Study On Local Vibration Of Steel Bridge Deck Considering The Initial Geometric Imperfections And Residual Stress

The Orthotropic steel bridge deck has many advantages such as light deadweight,high bearing capacity and short manufacturing and installation cycle.It has been widely used in long-span bridge structures.Some Steel bridge deck stiffened plates often have local damage due to its vibration.To this end,this article has carried out some research on this phenomenon of vibration damage.It has certain theoretical and practical engineering significance.The main research work includes:(1)Combined with the domestic and foreign specifications on the initial geometric defects of stiffeners and the actual application of China's steel bridge deck stiffeners,a distribution model of initial geometric defects suitable for conventional steel bridge deck stiffeners has been proposed and apply it to the structural analysis of its stiffened plate.(2)The welding process and welding residual stress of the steel bridge deck stiffened plate were analyzed by numerical simulation.The simplified calculation formula of welding residual stress in the form of piecewise polynomial is given.The welding residual stress is applied step by step to each sub-unit of the steel deck stiffened plate.Based on this,the initial state of welding residual stress of the steel bridge deck stiffened plate was simulated.(3)Several representative trapezoidal rib stiffened plate test models were produced.The blind residual method was used to test the welding residual stress.The influence of the material and size of the stiffener on the welding residual stress was analyzed.The welding residual stress test value and the finite element calculation value were compared and analyzed.The distribution of welding residual stress of stiffened plate is given.(4)Based on the finite element(FEM)calculation software ABAQUS,modify the INP file in the program,and import the preset initial stress to the stiffened plate.The first-order buckling modal imperfection pre-calculated in the program in the form of command flow.Furthermore,the local vibration characteristics of stiffened plates considering initial geometric defects and initial stress are studied.(5)The steel deck stiffened plate commonly used in engineering;the initial geometric imperfection adopts the buckling mode of the stiffened plate.The welding residual stress was determined by a combination of numerical simulation and residual stress experiment.Using the energy principle,the structural vibration equation considering the initial geometric imperfection and welding residual stress is established.Through parameter were analyzed,the free vibration characteristics of the stiffened plate under typical boundary conditions are discussed,and study on the influence of initial geometric imperfection and welding residual stress on the dynamic characteristics of stiffened plates.(6)In order to verify the validity of the theory of local vibration analysis considering geometrical defects and residual stresses affecting steel bridge panels.Based on computationally powerful finite element software,we modified the command flow file in the program to import the preset initial stress values for the stiffened plate and the pre-calculated first-order buckling modal defects in the program.The local vibration characteristics were further studied and the theory was verified by numerical tests.(7)The vibration model considering the initial geometric imperfection and the initial stress stiffened plate was produced.The stiffened plate is freely vibrated by knocking,and the vibration characteristics of the trapezoidal rib stiffening plate are studied using a dynamic signal experiment and analysis system.At the same time,it also verifies the correctness of the theoretical analysis conclusion and using an exciter causes the trapezoidal rib stiffening plate to generate forced vibration.By analyzing the experiment data,the vibration characteristics of the trapezoidal rib stiffening plate under external excitation are studied.The vibration time-history curve and amplitude-frequency curve of the stiffening plate are given.