基于静挠度线性时变建模的斜拉桥拉索损伤定量评估方法研究

The methods of evaluating the damage in stay cables are a hot research topic in the bridge engineering field at home and abroad. However, the existing quantitative evaluation methods of cable damage based on the modeling of static deflections do not fully consider the spatial distribution difference characteristics of temperature field and the short-period time-varying characteristics of wire breakage, leading to the defect in accurate and real-time evaluation. Hence, this project adopts a new idea of combining the multiple linear regression analysis with the dynamic time-varying analysis to carry out linear time-varying modeling analysis of static deflection, and two key scientific problems are solved through quantitative characterization, which are the influence laws of spatial distribution difference characteristics of temperature field and the short-time time-varying law of wire breakage. In detail, this project uses a variety of principal components from the temperature field to characterize the spatial distribution difference characteristics of temperature field, and uses time-varying parameters to characterize the short-period time-varying characteristics of wire breakage. The multivariate linear dynamic time-varying modeling method of static deflection and the solving method of time-varying parameters are studied, which contain the principal components of temperature field and time-varying parameters. Finally, a real-time quantitative evaluation method for cable damage is proposed by using the inherent correlation between time-varying parameters and the degree of cable damage. This method can simultaneously consider the spatial distribution difference characteristics of temperature field and the short-period time-varying characteristics of wire breakage, which can provide important reference in improving the accuracy and real-time capacity for the quantitative evaluation of cable damage.

斜拉索损伤评估方法是目前国内外桥梁工程界的研究热点，但现有基于静挠度建模的拉索损伤定量评估方法未充分考虑到温度场的空间分布差异特性和拉索断丝损伤的短时时变特性，导致在评估精度和实时性方面存在缺陷。为此，本项目采用将多元线性回归分析与动态时变分析相结合的新思路，对静挠度进行线性时变建模分析，重点定量表征温度场空间分布差异特性的影响规律和拉索断丝损伤的短时时变规律这两个关键科学问题。具体而言，本项目利用多种温度场主成分来表征温度场的空间分布差异特性，利用时变参数来表征拉索断丝损伤的短时时变特性，研究同时包含温度场主成分和时变参数的静挠度多元线性动态时变建模方法及模型时变参数求解方法，最终利用时变参数与拉索损伤程度之间的内在相关特性提出拉索损伤实时定量评估方法。此评估方法同时考虑了温度场的空间分布差异特性和拉索断丝损伤的短时时变特性，可在提高拉索损伤定量评估的精度和实时性方面提供重要参考。

在2018年，工程结构安全的长期智能监测与预警技术被中国科技协会列为公共安全领域三大前沿问题之一，其中斜拉索损伤问题更是关系到斜拉桥正常运营安全的关键问题。在利用静挠度异常变化定量评估拉索损伤时，有必要充分考虑斜拉桥温度场的影响规律和拉索断丝损伤的短时时变规律，从而为桥梁管养单位提供更精确、更及时的拉索损伤量化信息。本项目基于长期监测数据，深入研究了温度场、主梁挠度及斜拉索索力的的内在相关规律，提出了基于静挠度异常变化的斜拉桥拉索损伤实时定量评估方法。主要研究成果如下：.（1）斜拉桥温度场、主梁挠度及斜拉索索力的长短期监测与分析。基于某斜拉桥在役期间的实测数据，深入分析了温度场时空变化规律，发现温度场在时间和空间上是非均匀分布的，因此进行健康状况评估时，应充分考虑温度场的时空分布差异性；对于主梁挠度及斜拉索索力而言，其长期变化及短期变化特征都与温度场变化特征类似。.（2）温度场与温致效应相关性分析。对温度场与主梁挠度及斜拉索索力长短期监测数据进行相关性分析，建立了温度场与主梁挠度及斜拉索索力的非线性时变系数多元回归模型。采用卡尔曼滤波法求解非线性时变系数多元回归模型中的时变系数，并通过时变系数的时程变化情况对该桥的健康状况进行初步评估。.（3）斜拉桥拉索损伤情况实时定量评估方法。基于斜拉桥主梁静挠度及索力数学关系，提出斜拉索索力反演方法，并结合斜拉索自身力学特性，提出斜拉索损伤实时定量评估方法，最后通过有限元模拟及缩尺模型实验验证了所提方法的可行性。.研究成果已成功应用到之江大桥、锡澄运河大桥等桥梁群索损伤的精细定量动态评估中，验证结果表明评估误差在4.5%以内。该技术无需在所有斜拉索或吊索上布设传感器即可实现全桥群索损伤的精细定量评估，具备全面、精准、高效和便捷的技术优势，大幅减少了传感器数量并降低了工程成本，在工程应用过程中及时发现并更换了全桥范围内的严重损伤斜拉索，有利保证了桥梁运营安全。