开洞建筑风致内压响应的理论和试验研究

发布时间：2018-08-29 17:02

【摘要】：建筑由于使用功能要求或者在强风作用下门窗破坏而形成开孔时,会使结构内部风压骤然增大。历年的风灾调查显示,多数房屋围护结构的破坏(例如屋盖掀翻和墙面倒塌)是由于内外压共同作用所造成的。当开孔大小符合某些条件时,内压将产生强烈的共振效应使得内压脉动得到大幅提高,对围护结构安全极为不利。我国经常受台风影响的沿海地区存在着大量低矮房屋和大跨厂房,合理的估算结构所受的极值风荷载有利于提高这些建筑的抗风性能,减少恶劣风环境下的经济损失。本文结合理论分析和试验对不同形式开孔结构风致内压的动力特性及其影响因素、关键的孔口参数取值、风洞试验方法等方面展开了系统的研究。本文从理论上推导了单一开孔、开孔双空腔、以及迎风面多开孔情况下内压的非线性传递方程,并分别对其进行线性化。结合模型试验验证了各传递方程的准确性,并分析了开孔面积,内部容积,风速风向等对脉动内压均方根、Helmholtz共振频率以及等效阻尼比等动力特性参数的影响。提出了随机荷载作用下未知惯性系数和损失系数的理论识别方法,并分别给出这两个参数的建议取值。自行研制了扬声器激振装置用于内压响应的研究,该装置能够产生频率和幅值可调节的简谐和随机外压。通过大量模型的扬声器激振试验和风洞试验来验证所推导识别公式的准确性,并对影响这两个孔口特征参数取值的因素(包括：结构柔性,模型安装方法,湍流强度,来流风速风向,开孔面积和位置,内部容积等)进行了深入地考察。基于相似性准则分析了风洞试验时各种开孔形式下为保证试验模型与原型内压动力特性相似性模型应该满足的条件,提出了准确测试内压的试验方法,并指出风洞试验过程中可能导致内压响应测试误差的情况。综合分析了开孔面积,开孔位置,建筑内部容积,来流风速和湍流度,以及内部干扰等因素对内压脉动,等效阻尼比以及共振响应的影响。比较了内外压脉动均方根之比的几种简化预测方法的适用性,分析了方程中待定常数的物理意义及其可能的影响因素。以4种开洞形式下某沿海地区大跨超高单层厂房的实际工程为例进行内外表压力的风洞测试,得出其风荷载及内压峰值因子的分布规律,并与规范体型系数和峰值因子的建议值进行了比较,重点考察了纵墙端部区的受力情况,给出了对屋盖和墙面受力最不利的风向角和开洞工况,为该类结构合理设计提供参考。采用CFD数值技术对不同长跨比相同单一开孔厂房纵墙的内外表面平均风压进行模拟并与风洞试验结果比较,验证了数值风洞的有效性。探讨了厂房长度对纵墙内外表面风压系数的影响,同时还研究了厂房端部效应区的范围以及厂房长度增长对其的影响。
[Abstract]:The wind pressure inside the structure will suddenly increase when the windows and doors are damaged under the strong wind due to the function requirement of the building. Wind disaster surveys over the years show that most of the damage to the enclosure structure (such as roof overturning and wall collapse) is caused by the combined action of internal and external pressure. When the hole size meets some conditions, the internal pressure will produce a strong resonance effect, which will greatly improve the internal pressure pulsation, which is extremely unfavorable to the safety of the enclosure structure. There are a large number of low-rise buildings and long-span factories in coastal areas often affected by typhoons. Reasonable estimation of extreme wind loads on structures is conducive to improving the anti-wind performance of these buildings and reducing economic losses under severe wind conditions. In this paper, the dynamic characteristics of wind-induced internal pressure of different types of open-hole structures and its influencing factors, key orifice parameters, wind tunnel test methods and so on are systematically studied in combination with theoretical analysis and test. In this paper, the nonlinear transfer equations of internal pressure in the case of single hole, double cavity and multiple openings on the upwind surface are derived and linearized respectively. The accuracy of the transfer equations is verified by model tests. The effects of the opening area, internal volume, wind speed and wind direction on the dynamic characteristic parameters such as the resonance frequency of Helmholtz resonance and the equivalent damping ratio are analyzed. A theoretical identification method of unknown inertial coefficient and loss coefficient under random load is proposed, and the suggested values of these two parameters are given respectively. A loudspeaker excitation device is developed for the study of internal pressure response. The device can generate simple harmonic and random external pressure with adjustable frequency and amplitude. The accuracy of the derived identification formula is verified by a large number of model loudspeaker excitation tests and wind tunnel tests, and the factors affecting the parameters of the two orifice characteristics (including structural flexibility, model installation method, turbulence intensity, etc. Wind speed and wind direction, hole area and location, internal volume, etc. On the basis of similarity criterion, this paper analyzes the conditions that should be satisfied in wind tunnel test in various open hole forms to ensure the similarity between the test model and the prototype internal pressure dynamic characteristic model, and puts forward an accurate test method to measure the internal pressure. It is also pointed out that the test error of internal pressure response may be caused by wind tunnel test. The effects of the area of the hole, the location of the hole, the internal volume of the building, the wind speed and turbulence of the incoming flow, and the internal disturbance on the internal pressure pulsation, the equivalent damping ratio and the resonance response are comprehensively analyzed. The applicability of several simplified methods for predicting the RMS ratio of internal and external pressure pulsation is compared. The physical meaning of the undetermined constant in the equation and its possible influencing factors are analyzed. Taking the actual project of a large span ultra-high monolayer factory building in a coastal area as an example, the wind tunnel test of the internal exterior pressure is carried out under four kinds of hole opening forms, and the distribution law of the wind load and the peak factor of the internal pressure is obtained. Compared with the suggested values of the standard body shape coefficient and peak factor, the stress situation of the end of longitudinal wall is mainly investigated, and the wind direction angle and the hole opening condition which are most unfavorable to the force on roof and wall surface are given, which provides a reference for the reasonable design of this kind of structure. The CFD numerical method is used to simulate the average wind pressure on the inner and outer surface of the longitudinal wall of a single open-hole powerhouse with the same ratio of length to span, and the results are compared with those of the wind tunnel test, and the effectiveness of the numerical wind tunnel is verified. The influence of plant length on wind pressure coefficient of longitudinal wall surface is discussed, and the range of end effect zone and the influence of plant length growth on it are also studied.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TU312.1

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