Field-calibrated influence lines for improved axle weight identification with a bridge weigh-in-motion system

Bridge weigh-in-motion (BWIM) systems take influence line (IL) as a reference to calculate axle weights. The calibrated ILs based on field measurements can acquire better conformity with the actual situation and more actually represent the characteristic of existing bridges. Following the methodology proposed by O'Brien et al. (2006 O'BrienE.J., QuilliganM.J., & KaroumiR. (2006). Calculating an IL from direct measurements. Proceedings of the Institution of Civil Engineers, Bridge Engineering, 159, 31–34. [Google Scholar]), this paper presents back-calculating of the ILs from direct measurements taken on field tests for identification of axle weights of heavy vehicles. The algorithm for calibrating ILs is based on continuously measured bridge responses (strains) produced by two calibration vehicles passing across the instrumented bridge. In terms of the calibrated ILs, Moses' algorithm was applied to identify axle weights of moving vehicles by the least-square method. Field tests on highway US-78 in Alabama were conducted as a case study to evaluate the accuracy of the presented algorithms in calibrating ILs and to identify the axle weights by comparing with the static measurements, and with the measurements by the bending-plate weigh-in-motion (WIM) system on a one-to-one basis to demonstrate the accuracy of BWIM system relative to conventional pavement WIM systems. Finally, factors influencing axle weight identification, including the selection of ILs, the shapes of ILs and the scan numbers for collecting strain signals, were discussed.     

Nothing-on-road bridge weigh-in-motion considering the transverse position of the vehicle

Bridge weigh-in-motion (BWIM) is a technology that uses the bridge as a weighing platform to estimate vehicle weights. Previous research has shown that ignoring the transverse position (TP) of vehicles may lead to significant identification errors of vehicle weight for BWIM systems. However, the traditional method to identify the vehicle’s exact TP requires using axle detectors on the road surface. Aiming at achieving the nothing-on-road (NOR) BWIM, this paper proposes a novel NOR BWIM algorithm that is able to identify the vehicle’s TP and axle weights using only the weighing sensors. Numerical simulations are conducted using three-dimensional vehicle and bridge models and the proposed algorithm was used to identify the vehicle’s TP and axle weights. The results show that the proposed algorithm can successfully identify the vehicle’s TP and that the identification accuracy of axle weights and gross vehicle weight is significantly improved after considering the vehicle’s TP. The effects of the road surface condition, the vehicle speed, the vehicle width, and different measurement stations on the identification accuracy are investigated. The proposed algorithm is then verified by a field study and the results indicate that the proposed algorithm can achieve acceptable identification accuracy in practice.     

桥墩形式对连续刚构桥刚度的影响

在连续刚构桥中,中间桥墩采用墩梁固结体系,桥墩刚度的大小对全桥刚度和结构的使用功能影响比较大.而桥墩的形式对桥墩刚度有决定性作用,所以桥墩形式的选择是进行连续刚构桥设计优化的重点.本文结合西平线莫谷河2号连续T型刚构桥的设计,来分析桥墩形式对连续T型刚构桥刚度设计的影响.     

京沪高速秦淮河特大桥连续梁施工质量控制

结合京沪高速秦淮河特大桥连续梁施工情况,对施工中各段施工方案控制、桥梁线形控制、预应力钢筋混凝土施工质量控制等作了论述,以期确保连续梁施工质量,使其满足规范要求。     

某预应力混凝土连续梁桥内力计算分析

采用桥梁专用有限元软件MIDAS/Civil对某大跨度预应力混凝土连续梁桥的上部结构建立桥梁实体模型,并对其进行了内力计算分析,得出了不同荷载效应作用下桥梁的内力数据,同时对不同荷载效应按照正常使用极限状态和承载能力极限状态进行内力组合,绘出内力包络图,从而为大跨度预应力连续梁桥的配筋设计提供了理论依据。     

悬臂拼装多跨连续梁桥计算参数的选取研究

以孙口黄河公路大桥为研究对象,通过对主桥上部构造进行分析,对多跨连续梁桥的混凝土收缩徐变、非线性温度变化等计算参数的选取进行了研究,以确保连续梁桥设计满足规范要求。     

瓯江主桥五跨连续梁合龙段施工

介绍了瓯江主桥五跨连续梁合龙段施工顺序及其关键技术,阐述了如何保证合龙段施工质量、确保连续梁施工线型,并且对合龙段施工压重和不压重进行了详细的计算分析,以期指导今后同类型桥梁施工。     

预应力组合连续梁桥的设计问题探讨

在总结现有关于预应力组合连续梁结构理论成果的基础上,重点分析预应力效应,探讨在连续梁桥设计方面预应力组合结构的应用。     

桁架牛腿在连续刚构桥0号块施工中的运用

结合工程实例,介绍了桁架牛腿在连续刚构桥0号块施工中的运用,并对其强度、刚度、牛腿的抗剪抗弯能力、桁架变形、预埋件承载力等方面进行了力学计算,可供类似工程施工参考。     

