【摘要】 模态参数和索力是评估斜拉桥健康状态的关键参数。建立了崖门大桥的有限元模型并对其进行了基于环境激励的模态测试和拉索振动测试;提出了基于ERA的多参考点稳定图算法,设置不同的参考点,利用自然激励技术结合特征系统实现算法(NExT-ERA)识别模态参数,通过阻尼比、基于输出矩阵的一致模态指标(CMI_O)和模态置信度(MAC)作为判别标准,识别出崖门大桥的竖向和横向模态参数,通过和增强频域分解法(EFDD)识别结果的比较,可知该算法具有良好的识别效果;分析了斜拉索与主梁的共振频率范围,通过二次拟合识别较长拉索的低阶频率,根据两种不同方法的索力识别结果可知,该桥的索力分布比较均匀对称。更多还原

【Abstract】 For health monitoring of long span cable-stayed bridge,modal parameters and cable tension are the key parameters to assess the condition of the bridge.A finite element model of Yamen bridge was built.Modal test and cable vibration test of the bridge were performed under ambient excitation.An improved multiple reference DOFs stabilization diagram algorithm based on ERA(Eignsystem Realization Algorithm) was presented.By setting different reference DOFs in each group of data,NExT(Natural Excitation Technique)-ERA was used to identify modal parameters.Damping ratio,consistent mode indicator from observability(CMI-O) and modal assurance criterion(MAC) were used as thresholds to identify the most accurate modal parameters.Lower order frequencies were estimated by quadratic fit method,and the cable tension was estimated by two different methods.Based on the analysis of deck and cable vibration,it is evident that the vertical vibration of the bridge deck is tightly coupled with the cable vibrations within the frequency range of 0～3Hz.更多还原