Abstract
Dynamic properties of the bridge superstructure vary depending on many characteristics of the bridge and the loading conditions. In this paper, maximum Dynamic Amplification Factor was calculated for six different types of typical pre-stressed concrete beam bridges. It showed that each type of bridge with similar loading has a different range of Dynamic Amplification Factor. At the same time, every recently built bridge has different geometry and design load. Hence, it is difficult to determine a characteristic value of Dynamic Amplification Factor for the similar type of structures. By using fullscale dynamic and static bridge tests, it is possible to determine the necessary characteristics which show possibly high Dynamic Amplification Factor. This factor indicates if it is necessary to make a full-scale bridge dynamic analysis. It was found that those characteristics are natural frequency (first mode), damping ratio, relative deflection, and span and depth ratio. Obtained results from tests show a range of values for each of the characteristic. These ranges were analysed for reinforced concrete slab and pre-stressed concrete slab, and girder bridges.
Highlights
Safety assessment of the bridge requires information about the load effects and the structures capacity to resist these effects
Dynamic load results in an increase in the bridge deformations that are described by Dynamic Amplification Factor (DAF)
Additional dynamic load usually does not lead to major bridge failures, dynamic vehicle load can cause problems, which later contribute to fatigue, rapid deterioration of the surface wear and cracking of the concrete that leads to reinforcement corrosion (Cebon, 1999)
Summary
Safety assessment of the bridge requires information about the load effects and the structures capacity to resist these effects. Dynamic load results in an increase in the bridge deformations that are described by Dynamic Amplification Factor (DAF) It shows how many times the static load have to be increased to cover additional dynamic effects (Frýba, 1996). For pre-stressed reinforced concrete (PRC) slabs additional dynamic load may not the significant problem, but very high values of DAF can introduce cracks in the bridge deck (Rezaiguia, Ouelaa, Laefer, & Guenfoud, 2015). All over Latvia, many small bridges are designed and built by using typical element (for example beams) drawing albums, which are already about 50 years old. When these bridges were built, dynamic testing was performed only for non-typical bridges there are only few records of their dynamic performance. An evaluation method developed to evaluate dynamic performance of recently built non-standard RC and PRC bridges
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