单层平面索网结构风振响应的几何非线性特性研究

单层索网体系具有刚度小，质量轻，阻尼小等特点，对风荷载较为敏感，目前对该结构体系风振响应分析的相关研究很少，我国现行幕墙规范相关设计方法也不完善，深入研究索网结构的抗风性能显得尤为迫切。本文以线性自回归模型模拟脉动风速，采用随机模型时程分析方法计算索网的风振响应，探讨考虑不同脉动风速空间相干函数对分析结构风振响应的影响，着重研究在3种索网分析模式下的动力时程响应特征，以及在静力荷载作用下索网的非线性程度，分析结果表明：采用与风频率相关的空间相干函数进行索网的响应分析更合理；索网在平均风荷载作用下达到平衡位置后，在脉动风荷载作用下的非线性程度较弱，可以近似作为线性结构处理，因此可以平均风荷载作用下的平衡位置作为基准，采用频域方法分析单层平面索网的风振响应，这为下一步系统地研究点支式幕墙单层平面索网结构的抗风设计方法奠定基础。

STUDY ON NONLINEAR CHARACTERISICS OF WIND-INDUCED RESPONSE OF A MONOLAYER CABLE NET SYSTEM

A monolayer cable net system is sensitive to wind loads due to its characteristics of weak stiffness,light weight,and small structural damping.However,there are few studies on its wind-induced vibration performance,besides,the correlated design methods in current codes and specifications still await to be perfected.Therefore it is imperative to lucubrate wind-resistant behavior of cable net systems.An auto-regressive(AR) model is employed to simulate wind speed time series,and influence of various spatial coherence functions of fluctuating wind velocity on wind-excited responses of cable nets is analyzed.Three models are put forward to analyze dynamic responses of cable nets through numerical computation in time domain.And the nonlinear characteristic of cable nets under static loads is also studied.Conclusions can be drawn that it is more reasonable to consider spatial coherence functions related to wind frequency;vibration of a cable net subjected to fluctuating wind loads shows weak nonlinear properties after it reaches a new equilibrium position under mean wind loads;thus the wind-induced response of a monolayer cable net can be approximately regarded as the response of a linear structure with respect to its equilibrium position in frequency domain.All these pave the way for further systematic studies on wind-induced responses of monolayer cable nets with point-supported glass facades.