Dynamic Behaviors Of U-Shaped Formed Steel Component With Stiffeners For Steel Bridge Structures Under Strike Loading

With current U-type thin-walled steel structures as the engineering background,finite element analysis software is used to analyze the dynamics behaviors of such thin-walled steel structures with low-speed impact load,including axial crashing behavior and transverse bending behavior.On this basis,the influence of longitudinal stiffening & strengthening solutions and transverse stiffening & strengthening solutions on the dynamic performance of U-type thin-walled steel structures are discussed.At last,existing numerical models and calculation result are compared and used to analyze the impact energy consumption performance of the U-type thin-walled steel structures influenced by the arranging approaches and hitting speed of stiffening ribs.The main conclusion of the study is as follows:(1)When the stiffening ribs are arranged,the deformation mode of the U-type thin-walled steel structures is affected by axial crashing.The invalid crashing end distortion is changed to overall buckling instability.The deformation of the structure bearing end is reduced significantly.The overall deformation of the structure is mainly web plate buckling deformation and partly flange bucking deformation.The stress of the mid span web of the U-type thin-walled steel structures with longitudinal stiffening ribs in the condition of axial crashing is higher than the U-type thin-walled structures with transverse stiffening ribs.When arranging stiffening and strengthening measures for stiffening ribs of the same mass,longitudinal stiffening and strengthening shall take priority.(2)Under impact bending load,the local distortion and bending of mid-span web are the major deformation type of U-shaped thin-walled steel without stiffing ribs,and the bending deformation of mid-span web and out-plane buckling of flange are the main deforming mode for thin-walled steel with stiffeners.It could be known that the initial stress peak of U-shaped thin-walled steel with stiffeners could be enhanced by three or four times compared with that of steel without stiffeners.Meanwhile,installing appropriThe main mode of bending deformation for U-type thin-walled steelstructures without stiffening ribs is wrinkle deformation partly and mid-span web bending.When stiffening ribs are arranged,the overall deformation of U-type thin-walled steel structures is mainly mid-span web bending.There is no obvious wrinkling deformation around mid-span crashing surface,while flange deformation is mainly outside concave deformation.Though comparison,it is known that the initial peak stress of the U-type thin-walled steel structures with stiffening and strengthening measures in the condition of bending load is 3-4 times higher than the ones without stiffening and strengthening measures.Meanwhile,stiffening ribs can increase the residual stress of mid span web plates and flange significantly,reduce the stress attenuation rate in the parts of web plates and flange,and improve the bend bearing capacity of the overall thin-walled steel structures.(3)The arrangement of stiffening ribs can enhance the performance of impact energy consumption upon crashing load of the U-type thin-walled steel structures.Adjusting the quantity and position of stiffening ribs can avoid or reduce the hazards of impact shedding and fracture instability of steel structures.The performance of impact energy consumption of U-type thin-walled steel structures is enhanced with the increase of crashing speed.In this study,when the crashing speed is increased from 10m/s to50m/s,the energy consumption efficiency is increased by about 40%.