Study On Statics Of Honeycomb Sandwich Bridge Deck Structure

Honeycomb sandwich structure is composed of honeycomb sandwich,top panel,and bottom panel.This kind of structure,which has specific stiffness,specific strength,and low quality characteristics,is widely used in many fields,such as aerospace,high-speed trains,ships,buildings,etc.And,when honeycomb sandwich structure is used in bridge engineering,honeycomb sandwich bridge deck occurs.Some scholars from Purdue University in the United States have done related research on steel honeycomb sandwich bridge deck,but this field is still blank in China.Aiming at the structure of honeycomb sandwich deck,the work done and the conclusions are as follows:(1)Firstly,the history of honeycomb sandwich structure and its application in various fields were reviewed,the basic theories and assumptions for calculating honeycomb sandwich structure were summarized,and the honeycomb sandwich bridge deck was determined to be mainly studied on the basis of HOFF hypothesis in this paper.(2)Based on sandwich theory and Y model,the mechanical parameters of honeycomb sandwich were deduced,which can provide data for establishing equivalent model of honeycomb sandwich by using ANSYS.We can know From the deduced x-and y-direction elastic modulus,that the honeycomb interlayer is isotropic in plane,and the equivalent sandwich can be regarded as an isotropic plate.(3)Based on Hoff theory,the expressions of deflection and bending stress of simply supported honeycomb sandwich deck with four sides were derived by using Timoshenko energy method.The energy method and the finite element model were used to calculate the deflection and stress of each part of sandwich plate.The finite element model includes the real model established by using honeycomb sandwich plate full size,and the equivalent model established by using sandwich plate theory.The results show that the expressions of deflection and bending stress derived by Timoshenko energy method are accurate.The equivalent mechanical parameters deduced using the Y model are correct.The equivalent model based on sandwich plate theory is more reliable and has little difference with the calculation results of real model.(4)On the basis of the expressions of deflection and bending stress derived from the energy method before,the critical buckling load of honeycomb sandwich bridge deck was deduced according to the principle of minimum potential energy.The eigenvalue buckling analysis and nonlinear buckling analysis of honeycomb sandwich plate were carried out by using ANSYS,and the influences of panel thickness,sandwich height,side length of honeycomb cell,and the wall thickness of honeycomb cell on the critical buckling load of the structure,were discussed.The rules were summarized and compared with the theoretical results.The results indicate that the thickness of the panel,and the altitude of the sandwich layer is greatly affected that the critical buckling load of honeycomb sandwich structure.This is the same as calculated by the expression of the critical buckling load that derive using the energy method;The wall thickness of honeycomb cell has little effect on the critical buckling load of sandwich structure,so ignoring the effect of cell wall thickness in deriving the expression will not cause much error,however,the shear strength of the interlayer will be reduced if the cell wall is too thin and eventually leads to transverse shear failure or global instability and too thick is not good either,resulting in an unnecessary waste of material that the cell wall thickness in the honeycomb sandwich deck structure should be between 3～5mm;According to the nonlinear buckling analysis,the side length of honeycomb cell has great influence on the critical buckling load of sandwich structure,and this is completely different from the calculation result of the formula,if ignoring the influence of cell side length on the buckling load of honeycomb sandwich structure that will inevitably lead to huge error.Therefore,before the energy method is used to calculate the buckling load of honeycomb sandwich structure,the side length of cell should be determined first,that the honeycomb sandwich deck structure studied in this paper is subjected to vehicle load Combined with the results of finite element analysis,the cell side length should not be less than 300mm to ensure that at least two cellular cells bear wheel load each time,and to avoid the instability of panels between the cores.(5)Taking a bridge in Canada as an example,the steel-polyurethane sandwich bridge deck used in the bridge is a sandwich structure,which is similar to the honeycomb sandwich deck studied in this paper and the stress conditions are similar as well,this example can be used for comparison.Honeycomb sandwich deck was used to replace steel-polyurethane sandwich deck,and other design parameters were unchanged.A finite element model was established and compared with literature under the same load condition to analyze the structural characteristics of honeycomb sandwich deck.The results indicate that the maximum stress of honeycomb sandwich plate used as the bridge deck is 215.12MPa bottom at the 0.95σ_y=333MPa that meets the requirements of the limit state of bearing capacity and the maximum deflection of 4.34mm is less than L/300=8mm that meets the requirements of the normal use limit state.The maximum deflection of honeycomb sandwich bridge decks under the same load condition is 22.5%lower than that of steel-polyurethane sandwich bridge decks.Under the same load condition,honeycomb sandwich bridge decks are compared with steel-polyurethane sandwich bridge decks:the maximum deflection low 22.5,the maximum tensile stress along the bridge is 13.5,the maximum compressive stress along the bridge is 26,the maximum tensile stress of transverse bridge is 19.9,the maximum compressive stress in transverse bridge is 7.9,the maximum equivalent stress is 7.5.This indicates that it is feasible to use honeycomb sandwich panels as the bridge decks.