Research On Vibration And Noise Reduction Of Stiffened Plates With Damping Layer In Steel Bridges Based On Bandgap Characteristics

As the problem of vibration and noise of steel box girder bridges becomes more and more prominent,its impact on pedestrians and the surrounding environment has attracted great attention from society.The method of reducing vibration and noise of steel box girder bridges has once become the focus and difficulty of the industry.In the field of physics,the periodic structure "phononic crystal" with elastic wave band gap characteristics is expected to introduce new ideas and methods to solve the vibration and noise problem of steel box girder bridges.However,the current understanding of the application of "phononic crystals" to bridge structures is very limited.In this context,this paper conducts an in-depth study on the acoustic and vibration characteristics of steel bridge stiffening plates based on the band gap characteristics of "phononic crystals".Firstly,the corresponding theoretical basis is given and the feasibility of applying periodic structure to bridge engineering is explained theoretically.then the correctness of the finite element method to solve the structural band gap is proved by the calculation examples in the existing literature.Subsequently,the band gap characteristic analysis was carried out for the stiffened plates with periodic structural characteristics in the steel box girder bridge,the existence and applicability of the band gap were verified by the vibration transmissibility,and the scale test of the U-rib stiffened plates was further verified.Furthermore,based on the common vibration and noise reduction measures of the steel box girder that is the method of laying constrained damping layer,the influence of this method on the structural band gap is discussed,and the structural band gap is combined with the laying of constrained damping layer to achieve the purpose of vibration reduction and noise reduction in the whole frequency domain in the range of 0 ～ 1000 Hz.Finally,the actual steel box girder bridge is used as the engineering application background to explore the practical engineering application value of the above methods.The main conclusions obtained are as follows:(1)Take the U-rib stiffened plates of the steel box girder as an example,there are three obvious band gaps in the range of 0 ～ 1000 Hz.The main reason for the band gap is the resonant coupling between the U ribs and the base plate,so that the stiffening plate lacks a corresponding bending wave vibration mode in a specific frequency range and appears to be “relatively stationary”.(2)As the thickness of the substrate increases,the band gap moves toward high frequencies and the width becomes narrower;the thickness of the U rib increases,and the band gap width becomes wider;the U rib spacing and the U rib opening width increase,which has a greater impact on the band gap and is more complicated.There are band gaps in the plate-rib stiffened plates and the large U-rib stiffened plates with UHPC layer in the range of 0 ～ 1000 Hz.The band gap of the plate-rib stiffened plates is the widest,followed by the U-rib stiffened plates,and the band gap width of the large U-rib stiffened plates is the narrowest.(3)Laying the constrained damping layer at different positions of the U-rib stiffened plates has little effect on the band gap frequency and band gap width;the increase of the damping layer damping causes the band gap to move to high frequencies and widen the band gap width.(4)When the constrained damping layer is laid on the U-rib and the surface of the substrate at the same time,it has the greatest impact on the transmission rate;the change of the damping layer damping has little effect on the transmission rate;the change of the thickness of the damping layer significantly reduces the vibration in the passband;the change of the thickness of the constraining layer causes vibration amplitude remains the same,and the vibration frequency moves to low frequency;the vibration attenuation effect is best when the steel confinement layer is used.(5)The method of laying constrained damping layers based on band gap characteristics can be used in actual bridge structures and achieve the purpose of vibration and noise reduction in the full frequency domain that meets actual engineering requirements.