基于中性轴指标的混凝土梁桥长期监测与性能评估

Long-Term Monitoring and Performance Assessment for Concrete Beam Bridge Based on Neutral Axis Index

摘要:

提出基于中性轴的长期监测指标体系与性能评估方法。依托河北高速某分离式立交桥，建立基于监测指标的健康监测系统，并采集结构应变信息；采用多分辨率小波分析，从原始应变中分离由交通荷载引起的静态响应，根据设定的峰值显著程度拾取峰值-谷值对，拟合应变幅分布并导出实测中性轴参数序列；从累积数据中提取中性轴指标，比较分析不同评估周期的统计特性差异。结果表明，日周期下中性轴指标受环境干扰少，可表征结构在长期监测中的性能退化。

Abstract:

A long-term monitoring index system based on neutral axis（NA) position and the corresponding performance assessment method were proposed. Based on a detachable viaduct in Hebei expressway, a health monitoring system based on monitoring indicators was established, and the structural strain information was collected. Static response caused by traffic loads was separated from original strain signals by the multi-resolution wavelet analysis. The peak-valley pairs were picked in accordance with the designated peak prominence. Then the strain amplitude distribution was fitted and the measured NA arrays were derived. Finally, the neutral axis index was extracted from the accumulated data, and the statistical characteristics of different evaluation periods were compared and analyzed. The results show that the proposed neutral axis index in daily periods is less disturbed by the environment, which can represent the performance degradation of the structure in the long-term monitoring.