| The rapid development of high-speed railway and urban rail transit bridges leads to the rapid popularization of steel structure bridges with convenient installation,light weight and high strength.However,the problems of structural vibration and noise of steel bridges caused by traffic loads have become more and more prominent.As the main structure of the steel bridge,the stiffened bridge deck makes a large contribution to the environmental noise when it vibrates.From the perspective of bending guided-wave,combined with vibration experiments and numerical simulations,the dynamic characteristics and vibration mechanism of steel-slab-ribbed bridge-deck are studied.The main research contents include:(1)The vibration test of the steel-slab-ribbed bridgedeck is conducted.(2)A test-verified three-dimensional dynamic model is established based on the modal superposition finite element method,plate vibration energy is then calculated.(3)Based on the finite element mode analysis method,the guided-wave types and dispersion characteristics are studied with a guided-wave model.(4)The effects of the four design parameters of plate thickness,rib thickness,rib spacing,and rib height on the vibration energy and characteristics of bending guided-wave,as well as the dynamic characteristics of the engineering size plate,are compared.The study found that:(1)The dominant frequency bands of plate and rib vibration responses tested under unilateral suspension constraints appear at 300 Hz and 400 Hz,and rib edge measuring point is greater.(2)The characteristic measurement point acceleration response of three-dimensional dynamic model is in good agreement with the test results.The calculated cut-off frequencies of the first to fourth-order bending waves of the guided-wave model are also in good agreement with the corresponding modal eigenfrequencies of the threedimensional dynamic model.The reliability of the two models is verified respectively.(3)From the perspective of energy,the energy change of the rib is basically the same as that of the plate,and the thinner plate under the boundary consolidation constraint has a higher vibration energy peak and a lower peak frequency.The influence of rib thickness and rib spacing on plate energy is mainly concentrated in the frequency band above 200 Hz and the local vibration frequency band above 400 Hz,respectively.The effect of rib height on the plate energy is relatively small and mainly concentrated in the 200-300 Hz frequency band;the energy peak point distribution of the engineering size structure is relatively scattered,mainly concentrated in 50 Hz to 500 Hz.(4)From the perspective of guided-wave,dispersion curves of bending waves appear pass-band and attenuation band interval.Guided-wave modes number decreases with the increase of plate and rib thickness.The upper and lower boundary frequencies of the attenuation band increase with the increase of the rib spacing,and decrease with the increase of the thickness and height of the rib.On the whole,the change of the rib size parameters has less effect on the vibration characteristics than that of the plate.Plate thickness has greatest influence on the out-of-plane vibration attenuation zone,the maximum bandwidth difference is 110 Hz.Therefore,out-of-plane wave vibration attenuation zone can be effectively controlled through plate thickness.The high frequency dispersion phenomenon of the engineering size plate is severe,and the guided wave mode intersection and ‘curve deflection phenomenon’ occur many times.The boundary frequency moves to lower band,and the bandwidth is 15 Hz. |
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