单层索网等效非线性单自由度体系的地震反应研究

Investigation on the seismic response of equivalent SDOF of planar cable net with geometrical nonlinearity

点式玻璃幕墙单层索网主要承受平面外荷载,而其平面外刚度依托于索预应力及其平面外变形的几何刚度,具有强几何非线性。针对其质量刚度均匀分布特性,为考虑几何非线性对其地震反应的影响,提出单层索网等效非线性单自由度体系(SDOF)的数学模型,指出可通过研究SDOF地震反应来研究平面单层索网的地震反应特性;建立单层索网的简化单质点体系的物理模型,研究影响其地震反应的关键因素,即刚度、几何非线性特性和动力特性;研究几何非线性单质点体系的地震反应特性,分析研究表明:具有三次刚度的几何非线性单自由度体系,在一定地震作用和阻尼下的反应谱可由线性周期和非线性因子双参数控制,为单层索网幕墙的抗震设计提供基础性理论参考。

Serving as the supporting system for point-supported glass curtain wall, primarily to bear out-of-plane loads and actions, singlelayer cable net with strong geometric nonlinearity obtains its out-of-plane stiffness from pre-tension and deformation. In view of its even distribution of stiffness and mass, a mathematical model for equivalent SDOF of cable net is proposed. It is also indicated that the seismic response of equivalent SDOF can be applied to investigate the seismic response of cable net. Furthermore, based on a simplified single particle system for cable net, it is focused on the key factors for seismic response of cable net, including stiffness, geometric nonlinearity and dynamic properties. Finally, the seismic response of single particle system with geometric nonlinearity is investigated.It is shown that the seismic response spectrum for systems with geometric nonlinearity could be controlled by linear period and two nonlinear geometrical parameters, which could serve as fundamental theoretical reference for seismic design for cable net.