非平稳地震激励下隔震曲线梁桥振动控制研究

曲线梁桥由于其平面不规则性导致结构在地震激励下产生弯扭耦合效应,使得隔震曲线梁桥的地震响应更加复杂。目前常用的控制方法是将隔震技术与附加减震装置相结合对曲线梁桥进行控制。本文将地震动考虑为一均匀调制非平稳随机过程,针对隔震曲线梁桥长周期、低频率的特点,选取Clough-Pension平稳地震动功率谱模型作为随机地震动输入模型,对无控(NON-C)、经典线性最优控制(COC)以及序列最优控制算法(SOC)三种状态下的曲线桥梁进行随机响应分析。通过建立曲线梁桥在随机地震动作用下的运动方程,求出减震控制结构的位移谱密度、加速度谱密度响应及时变方差。分析结果表明:序列最优控制算法(SOC)在使隔震层位移得到减小的同时,可以更有效地控制上部结构的地震响应,具有更好的控制效果。

Vibration Control of Isolated Curved Girder Bridges under Nonstationary Seismic Excitation

With the continuous development of structural seismic isolation technology, the use of seismic-isolation-device bridge designs is growing. The combination of isolation and additional damping devices is a commonly used method for controlling curved-beam bridges. Analyses of vibration control for research in the evaluation of seismic dynamic response have primarily focused on deterministic excitation, but deterministic earthquake excitation is not representative. In this study, we consider ground motion to be a uniformly modulated nonstationary random process and investigate long periods of low-frequency characteristics. Moreover, we select the Clough-Pension steady vibration power spectral model as a random vibration input for isolated curved bridges. To address the limitations of the classical optimal control algorithm, we derive vibration control equations using a sequential optimal control (SOC) algorithm. We then analyze the random responses of a curved bridge under three conditions: noncontrol, classical linear optimal control, and SOC algorithm. By establishing a curved beam bridge vibration equation of motion for random actions, we determine the displacement vibration control structure of the spectral density, acceleration spectral density response, and time variance. Analysis results show that the SOC algorithm can reduce the displacement of the isolation layer and more effectively control the seismic response of the upper structure, thus yielding a better control effect. The SOC algorithm has higher control performance and achieves better damping control.