【作者】 陈贤川；

【导师】 董石麟；

【作者基本信息】 浙江大学 ， 结构工程， 2005， 博士

【摘要】 大跨度屋盖结构具有优美的造型和良好的性能,被广泛应用于各种大型公共建筑中,但是其风振理论却没有得到应有的发展。风振理论的缺乏将使大跨度屋盖结构的设计或偏于危险,或过分保守而导致不经济。本文在虚拟激励法和模态叠加法的基础上建立了一套完整的风振理论,并将其应用于大跨度屋盖结构的风振响应分析和静力等效风荷载的求解。本文工作主要包括以下几个方面: 1、脉动风精确、高效分析方法的研究。脉动风的频率成分较低,背景响应的比重较大,传统虚拟激励法和CQC法完全忽略了高阶模态对背景响应的贡献,当参振模态选取不合理时,两者会引起较大的误差,在理论上存在一定的缺陷。本文首次将虚拟激励法和模态加速度法结合起来,得到了理论上精确而高效的改进虚拟激励法,进而结合自适应积分方法,编制了脉动风随机响应分析程序,并全面分析了以下因素对大跨度屋盖结构风振响应分析结果的影响:(1)参振模态耦合项;(2)传统虚拟激励法和改进虚拟激励法;(3)不同风速(压)自谱;(4)脉动风相干函数及衰减系数的不同取值;(5)准定常和非定常脉动风;(6)响应谱函数的积分上限。上述分析表明了本文理论和程序的精确性和高效性,同时也有助于正确认识各种因素对风振响应分析结果的影响。 2、合理参振模态的研究。改进虚拟激励法理论上很精确,但与传统虚拟激励法相比,其计算效率相对较低。传统虚拟激励法通过合理选取参振模态,也可以得到较为准确的计算结果。基于上述理由,本文从能量概念出发,首次推导了模态贡献系数的计算公式,并定义了参振模态的累积模态贡献系数,其中模态贡献系数可用于识别和选取基本模态以及其它对风振响应具有较大贡献的模态,累积模态贡献系数可以定量判断参振模态的合理性。根据基本模态在模态序列中的阶次,可以将结构分为基本模态在高阶和在低阶两种类型,这两种结构受脉动风空间相关性的影响正好相反。在定量判断参振模态合理性的基础上,本文提出了两种提高参振模态合理性的新方法,这两种方法与基于平均风位移的模态补偿法一起,形成了一套具有较强可操作性的构造合理参振模态的完整体系,从而在保持传统虚拟激励法所具有的高效性同时,提高了其计算结果的精度。 3、脉动风静力等效风荷载计算方法的研究。本文从不同角度出发,提出了多种静力等效风荷载计算方法,可以适用于不同的场合。MGBJ法将规范的一阶模态惯性荷载法(GBJ)推广到多模态参振的情况,并改进了GBJ法在计算背景响应静力等效风荷载方面的缺陷。通过理论推导,本文首次建立了脉动风响应互谱矩更多还原

【Abstract】 With their beautiful shapes and excellent performance, long-span roofs have been widely applied for various large public buildings, but the theory of wind-induced vibration and equivalent static wind load of long-span roofs has not been well developed yet. The lack of such theory will make the roofs either in danger or wasteful. In order to provide a systematic method to research the wind-induced vibration and equivalent static wind load of such structures, the pseudo-excitation method and mode-superposition method are employed in this thesis. The research is mainly focused on the following aspects:1. Accurate and high efficient computing methods of wind-induced buffeting responses of long-span roof structures. Both the traditional pseudo-excitation method and CQC method ignore the contributions of high-order modes to the background component of the wind-induced response completely. Sometimes this will cause obvious errors. Based on the pseudo-excitation method and mode-acceleration method, a new computing method named modified pseudo-excitation method is proposed, which is theoretically accurate and high efficient. Then a dynamic computing program is developed based on the proposed method and self-adaptive quadrature method. Using the program, the following aspects are discussed carefully, including: (1) the cross terms of all computing modes; (2) the traditional pseudo-excitation method and the modified pseudo-excitation method; (3) different wind speed (pressure) spectra; (4) different coherent functions and decay factors; (5) the quasi-steady method and non-steady method; (6) the upper boundary of the quadrature. Through these discussions mentioned above, the accuracy and efficiency of the theory and program are validated, and the influence of these aspects to the result of the computation is properly understood.2. Research on constructing reasonable computing modes. Although the modified pseudo-excitation method is accurate on theory, it is relatively less efficient compared with the traditional pseudo-excitation method. The latter can also get a correct result through reasonably selecting a group of computing modes. Considering the reasons mentioned above, the mode-contribution-factor is proposed to identify and select the fundamental mode of the structure and all other modes contributable to the wind-induced response, and the cumulate mode contribution factor of the selected modes is defined to judge the reasonability of the computing modes. According to the order of the fundamental mode in the mode series, the structures can be classified as two different categories, and the opposite influence of the space coherence of the wind to the two structures can be found. Furthermore, two methods are proposed to improve the reasonability of the modes chosen for the mode-superposition method. Together with the mode-compensation method based on the displacement of the mean wind, the three更多还原