基于长期监测的大跨度悬索桥主梁活载挠度分析与预警

为保证大跨度悬索桥运营期的健康与安全,提出了一种主梁活载挠度提取和预警方法。通过分段线性趋势项剔除和整体4阶傅里叶级数拟合的方法提取主梁活载挠度,对主梁活载挠度进行概率统计特性分析,提出了挠度异常和挠度超标的分级预警策略。结果表明：短时间内温度挠度基本呈线性变化,通过剔除短时间内主梁竖向挠度线性趋势项,可以有效提取活载挠度。主梁日最大活载挠度的概率统计特性与正态分布吻合较好,可将异常概率为99.7%的活载挠度作为挠度异常判定值。根据活载挠度概率分布模型确定系数对挠度异常判定值进行修正,可以降低由于概率分布模型拟合误差引起的误报警。可见本文提出的方法可以有效提取主梁活载挠度。挠度异常和挠度超标两级预警阈值,分别从概率统计和结构安全两方面对主梁活载挠度进行预警,可以有效评估主梁健康状态。

Analysis and early warning on monitoring girder vehicle-induced deflection of long-span suspension bridge

In order to ensure the health and safety of long-span suspension bridge in operation period, a method of vehicle-induced deflection extraction and early warning of main girder was proposed. Firstly, vehicle-induced deflection was separated by piecewise linear trend term elimination and fourth order Fourier series fitting. Then, the early warning strategy of deflection abnormity and deflection exceedance was proposed by the analysis of the probability and statistical characteristics. The results show that temperature deflections change linearly in a short period of time. Vehicle-induced deflections can be effectively extracted by eliminating the linear trend in a short time. Maximum daily vehicle-induced deflections is in good agreement with the normal distribution, and the abnormal probability of 99.7% can be used as the judgment value of deflection abnormality. The false alarm caused by the fitting error of the probability distribution model can be reduced by modifying according to the coefficient determined. It is concluded that the method proposed can effectively extract vehicle-induced deflections. Deflection abnormity and deflection exceedance can effectively evaluate the health status of the main girder from probability statistics and structural safety.