Experimental Study on Dynamic Behaviors of Bridges for 300～350km·h~(-1) High Speed Railway

Based on the experimental research in recent years on the dynamic behaviors of bridges for highspeed railway in China,the test results of concrete bridges with common spans and bridges with special structure used for high speed railway with the design speed of 300～350km.h-1 were analyzed,which included natural frequency,stiffness parameters and the dynamic response of beam.The findings indicate as follows.The tested natural frequency and stiffness parameters of simply supported beams and continuous beams with common spans can meet the requirements of relevant codes,still there is particular allowance and can be further optimized.The measured values for the dynamic responses of both concrete bridges with common spans and bridges with special structure are relatively small,which can meet the operation requirements of EMU with the speed of 300～350km.h-1.The periodic irregularity effects of 32msimply supported box beams arranged with continuous equal spans are not obvious.Lateral resonance does not appear for simply supported beams with common spans;however,vertical superharmonic resonance has appeared at particular speed.While the vertical forced vibration frequency of EMU at particular speed is close to the vertical natural frequency of continuous beams with common spans and bridges with special structure,the vertical dynamic response of beam is amplified.