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1、 摘 要 i大跨度屋盖结构风荷载及风致响应研究大跨度屋盖结构风荷载及风致响应研究 国家自然科学基金项目（50321003） 教育部“高等学校骨干教师资助计划”资助 博士生：周晅毅 指导教师：顾明 教授 二零零四年一月 摘 要 大跨度屋盖结构因具有质量轻、柔性大、阻尼小等特点，风荷载一般是结构设计的控制荷载。随着经济的发展、科技的进步，各种外形独特、结构形式新颖的大跨度屋盖结构大量涌现。 由于大跨度屋盖结构在风荷载和结构特性方面的复杂性， 至今还没有建立起有效的风振响应研究方法。本文从风荷载的测量和数值模拟、风压特性分析、抖振计算及静力等效风荷载等全方面入手， 为大跨度屋盖结构风致抖振响应研究提
2、供一个系统的方法。 本文主要进行了以下几个方面的工作： 1、获得屋盖表面非定常风荷载方法的研究。基于获取屋盖表面非定常风荷载和各测点间相干特性这一目的， 本文对刚性模型测压试验技术和多通道测压管路系统进行了研究。 首先基于电路传输线理论， 推导了可用于并联管道的耗散模型方程， 对理论分析模型进行了改进。 接着利用耗散模型方程对影响测压管路系统频响函数的参数进行了分析， 总结了一些定性的规律， 并对多通道测压管路系统中气动总管的气动平均性能进行了考察。 最后对测压管路系统进行了优化设计。 除了试验技术的改进外， 还提出了用神经网络方法预测未知点风压信息的数值方法。 2、大跨度屋盖表面风压特性的研
3、究。进行了三个不同大跨度屋盖结构的刚性模型测压试验， 对平均及脉动风压系数的等值线分布形式、 随风向角变化以及沿直线方向变化的规律、风压自功率谱及互功率谱进行了细致的分析， 得出了有关大跨度屋盖表面风压分布的一些具有共性的规律。 3、大跨度屋盖结构风致抖振响应计算的非定常方法及响应特性的研究。针对研究对象的线性或弱非线性特征， 提出了结构风致抖振响应的非定常频域计算方法， 并编制了动力计算程序 SWDP。 用此程序对一个实际大跨度屋盖结构进行抖振分析， 并就一些基本性问题进行了细致的讨论，主要包括： （1）准定常方法与非定常计算方法的比较。 （2）结构响应的频谱特征。 （3）主要频域计算参数（
4、包括参振模态数目、力谱及模态交叉项、阻尼比）对大跨度屋盖结构风致抖振响应的影响。 通过以上讨论， 对大跨屋盖结构的风致振动特性有了更进一步的认识。 4、大跨度屋盖结构静力等效风荷载计算方法的研究。根据大跨度屋盖结构风致振动的摘 要 ii特点背景和多个模态的共振响应一般均不能忽略、 同时应考虑模态之间的耦合影响， 提出了用于计算风振响应共振分量的修正 SRSS 法。在此基础上，用 LRC 法和考虑模态耦合系数的惯性风荷载法相组合来表示大跨度屋盖结构的静力等效风荷载， 并相应地给出了与中国规范协调的风振系数形式。 关键词：关键词：大跨度屋盖结构；多通道测压管路系统；神经网络方法；风荷载特性；非定常
5、计算方法；频域分析；静力等效风荷载；模态耦合影响 Abstract Since long-span roofs are generally light, flexible and low damping, they are prone to wind and the wind load is one of their most important loads to control the structural design. With the development of economy and progress of science and technology, more and more
6、 long-span roofs have been built, which have individual characteristics in architecture and structure. Due to the complexity of long-span roofs in wind loads and structural style, there is no effective method to research the wind-induced dynamic responses. In order to provide a systematic method to
7、research the wind-induced dynamic responses of long-span roofs, investigations on wind-tunnel testing technique and numerical simulation of wind loads, analysis of wind pressure characteristics, computation of buffeting responses, effective static wind load, are processed in this thesis. The researc
8、h is mainly focused on the following aspects: 1、Method of obtaining the non-steady wind pressures on long-span roof surface. For acquiring the non-steady wind pressures and coherent characteristics of measuring points on the surface of a rigid model, the pressure measuring technique of rigid model a
9、nd the parallel tube-manifold system are carefully studied. To accurately estimate the transfer function, theoretical representation of the dissipative model suitable for the parallel tube-manifold system is derived based on the transmission-line theory. Using the dissipative model, a parametric stu
10、dy over a large number of variables is processed, and some qualitative regularities are summarized. Then the pneumatic-averaged properties of manifold in the parallel tube-manifold system are discussed. At last, an optimal method for designing the tubing system with restrictors for measuring dynamic
11、 wind pressures is proposed. Neural network method is also used to predict the mean and fluctuating wind pressure coefficients and the power spectra of the fluctuating wind pressures using the limited data of wind pressures from the wind tunnel test. 2、Research on the wind pressure characteristics.
12、Based on the results of three long-span 摘 要 iiiroof structures from the wind tunnel tests, distributions of mean/fluctuating wind pressure coefficient contours, changing laws of mean/fluctuating wind pressure coefficients for different wind directions, power spectra of wind pressures, are analyzed.
13、Some valuable conclusions are achieved. 3、Non-steady computing method of wind-induced buffeting responses of long-span roof structures. According to the linear or weak linear property, a non-steady computing method is proposed and the dynamic computing programSWDP is developed. Using the program, th
14、e buffeting responses of a real long-span roof are computed, and some important aspects are discussed carefully, including (1) the comparison of quasi-steady method and non-steady method; (2) spectral properties of the structural responses; (3) effects of the main frequency-domain parameters (modal
15、numbers, cross terms of force spectra, cross terms of modals, damping ratio) on the responses. Through the discussions mentioned above, the wind-induced buffeting properties of long-span roof structures are further understood. 4、 The distribution of effective static wind load of long-span roof struc
16、tures. A modified SRSS method for computing the resonant responses, which takes into account modal coupling effects, is proposed. With the modified SRSS method, a formula for combinations of mean, background and resonant components, is given. In the formula, the background and resonant components are computed by the LRC method and the equivalent inertia force method considering modal coupling effects, respectively. Meanwhile, the
