毅；

【作者基本信息】 东南大学 ， 防灾减灾工程和防护工程， 2021， 硕士

【摘要】 大跨度开敞式罩棚被广泛应用于体育场等大型公共建筑中,由于该类结构具有自重轻、柔度大、阻尼小等特点,因此风荷载成为大跨度开敞式罩棚结构设计的主要控制荷载。进行大跨度开敞式罩棚抗风设计的首要前提是,需要获得该类罩棚结构的表面风压分布及体型系数。然而,对于大跨度屋盖开敞式、墙面和屋盖组合开敞式罩棚风荷载的研究较少,本文利用计算流体动力学方法,对大跨度屋盖开敞式罩棚、大跨度墙面和屋盖组合开敞式罩棚的风荷载进行了数值模拟,分析了不同风向角下大跨度开敞式罩棚表面风压特性及分布规律,并进行了相应的参数分析,给出了大跨度开敞式罩棚分区体型系数供设计参考。主要研究内容及结论如下:对大跨度环形结构屋盖开敞罩棚上的风荷载进行了数值模拟,研究了屋盖开敞罩棚表面风压分布规律,比较了屋盖开敞或封闭对罩棚表面风压分布的影响,分析了罩棚倾角、屋盖开敞率、罩棚和下部看台连接开缝高度等因素对罩棚表面风荷载大小及分布特性的影响。结果表明:屋盖开敞罩棚整体受向下的风荷载作用,考虑结构自重作用的叠加后,相比屋盖封闭罩棚对结构受力更为不利;罩棚倾角对屋盖开敞的罩棚表面风压分布影响较大,确定了两个“临界倾角”的范围以及罩棚表面风压随罩棚倾角变化的规律;屋盖开敞不宜过小,否则会引起罩棚整体受风荷载较大;罩棚和下部看台一定的开缝高度(开缝比为1/10)有利于减小背风侧罩棚向下的风荷载,而当开缝高度继续增大其减弱作用不再显著;给出了各工况下大跨度屋盖开敞罩棚表面分区体型系数建议取值供设计人员参考。对大跨度膜结构墙面和屋盖组合开敞式罩棚上的风荷载进行了数值模拟,研究了各风向角下罩棚表面平均风压分布规律,比较了屋盖开敞或封闭对罩棚表面风压分布的影响,分析了下部结构特性对罩棚表面风荷载大小及分布特性的影响。结果表明:墙面和屋盖组合开敞式罩棚主要受向上的风荷载,迎风边缘和屋盖开敞边缘的风荷载往往较大,45°风向角为最不利风向角工况;屋盖开敞或封闭对墙面和屋盖组合开敞的罩棚表面净风压分布影响较小;下部结构存在时迎风侧罩棚净负风压较不考虑下部结构工况大,其数值大0.4左右;给出了各工况下大跨度墙面和屋盖组合开敞式罩棚表面分区体型系数建议取值以供设计人员参考。更多还原

【Abstract】 The long-span open canopy structures are widely used in stadiums or other large-scale public buildings.These structures,with the characteristics of light mass,high flexibility and small damping,are sensitive to the wind loads,and thus the wind loads generally govern the structural design.The premise of wind resistance design of long-span open canopy structures is to obtain the wind induced pressure on canopy and the shape coefficient.However,the studies on the wind load of long-span canopy with roof opening or wall opening and roof opening are insufficient.In this paper,the numerical simulations of the wind load acting on the long-span canopy with roof opening and long-span canopy with wall opening and roof opening were conducted using the computational fluid dynamics.The characteristics and distribution of the wind induced pressure on the two types of long-span open canopies as well as the influence of some parameters were analyzed.The shape coefficients of the two types of long-span open canopies were given for providing reference in wind resistance design.The main research contents and conclusions are as follows,The numerical simulations of the wind load acting on the long-span ring canopy with roof opening were conducted.The wind induced pressure results of the open roof and closed roof cases were compared,the influences of the inclination angle of the canopy,the roof opening ratio,and the height of the joint between the canopy and the grandstand on the wind induced pressure distribution were analyzed.The results showed that the canopy with roof opening is subjected to the downward wind load,which is more unfavorable to the structural internal force than the canopy with roof closed considering of the self-weight of the structure.The range of two critical inclinations which are of vital influence were determined,and the variation law of the pressure distribution on the canopy with the inclination angle were discussed.The roof opening ratio should not be too small,otherwise the wind load on the canopy will be large.A certain joint height(joint ratio is 1/10)can greatly reduce the wind load on the canopy leeward,but the weakening effect is no longer significant when the joint height continues to increase.The shape coefficients of the long-span open canopy under various working conditions were given for the structural designers as a reference.The numerical simulations of the wind load acting on the long-span membrane canopy with wall opening and roof opening were conducted.The wind induced pressure results of the open roof and closed roof cases were compared,the influence of the substructure existence on the wind induced pressure distribution was analyzed.The results showed that the wind load on the canopy mainly is upward,and the wind load which the windward edge or roof opening edge on canopy are subjected to is large,the upward wind load on canopy in whole is the largest when the wind direction is 45°.Whether the roof opening is closed has a slight influence on the net pressure distribution on canopy.The net negative wind pressure on the canopy windward with substructure is larger than that without substructure,and the difference value of pressure coefficient is about 0.4.the shape coefficients of the long-span open canopy under various working conditions were given for the structural designers as a reference.更多还原