钢筋混凝土板模态频率的温度效应分析及剔除方法

考虑到温度荷载作用下钢筋混凝土梁桥的模态参数产生变异,进而导致基于动力指纹的桥梁损伤辨识方法精度降低甚至失效。以钢筋混凝土板为例,提出了一种考虑内部温度不均匀分布特性的模态频率温度效应剔除方法。首先,采用主成分分析算法,提取温度主成分,构造了预测模型输入参数;其次,通过遗传优化支持向量回归,建立了钢筋混凝土板模态频率预测模型;最后,结合钢筋混凝土板模态频率长期观测值,基于训练好的遗传优化支持向量回归模型,剔除温度对模态频率的影响。试验结果表明,该方法能够准确预测不同温度分布状态下的模态频率,并有效剔除温度引起的模态频率变化。

Analysis and Eliminating Method for Temperature Effect on Modal Frequency of Reinforced Concrete Slab

Temperature variation causes the significant change of modal frequencies of reinforced concrete bridges, which makes the vibration-based damage detection method fail to accurately identify structural damage. To eliminate the temperature effect on the modal frequencies, a novel approach is proposed based on Support Vector Regression optimized by Genetic Algorithm (SVR-GA) considering non-uniformly distributed temperatures inside the bridges. A reinforced concrete slab is monitored and used to demonstrate the proposed method. Firstly, temperature principal components are extracted by Principal Component Analysis (PCA), and used to construct the input parameter vectors of prediction models. Secondly, the prediction models for modal frequencies of reinforced concrete slab are constructed by use of SVR-GA. Finally, temperature effect is removed based on the long-term measurement and prediction of modal frequencies. Experimental results indicate that the proposed method can accurately predict modal frequencies under temperature non-uniform distribution, and effectively eliminate the change of modal frequencies caused by temperature variation.