门式框架结构出平面外参数共振试验研究
Experimental Study on Out-of-Plane Parametric Resonance of Portal Frame Structure

本文对一个门式框架结构出平面外参数共振(动力失稳)问题进行了试验研究，采用振动台激发了门式框架结构的出平面外参数共振，观测和分析了门式框架结构出平面外参数共振的现象和机理，测量并探究了结构参数共振的稳定边界，研究了参数共振下激励频率与稳态响应幅值的变化关系。结果表明，当外部周期激励的频率大约是结构出平面外自振频率的两倍时，门式框架结构发生出平面外参数共振；在不稳定区域内，当固定激励幅值时，非线性稳态响应的幅值随激励频率的增大近似地呈线性减小。
This paper reports an experimental study on the out-of-plane parametric resonance (dynamic instability) of a portal frame structure. A vibration table is used to induce the out-of-plane parametric resonance of the portal frame, and the phenomenon and mechanism of this resonance are observed and analyzed. The stable boundary of the structural parametric resonance is measured and investigated. The relationship between the excitation frequency and the steady-state response amplitude under parametric resonance is investigated. The results show that out-of-plane parametric resonance occurs in the portal frame structure when the frequency of the external periodic excitation is approximately twice the natural frequency of the structure’s out-of-plane vibration. Within the unstable region, when the excitation amplitude is fixed, the amplitude of the nonlinear steady- state response decreases approximately linearly with the increase of the excitation frequency.