大跨度钢斜拉桥主梁监测挠度的评估与预警

Assessment and Early Warning on the Monitoring Girder Deflection of the Long-Span Steel Cable-Stayed Bridge

在南京长江三桥长期监测数据的基础上，提出了一种基于统计理论的钢斜拉桥主梁挠度的长期趋势评估和动态预警设置方法．首先，分析挠度随温度的变化特征，选取夜间0：00—1：00时段的挠度数据，剔除车辆荷载的影响，并考虑整体升降温作用，进而得到恒载挠度评估指标的基准值．其次，采用线性适度模型和基于实质的灰色关联度法对挠度进行评估，以2007～2010年的数据为例，结果表明：本文的评估结果与长期变化趋势一致，挠度变化趋势有助于指导桥梁结构病害的进一步检查．最后，基于一定保证率建立桥梁跨中挠度黄、红两级预警线，考虑交通量变化及累积损伤带来的影响，设置动态预警线．通过2008年雪灾前后状况和交通量增长情况两个示例进行检验，结果表明：本文设置的动态预警线不仅能有效地应用于桥梁正常运营或突发状况，还能根据桥梁的实际状况实现同步更新．

Based on long-term monitoring data in Nanjing No. 3 Yangtze River Bridge, a long-term trend assessment and dynamic early warning method on the girder deflection of the steel cable-stayed bridge with statistical theory was proposed. First of all, the variation characteristics of the deflection with temperature were analyzed. The data of 0 ： 00-1.00 at night was selected. The influence of vehicle load was removed, but the integral temperature effect was considered. The reference value of the deflection due to dead load was obtained. Secondly, the assessment was implemented by the linear moderate model and grey correlation analysis according to actual fact. Taking the data from 2007 to 2010 as an example, the results show that the established methods are consistent with long-term trend and helpful for the further inspec- tion of bridge defects. Finally, two-stage （yellow and red） early warning line was set up based on a certain guarantee rate. Considering the influence of traffic volume variance and cumulative damage, the dynamic warning line was established. Two samples of period before and after the snowstorm in 2008 and traffic volume growth were taken for verification. The results show that the proposed dynamic warning line not only can be effectively applied to the daily operation or emergency situation, but also achieve synchronous update according to the actual condition of the bridge.