Study On Local Stability Of Orthotropic Steel Bridge Decks

The design of Orthotropic steel bridge panel is controlled by stability,however,there are some research on the stability of the steel bridge deck or limited to elastic stability,or failed to fully consider many influencing factors,and failed to coincide with engineering practice.Combined with the present steel reinforced development trend and mixed design concept is put forward,fully consider factors,and study the second kind of stability of equal-strength design and hybrid design of orthotropic steel bridge panel,and based on stable,starting from the structure of stiffening plate to solve mediastinal diseases plate at the top of the deck surfacing layer for durability and safety of t he structure of the bridge is of great significance.Based on the consideration of various influencing factors,the second type of stability of orthotropic steel bridge panel is studied in this paper,and the following works are mainly completed:Firstly,the stability theory of orthotropic steel bridge plate is introduced,including the stability theory of four-side simply supported thin plate,the elastic stability theory of stiffening plate and the elastic-plastic stability theory of stiffening plate.Based on the stability theory of simply supported plate with four sides,the width/thickness ratio limit of simply supported plate with four sides under pressure is deduced based on the stability theory of simply supported plate with four sides under pressure.The elastic stability theory of stiffening plate is introduced,and the elastic buckling coefficient of stiffening plate and the critical stiffness ratio of stiffening plate are deduced.The elastoplastic stability theory of stiffening plate considering plasticity is introduced,and the difference between the theory of pressure bar and the theory of orthotropic plate is that the transverse thin film is considered.Secondly,based on the finite element method,the basic building blocks of orthotropic steel bridge panel-plate elements,and simplified as four edges simply supported plate modeling analysis,and respectively introduces the compression of the factors affecting the ultimate bearing capacity of such as initial geometric imperfection,geometric nonlinearity,material nonlinearity,the influence of welding residual stress mechanism and included in the method in the finite element simulation,this paper discusses the initial geometric imperfection sensitivity and welding residual stress sensitivity a nd the width/thickness ratio of four edges simply supported plate after included in the different influence factors,in view of the engineering of common web of stiffener spacing and by this simplify the four edges simply supported plate,buckling stabilit y reduction factor is discussed,along with the change of the width/thickness ratio.The effect of different steel types on ultimate bearing capacity under the same ratio of width to thickness was studied,and the results showed that the efficiency of the improved steel decreased with the increase of steel strength,but with the same ratio of ultimate bearing capacity,the increase of steel strength could increase the design ratio of width to thickness.Then,based on the orthotropic steel bridge panel mode l with equal strength design and hybrid design,the pure compression ultimate bearing capacity and compression-flexure ultimate bearing capacity are studied,which include the initial geometric defects,welding residual stress,geometric and material nonlinearity.The results show that,under pure compression,the efficiency of the bearing capacity of the open stiffening bridge is about 50% when the strength of the mother plate is only increased,while the efficiency of the open stiffening bridge is about 20% when the strength of the stiffening rib is only increased,and the efficiency of the closed stiffening bridge is slightly higher than that of the open stiffening bridge.Under compression-flexuring load,the efficiency is close to that of pure compression.Finally,this paper expounds several common diseases of pavement layer paved on the steel bridge deck,in view of pavement cracking disease above the longitudinal clapboard to explain its failure mechanism,and from the perspective of the stiffening plate structure,under the width/thickness ratio limiting value of four edges simply supported plate theory,by increasing U rib height which near the longitudinal clapboard,to locally strengthen plate stiffness nearing the longitudinal clapboard,and compared with the original bridge panel,the results show that under the standard vehicle load,the Von Mises stress,SX stress,deflection at various points on bridge panel above the longitudinal clapboard down significantly,compared with the original effect is remarkable.The scheme only aims at strengthening the local stiffeners near the longitudinal clapboard and the economy is similar to the original bridge panel structure.