摘要:
大跨轻钢工业建筑是典型的风致敏感结构,容易出现风致灾害问题。风荷载和建筑物外形密切相关,由于使用工艺的要求,工业建筑中通常需设置长悬挑雨篷,然而在现行规范GB 50009—2012《建筑结构荷载规范》和GB 51022—2015《门式刚架轻型房屋钢结构技术规范》中并无两侧带悬挑雨篷结构所对应的风荷载体型系数,因此选择合理的风荷载体型系数成为抗风设计的关键。以两侧带通长雨篷的工业建筑为研究对象,基于Fluent有限元软件,分别研究了雨篷悬挑长度和倾角对建筑典型位置风荷载体型系数的影响,并与GB 50009—2012和GB 51022—2015进行比较,最后给出了带悬挑雨篷结构的抗风设计建议。研究结果表明:雨篷悬挑长度对建筑迎风面雨篷上部墙面及雨篷的体型系数影响显著;迎风面雨篷上部墙面的风荷载体型系数在正倾角下随着雨篷长度的增加由正变负,在负倾角下均为正值;全屋面及背风面体型系数均为负值,受雨篷悬挑长度的影响不大;雨篷倾角除对雨篷及迎风面雨篷上部墙面体型系数影响较大外,对其余各个位置的影响不大;雨篷倾角为正时,迎风面雨篷上部墙面体型系数为负值且随着雨篷倾角的增大而减小,雨篷受到的风吸力随着倾角增大而增大;雨篷倾角为负时,迎风面雨篷上部墙面的体型系数为正值,且随着倾角的增大而增大,雨篷受到的风吸力随着倾角的增大而减小。通过与现行规范GB 50009—2012和GB 51022—2015《门式刚架轻型房屋钢结构技术规范》进行对比,除雨篷长度在8 m且倾角为0°时,迎风面雨篷体型系数为-1.37,与GB 50009—2012中表8.3.1第16项封闭式带雨篷结构中迎风面雨篷体型系数-1.4较为接近外,其他位置的风荷载体型系数相差较大;对于其他雨篷悬挑长度及倾角,所对应的结构各处风荷载体型系数与现行规范相比均有较大差异,在设计中应特别注意。
Abstract:
Long-span light-gauge steel industrial buildings are typical wind-induced sensitive structures, which are prone to wind-induced disasters. The wind load is closely related to the shape of the building. Due to functional requirements,long cantilevered awnings are usually set in industrial buildings. There is no corresponding shape coefficients of wind loads of the cantilevered awning structure on both sides in the current code Load Code for the Design of Building Structures (GB 50009—2012) and Technical Code for Steel Structure of Light-Weight Building with Gabled Frames (GB 51022—2015). Therefore, selecting a reasonable shape coefficient of wind loads becomes the key to wind resistance design. Taking the industrial building with through-length awnings on both sides as the research background, the influence of different overhang lengths and inclination angles of the awnings on the shape coefficients of wind loads at typical positions of the building based on the software Fluent. It was compared with the current code GB 50009—2012 and GB 51022—2015, and provided the wind resistance design suggestions of structure with overhanging awnings. The results indicated that: the length of awning had a significant effect on the upper wall of the awning and the shape coefficient of the awning. The shape coefficient of wind loads on the upper wall of the windward awning changed from positive to negative with the increase of awning length at positive inclination angle, and was positive at negative inclination angle. The shape coefficients of the whole roof and the leeward side were negative, and the length of awning had little effect. The angle of the awning had great influence on the shape coefficient of the awning and the upper wall of the awning on the windward side, but had little influence on the other positions. When the awning angle was positive, the upper wall shape coefficient of the awning was negative and decreased with the increase in the awning angle, and the wind suction of the awning increased with the increase in the awning angle. When the angle of the awning was negative, the shape coefficient of the upper wall of the awning was positive and increased with the increase in the angle, and the wind suction of the awning decreased with the increase in the angle. By comparing with the current codes, GB 50009—2012 and GB 51022—2015, the shape coefficient of the windward awning was -1.37 when the awning length was 8 m and the angle was 0°. The shape coefficient of eaves on the windward side was close to -1.4 in item 16 of table 8.3.1 of Load Code for the Design of Building Structures, but the shape coefficients of wind load at other positions were different. And for other awning lengths and angles corresponding to the structure of the shape coefficients of wind loads were different from the current codes, enough attention should be paid to the design.
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