点支式幕墙单层索网谐波地震响应的几何非线性研究

Nonlinearity in seismic response of a cable net in point-supporting glass wall

预应力平面单层索网是几何非线性较强的柔性张拉结构,由索中预拉力及几何非线性提供平面外刚度,在静力平衡位置预应力刚度较小,荷载作用下结构发生较大变形,因而产生了较大的几何刚度。针对几何非线性对此结构受力特性影响的重要性,对结构几何非线性作了定量分析,提出了几何非线性因子的概念;采用几何非线性时程分析方法,探讨了影响不同几何非线性的单层索网的谐波地震响应。分析结果表明,索网长宽比及索预应力对几何非线性影响较大;单层索网动力响应存在峰值共振偏移现象;并指出峰值共振频率不同于结构的线性自振频率和非线性自振频率。

A pre-stressed single-layer cable net falls into a group of flexible tensile structures with its strong geometric nonlinearity,which provides the cable net with the stiffness out of plane as a result of stress stiffing together with pre-stress.Due to the limited stiffness offered by the pre-stress of cable,the cable net will undergo large deflection under certain loads,which make it necessary to take the large deflection effects into account,it triggers the strong geometrical nonlinearity.Considering the importance of nonlinearity of the mechanical characteristics of the cable net,the nonlinearity of the cable net was quantified here with a factor of nonlinearity.With the help of transient analysis of the cable net of different geometric nonlinearity,the seismic response was investigated under harmonic activation.Finally,it was concluded that the shape of the cable net and the pre-stress affected its nonlinearity greatly;the peak resonant vibration would move aside for its nonlinearity and its corresponding frequencies were rather different from the linear frequencies and nonlinear frequencies provided by other scholars.