Abstract
Studies on dynamic impact of high-speed trains on long-span bridges are important for the design and evaluation of high-speed railway bridges. The use of the dynamic load factor (DLF) to account for the impact effect has been widely accepted in bridge engineering. Although the field monitoring studies are the most dependable way to study the actual DLF of the bridge, according to previous studies there are few field monitoring data on high-speed railway truss arch bridges. This paper presents an evaluation of DLF based on field monitoring and finite element simulation of Nanjing DaShengGuan Bridge, which is a high-speed railway truss arch bridge with the longest span throughout the world. The DLFs in different members of steel truss arch are measured using monitoring data and simulated using finite element model, respectively. The effects of lane position, number of train carriages, and speed of trains on DLF are further investigated. By using the accumulative probability function of the Generalized Extreme Value Distribution, the probability distribution model of DLF is proposed, based on which the standard value of DLF within 50-year return period is evaluated and compared with different bridge design codes.
Highlights
During the bridge design, static load effect should multiple dynamic load factor (DLF) for consideration of the dynamic effects
An evaluation of dynamic load factors for a high-speed railway truss arch bridge was carried out using the monitoring strain data and finite element simulation
On the basis of the results obtained from this particular study the following conclusions, which can provide reference for similar kinds of bridges, can be drawn: (1) For each plane of steel truss arch, the dynamic load factors (DLFs) decrease in turn in the bottom chord member, diagonal web member, deck chord member, and top chord member
Summary
Static load effect should multiple dynamic load factor (DLF) for consideration of the dynamic effects. Most studies using the analytical approach have been conducted to investigate the bridge-vehicle interaction and estimate the DLF. Ding et al [4] evaluated the dynamic vehicle axle loads on bridges with different surface conditions. Demeke et al [5] evaluated the dynamic loads on a skew box girder continuous bridge using field test and modal analysis. Deng and Cai [10] developed the dynamic impact factor for performance evaluation of existing multigirder concrete bridges using the Gumbel distribution. Even though the field tests had been carried out on many types of bridge structures, according to previous studies there are few field monitoring data on high-speed railway truss arch bridges. A long-term field monitoring was conducted on the Nanjing DaShengGuan Bridge to collect the dynamic responses induced by high-speed trains. To determine the appropriate DLF value for design purposes, a statistical analysis was conducted
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