大型户外单立柱广告牌的风毁作用机理与抗风设计方法研究

As a typical wind vulnerability structure in urban area of China, the wind-induced disaster of large outdoor single-column billboards have been common in recent years, and have become the main weakness of urban wind disaster defenses . Due to the complex destruction mechanism and many influencing factors, the static and dynamic wind load effects, on this type of high-rise open-plates structure with such special aerodynamic shapes, have become the key problems need be solved urgently on the research of urban wind disaster at present. .The project aims at three kinds of wind failure modes, including panel connection damage, panel support system destroy and overall collapse under strong wind. By carrying out a series of synchronous multi-pressure scanning system (SM-PSS) measurement on surface of rigid model, high frequency force balance (HFFB) measurement at bases of rigid model, and dynamic responses of aero-elastic model in wind tunnel tests, the inherent mechanism and influencing factors of wind load effects and wind-destroyed modes of the billboard structure with different aerodynamic shapes and dynamic characteristics will be revealed systematically and comprehensively. Based on the theory of random vibration and wind engineering, the wind effect assessment theory on the large billboard structure are gradually established through three aspects: the local extreme net wind pressure characteristics of the panel, the wind load model on the panels, and the wind-induced response of the whole structure. This study will develop the wind resistance design methods and propose wind-resistant optimization measures, improve the wind resistance performance of large outdoor billboard facilities and provide technology parameters and theoretical basic for wind disaster prediction and risk control of wind vulnerable structures in urban area.

作为我国典型城市风易损性结构物，近年来大型单立柱多面广告牌在强风下的破坏屡见不鲜，已成为当前城市风灾害防御中的薄弱环节。这类特殊气动外形的开敞板式高耸结构的静力与动力风荷载效应的形成机理复杂、影响因素多，是目前城市风致灾变研究亟待解决的关键问题。.项目针对强风下面板连接破坏、面板支撑体系破坏、整体结构倒塌三种风灾破坏模式，通过开展刚性模型表面多点同步测压、基底天平测力和风振气动弹性模型风洞试验，系统和全面揭示不同气动外形、动力特征的广告牌结构风荷载效应与风毁模式的内在机理和影响因素；并结合随机振动及风工程理论，从面板的局部极值净风压特性、面板整体风荷载模型、整体结构风振响应规律三个层面，逐步建立大型广告牌结构的风效应评估理论；发展和完善广告牌结构的抗风设计方法，提出抗风优化措施。本项研究将提高大型户外广告牌设施抗风性能，并为该类城市风灾易损性结构的灾害预测和风险控制提供基础数据和理论依据。

随着中国城市化进程的快速发展，大型户外广告牌愈发普遍且外形多样。作为一类典型的风敏感结构，其强风导致的破坏及引发的次生灾害也逐渐引起了城市防灾管理的关注。既有国内外既有研究和规范都仅只给出了单面板广告牌的抗风设计方法。缺乏多面广告牌这类特殊开敞的板式高耸结构风荷载效应的系统研究。.项目针对面板在极值风压下的连接破坏，通过开展不同地貌下多点同步测压试验，考察了面板表面净风压分布的统计特征和分布规律；考虑风压的非高斯特性，给出了正/负极值的包络，提出了面板局部体型系数。结合POD风压场重构和Copula函数考虑风压极值的相关性，给出了面板连接破坏的易脆性评估方法。.项目针对面板支撑框架的破坏，基于刚性模型基底测力风洞试验，对面板顺风向、横风向、水平合力及基底扭矩等整体风力系数的平均值、均方根值、极值和功率谱进行了比较分析。研究风向角、间隙比、宽高比、面板夹角对风力系数的影响规律。分给出了最不利工况下面板的风压分布和风力体型系数。建立了多面板的面顺风向气动导纳函数、给出了水平风力和扭矩风力风荷载谱的建议公式；提出了减少面板风荷载的气动外形优化措施。.项目针对结构整体倒塌破坏，通过整体结构的气弹性模型测振风洞试验，研究了柔性单立柱广告牌结构的基底风振响应随风向角变化的规律和特征。综合刚性测力和气弹测振两阶段试验结果，提出了气动阻尼系数，风振计算的频域方法、等效风荷载计算理论方法。系统的建立了多面广告牌顺风向和扭转风振响应的理论计算方法。.项目基于上述不同气动外形参数的双面、三面、环形模型的共计146种工况的风洞试验和理论建模，分别从面板连接、面板支撑体系以及支撑立柱三个层面系统的开展了单立柱多面广告牌的风荷载效应研究。项目研究不仅为广告牌结构抗风设计规范中相关参数的修订，提供了详实的试验数据和重要的理论基础。也为大型户外独立柱广告牌运维监测、风灾预警和预测提供了重要技术依据。