基于风洞试验的超高层建筑涡激共振危险性研究

发布时间：2018-01-21 01:19

本文关键词： 超高层建筑涡激共振涡激振动风洞试验多自由度气弹模型气动外形　出处：《武汉大学》2014年博士论文　论文类型：学位论文

【摘要】：随着超高层建筑高度的大幅增加,其低频、轻质、小阻尼的结构特性越来越突出,在强风作用下发生涡激共振的危险性越来越大。由于超高结构的涡激共振是一种大幅度、高强度的近似简谐振动,在抗风设计时必须考虑其发生的可能性和发生后的危险性。但目前结构风工程界对各种体型的超高层建筑发生涡激共振的危险性和危害性还认识不足,相关的研究不够全面、深入。本文针对600m以上的超高层建筑,通过风洞试验和理论分析系统地研究典型超高层建筑在各种风场中和各种风向角下涡激共振锁定的激发机制和发生概率,研究其共振锁定发生后的响应水平。同时研究超高层建筑体型及偏心对涡激共振锁定的发生和响应幅值的影响,并进一步研究局部气动措施对涡激共振的控制效果。具体说来,本文进行了以下几方面的工作： 1.对比分析了单自由度和多白由度气弹模型涡振响应和气弹参数的差异,指出了差异的根本原因,提出了多自由度气弹模型改进设计方法,在此基础上,设计制作了3个方截面、2个长方形截面、1个三角形、1个六边形、1个实际拟建高楼等多自由度模型和部分相应单自由度模型,通过风洞试验,测得了各模型在不同的Sc数、气动外形、偏心率、风场粗糙度下的涡振响应位移(或加速度)和表面风压。 2.识别分析了各模型的气动阻尼和气动刚度参数。构建了气动阻尼与结构阻尼比、结构高宽比及斯科拉顿数的关系,建立了考虑多因素的气动阻尼比的改进经验评估公式；分析了气动刚度的变化规律,建立了考虑气动刚度和峰值参数的涡振响应改进评估模型。 3.通过同步的测压与测响应MDOF模型试验,从频率改变量和流固相位关系的角度,给出了涡振响应位移时程不稳定的根本原因,解释了长期以来风工程界早就觉察但一直无法给出原因的现象。在此基础上,通过对涡振时各种气弹参数的分析,提出了基于极值峰因子和频率改变量联合决定的共振发生概率评估模型,划分了共振、似共振和不共振的界限,可以用其计算得到不同条件下共振与不共振发生的概率。 4.分析了既有实际高层建筑的体型特点,并从气动外形方面对其进行了分类。通过一系列气动外形优化的气弹模型试验,分析了几种典型气动外形的改变对涡振响应的影响,并结合一拟建实际828m高楼的多自由度模型风洞试验结果,评价了复杂气动外形下气弹效应对实际建筑涡振响应的影响。
[Abstract]:With the increase of the height of super high-rise buildings, the structural characteristics of low frequency, light weight and small damping become more and more prominent. The risk of vortex-induced resonance under the action of strong wind is more and more serious, because the vortex-induced resonance of ultra-high structure is a kind of approximate harmonic vibration with large amplitude and high intensity. In the design of wind resistance, the possibility of occurrence and the risk after occurrence must be considered. However, at present, the danger and harmfulness of vortex-induced resonance of super-tall buildings of various shapes are not well understood in the field of structural wind engineering. The related research is not comprehensive and in-depth. This paper is aimed at the super high-rise buildings above 600m. Through wind tunnel test and theoretical analysis, the excitation mechanism and occurrence probability of Vortex resonance locking of typical super-tall buildings in various wind fields and various wind direction angles are systematically studied. At the same time, the effect of the shape and eccentricity of super-tall building on the occurrence and response amplitude of the vortex-induced resonance locking is studied. Furthermore, the control effect of local aerodynamic measures on vortex-induced resonance is further studied. Specifically, the following work has been done in this paper: 1. The differences of vortex vibration response and Aeroelastic parameters between the single degree of freedom model and the multiple degree of freedom model are analyzed, and the root cause of the difference is pointed out. The improved design method of the multi-degree of freedom Aeroelastic model is put forward. Three square cross-sections, two rectangular sections, one triangle, one hexagonal, one practical high-building multi-degree of freedom model and some corresponding single-degree of freedom model are designed and manufactured, and the wind tunnel test is carried out. The vortex-vibration response displacement (or acceleration) and surface wind pressure were measured under different SC numbers, aerodynamic profile, eccentricity, wind field roughness. 2. The aerodynamic damping and aerodynamic stiffness parameters of each model are identified and analyzed. The relationship between aerodynamic damping and structural damping ratio, ratio of height to width of structure and Scoreton number is established. An improved empirical evaluation formula for aerodynamic damping ratio considering multiple factors is established. The variation law of aerodynamic stiffness is analyzed and an improved evaluation model of vortex-vibration response considering aerodynamic stiffness and peak parameters is established. 3. Through the simultaneous MDOF model test of pressure measurement and measurement response, the fundamental cause of the instability of vortex vibration response displacement time history is given from the angle of the relationship between the frequency change and the fluid-solid potential. This paper explains the phenomenon that wind engineering has been aware of for a long time but has not been able to give the cause. On this basis, the analysis of various Aeroelastic parameters during vortex vibration is carried out. A probability evaluation model of resonance based on the combination of extreme peak factor and frequency change is proposed, and the boundaries of resonance, quasi-resonance and non-resonance are divided. It can be used to calculate the probability of resonance and non-resonance under different conditions. 4. The physical characteristics of the existing high-rise buildings are analyzed and classified from the aspect of aerodynamic shape. A series of aero-elastic model tests of aerodynamic shape optimization are carried out. The influence of several typical aerodynamic shapes on the response of vortex vibration is analyzed, and the wind tunnel test results of a proposed 828m tall building with multi-degree of freedom model are combined. The effect of Aeroelastic effect on the vortex-vibration response of buildings with complex aerodynamic profiles is evaluated.
【学位授予单位】：武汉大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TU973.213

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