【作者】 王彬；

【导师】 罗尧治；

【作者基本信息】 浙江大学 ， 结构工程， 2007， 硕士

【摘要】 随着工程技术的进步，现代大跨度空间结构，体系日益新颖，形式日益复杂，规模日益庞大。这对该类结构的分析计算工作提出了更高的要求。一方面，近来以来，大跨结构的静力计算、优化设计、位移跟踪等理论和方法已经比较成熟；另一方面，大跨结构的动力响应计算分析方法仍然比较薄弱，风振、地震响应的计算结果可靠性、准确性不易保证。然而，由于空间结构自重较轻，刚度不大，动力荷载可能在设计中占据控制地位，值得深入研究考察。基于VC++语言编制了大跨度结构风振系数计算和结构动力时程分析程序；在此基础上，对大跨度空间结构风振响应和地震响应的时频计算方法作了深入考察，对其中关键参数作了说明和建议；并且提出了可供工程设计参考的实用计算方法。首先，本文总结了脉动风荷载的表述方法以及随机振动的基本理论，详细分析风振响应计算的频域法，以及位移和内力风振系数的表达方法，提出一致风振系数的概念。通过引入应变能概念，解释了模态贡献，建议了合理截断数。通过大量的实例计算，考察各种参数在常用变化范围内变化对风振响应的影响，提出了双层柱面和球面网壳的风振系数取值公式。文中列举了一些工程结构的位移风振系数分布图。其次，本文详细研究了大跨度空间结构抗震计算之振型分解反应谱法。笔者认为现行规范对于参振模态的规定过于笼统，仿照高层结构计算中的相关概念，推导了大跨度结构的振型参与质量和振型参与系数的概念和计算方法，并利用之确定合理的参振模态。针对未知高阶模态可能贡献较大的情况，提出基于残量的虚拟模态法，可有效补充未被计算的高阶模态。最后，本文研究了大跨度空间结构动力响应时程分析方法，基于隐式积分(Newmark，Wilson-θ)格式编制了空间结构动力时程计算程序；阐述了适合大跨度空间结构计算的非线性隐式迭代格式；并结合工程算例比较了振型分解反应谱法和动力时程分析法的计算结果，认为地震振型分解反应谱法的计算结果不一定保证超过时程计算的最大值，因而对大跨空间结构进行时程分析是非常有必要的。更多还原

【Abstract】 Large-span spatial structures have been applied widely in many fields, with new forms and systems frequently developed by civil engineers. Till now, great acheivements have been made on static analysis of these structures, including branches such as mechanic solution, design optimization and displacement trace, etc. However, dynamic response solution is still a difficult problem, for the reliability and accuracy are not necessarily ensured. To light-weight, low-stiffness large-span sturctures, dynamic responses could be a dominant consideration in design process, thus, enough emphasis should be laid on dynamic problems such as wind or earthquake induced vibrations.In the paper, thorough review and research are put on solution of wind and earthquake induced responses for large-span spatial structures, in which some key parameters, e.g. superpostioned vibration mode number, are elaborated or specified. Furthermore, practical calculation methods for wind and earthquake induced vibration are also suggested. Related research is performed via programming on VC++ platform, and these programs are incorporated into MSTCAD structural design software.The paper summarizes methods to describe fluctuatitive wind pressure, and adopts random vibration theory in the calculation of wind-induced responses within frequency domain. Gust loading factors are defined in terms of displacements and internal forces, and "consistant loading factor" are proposed for a whole structure. Strain energy is calculated to reflect mode contribution to wind-induced vibration, on which basis, a proper number of mode-superposition order is suggested. After large-scale parametric analysis, practical formulae for gust loading factors of two typical large-span structures are proposed.The paper also put emphasis on mode superpostion response spectrum (MSRS) method for seismic response of large-span structures. "Modal attendance mass" and "modal participation factor" are defined and deduced, and further used for determination of proper mode-superposition order. A new "virtual vibration mode method" is proposed in case of unknown high order modeshape accounting for a large percentage in seismic response.Last but not least, the paper takes a serious review of time-history dynamic response calculation for large-span spatial structures. Implicit and explicit intergration scheme are studied and compared, while linear and nonlinear solution methods are both elaborated. A time-history dynamic solution program module is developed, using Newmark/Wilson-θ implicit intergration scheme. Based on that, calculations are performed to practical structures, and comparisons are made between time-history solution and MSRS results. The results show that MSRS results are not necessarily larger than that of time-history solution, hence, the latter method cannot be neglected in analysis and design of large-span structures.更多还原