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针对运营车辆荷载作用下大跨PC梁桥动挠度特性问题,以琶洲大桥和洛溪大桥为背景工程,采用有限元计算和现场试验获取其车辆荷载动挠度,并分别在时域和频域,重点研究了运营车辆荷载作用下动挠度的统计特征和频谱特性。研究结果表明,模拟车辆荷载作用下的动挠度与实测动挠度吻合较好,两座背景桥的动挠度计算值以及实测值的均值和方差均在3～5mm范围内,均方差在2mm左右,变异系数超过50%,说明在大跨PC梁桥挠度监测时,不能忽略运营车辆荷载作用下桥梁结构挠度的动态效应,应采用动挠度来表征桥梁结构变形。功率谱密度曲线呈多峰分布,幅值谱属双峰分布,幅值谱主要频率集中在结构振动一阶频率及三阶频率附近。研究结果可为桥梁结构动态挠度监测方法研究和挠度成分分离研究,提供科学依据和基础数据。
Aiming at the dynamic deflection characteristics of long-span PC girder bridge under operating vehicle loads, taking the Pazhou Bridge and Luoxi Bridge as the background project, the dynamic deflection of the vehicle load is obtained by finite element analysis and field tests. Focusing on the statistical characteristics and spectrum characteristics of dynamic deflection under operating vehicle loads. The results show that the dynamic deflection of the simulated vehicle is in good agreement with the measured dynamic deflection. The computed values of the dynamic deflection and the mean and variance of the measured values of the two background bridges are in the range of 3 to 5 mm with a mean square error of about 2 mm. The coefficient of variation is more than 50%, which indicates that the dynamic effect of the deflection of bridge structure under operating vehicle load can not be ignored in the deflection monitoring of long-span PC beam bridge. Dynamic deflection should be used to characterize the deformation of bridge structure. The power spectral density curve has a multi-peak distribution, the amplitude spectrum is a bimodal distribution, and the main frequency spectrum of the amplitude spectrum concentrates in the first-order frequency of the structure vibration and the third-order frequency. The research results can provide a scientific basis and basic data for the research on dynamic deflection monitoring of bridge structures and the separation of deflection components.