基于振型贡献系数的空间结构振动反应研究  

Vibration response computation of spatial structures based on mode contribution factors

作　　者：廖冰[1] 罗永峰[1] 

机构地区：[1]同济大学建筑工程系,上海200092

出　　处：《空间结构》2014年第1期9-17,共9页Spatial Structures

基　　金：国家自然科学基金项目(51378379)

摘　　要：高阶振型对结构振动反应影响的大小与结构的类型直接相关,现有研究对象主要为高层建筑或大跨度桥梁,而针对大跨度空间结构高阶反应的研究,特别是基于振型贡献系数研究高阶反应相关参数的规律变化,目前还很少.本文以刚性大跨度单层扁网壳结构为研究对象,分析比较反应大小不同的振型贡献系数及其累积趋势变化.提出结构特征点刚度比参数ρ的概念,并同时采用结构矢跨比f和特征点刚度比ρ两个参数表征单层网壳的刚度特性,研究不同f和ρ对高阶振型贡献系数的影响;采用典型硬土场地地面运动的加速度设计谱表征地震激励,对比分析不同ρ和f对高阶振型加速度谱坐标的影响.基于振型贡献系数和加速度反应的变化规律比较结果,总结出单层扁网壳振型反应的分布特征和显著程度,提出了判断单层网壳结构振型反应绝对贡献大小以及高阶振型在弹性地震设计反应谱上的卓越周期区域的方法.本文关于高阶振型反应规律的研究成果,也适用于其他类型刚性空间结构的地震反应分析.The effects of higher vibration modes to structural dynamic responses are directly related to the structural types. Current researches on this subject are mainly focused on high rise buildings and large- span bridges. However, there are few achievements aiming at the higher mode responses of large-span spatial structures, especially on the correlations between mode contribution factors （MCF） and high mode response parameters. In this paper, a single-layer shallow latticed shell is taken as an example. The contribution factor of the different vibration mode and its accumulation trend for a typical rigid large-span structure are investigated. The stiffness ratio, p, a new parameter of characteristic structure point is defined. Using the stiffness ratio and the rise span ratio f of the structure to represent the stiffness characteristics of the latticed shell, the effects of the contribution factors of higher vibration modes under different p and f are also investigated. Employing the acceleration design spectrum of a typical hard soil site, the effects of p and f on the acceleration spectrum ordinates of higher modes are analyzed and compared. Based on the comparison of MCF and acceleration, the distribution characteristics and significance levels of mode responses of the latticed shell are concluded. A method for evaluating the absolute contribution of mode responses of the latticed shell and a method for evaluating the region of the predominant period of the higher modes in the seismic design spectrum are proposed. The achievements about the higher mode responses in the paper can also be useful for earthquake response analysis of other types of rigid spatial structures.

关 键 词：大跨度空间结构 高阶振型反应 振型贡献系数 加速度谱坐标 

分 类 号：TU311.3[建筑科学—结构工程]