基于挠度理论的连续梁与悬索组合桥梁结构静力计算

连续梁与悬索组合桥梁结构是一种新型组合结构体系,其结构受力本质尚不明确,为研究其静力特性,提出了一种基于挠度理论的解析计算方法。首先,假设恒载状态下主缆5段线形,确定恒载作用下主缆的线形公式和主缆内力;其次,将活载作用下结构简化为外伸梁和悬吊钢箱梁部分,考虑之间约束力和弯矩的传递,分别建立其挠度方程,以主缆变形为相容方程,迭代求解结构的内力和变形;最后,以一连续梁与悬索组合桥梁结构的方案设计为例,分别采用所提挠度理论方法、弹性理论方法进行静力计算,并和有限元结果进行对比分析。结果表明:弹性理论计算结果相比有限元结果误差较大,所提挠度理论方法得到的结构主要构件内力和变形值与有限元的计算结果差异很小。所建立的连续梁与悬索组合桥梁结构静力解析计算方法模型简单、计算精度较高,可为此类组合桥梁结构初步计算和设计提供参考。     

连续刚构桥悬臂状态稳定性分析

指出连续刚构桥因其跨越能力强得到广泛应用,但其悬臂状态的稳定问题较突出,针对某三跨连续刚构桥施工阶段最大悬臂状态进行稳定性分析,得出相关结论以期指导同类结构工程施工。     

浅谈连续刚构桥合龙段施工技术

结合具体工程实例,详细介绍了连续刚构桥合龙段施工技术,进行了合龙段变形分析,总结了该刚构桥合龙段施工经验,以使特大桥合龙后结构受力良好,保证施工成功。     

某连续梁桥静载试验研究

介绍了某等截面连续梁桥静载试验的目的和原则,并对加载方案设计、测点布置等进行了分析说明,通过对试验结果的分析研究得出该桥跨结构的实际承载能力、结构刚度满足设计要求等结论,为大桥的运营和养护提供基础数据。     

连续刚构梁桥主要病害原因分析

通过对现有连续刚构梁桥的病害进行分析,从材料、设计及施工等方面入手,探讨了桥梁病害的成因,以解决处理好连续刚构梁桥的病害,进而使连续刚构梁桥的耐久性进一步提高。     

大跨连续刚构跨中下挠问题研究

在归纳总结前人经验的基础上,从预应力钢筋混凝土材料本身的性质、力学性能及大跨连续刚构的设计理论、施工方法等方面做了较为详细的分析,并提出了相应的预防措施和解决方案,以延长桥梁的使用寿命,提高行车舒适性。     

预应力连续梁桥预应力张拉施工的要点简述

以十永线立交桥为例,论述了预应力连续梁桥预应力张拉施工控制的全过程,指出了施工中的注意事项,通过一些施工控制措施的实施,从而使预应力连续梁桥张拉施工顺利进行。     

连续梁桥整体顶升方案及应力应变测试研究

以京沪高速公路淮安废黄河大桥为例,研究了连续梁桥支座更换工作中多孔桥梁整体顶升方案,并采用电阻应变法监测试顶过程中梁体的应力应变增加值,验证了整体施工方案的可行性。     

简支T梁桥面连续预应力研究

通过对简支T梁的受力分析,提出了在墩顶现浇段处桥面采用预应力的连接,并与其他处理方法进行比较;利用有限元软件分析了桥面在预应力作用下对结构的影响,以工程实际作为验证,具有一定的工程价值。     

基于地震作用下连续钢桁梁桥动力响应分析

研究了某铁路连续钢桁梁桥在7级近源地震作用下桥梁跨中节点的动力响应,经有限元模拟计算,验证了该桥具有良好的抗震性能,以保证该连续钢桁架桥结构安全.     

Application of the continuous wavelet transform on the free vibrations of a steel-concrete composite railway bridge

In this article, the Continuous Wavelet Transform (CWT) is used to study the amplitude dependency of the natural frequency and the equivalent viscous modal damping ratio of the first vertical bending mode of a ballasted, single span, concrete-steel composite railway bridge. It is shown that for the observed range of acceleration amplitudes, a linear relation exists between both the natural frequency and the equivalent viscous modal damping ratio and the amplitude of vibration. This result was obtained by an analysis based on the CWT of the free vibrations after the passage of a number of freight trains. The natural frequency was found to decrease with increasing amplitude of vibration and the corresponding damping ratio increased with increasing amplitude of vibration. This may, given that further research efforts have been made, have implications on the choice of damping ratios for theoretical studies aiming at upgrading existing bridges and in the design of new bridges for high speed trains. The analysis procedure is validated by means of an alternative analysis technique using the least squares method to fit a linear oscillator to consecutive, windowed parts of the studied signals. In this particular case, the two analysis procedures produce essentially the same result.