Study On Local Stability Of Stiffened Panel Of Steel-concrete Composite Bridge Tower

With the development of social economy and bridge construction technology,the design span of bridge has been continuously improved,which puts forward new requirements for the structural design and bearing capacity of bridge tower.Therefore,the traditional steel bridge tower and concrete bridge tower can no longer meet the requirements of structural design.On the other hand,the steel-concrete composite bridge tower has been rapidly developed and applied in recent years because of its superiority in mechanical characteristics.For the steelconcrete composite bridge tower,the stability of the stiffened steel siding of the outer steelconcrete composite bridge tower is the key to ensure the safe bearing capacity of the bridge tower structure.However,because it is usually a steel siding with large width-to-thickness ratio and multi-ribbed stiffening structure,and is constrained by the core concrete,its acceptance mechanism is different from that of the traditional steel bridge tower or concrete bridge tower.The current steel structure or other relevant design codes show the limitations of guiding design when dealing with the increasing size and complex structure of steelconcrete composite bridge towers.Therefore,in the local stability design of stiffened panel of steel-concrete composite bridge tower,the research results and specifications of traditional stiffened panel structure cannot be completely copied,and it is urgent to study the bearing mechanism of large-scale single-side limited multi-ribbed stiffened panel,so as to improve the design theory and guide the concrete calculation and design of stiffened panel of steel-concrete composite bridge tower.In view of the current design dilemma of stiffened panel of steel-concrete composite bridge tower,this study studies its bearing mechanism from the theoretical point of view,and studies the influence of design parameters on its stability by using finite element method,which has certain reference significance for the engineering design of stiffened panel structure of steelconcrete composite bridge tower.The specific contents of this study are as follows:(1)Stiffeners are orthotropic plates in structure,so the study of bearing mechanism can be carried out by following the related theories and research results of orthotropic plates.In this study,the mechanical characteristics of the stiffened panel of the steel-concrete composite bridge tower and the research results of the calculation method of conversion stiffness are systematically summarized.Finally,the physical model of the stiffened panel of the steelconcrete composite bridge tower is simplified as a single-side limited stiffened panel,and the formula for calculating the elastic buckling stress of the stiffened panel of the steel-concrete composite bridge tower is derived by using the principle of analogy orthotropic plate method,relying on the calculation formula of conversion stiffness obtained by the distribution method of bending stiffness of ribs and the distribution method of bending stiffness of ribs,and following Galerkin method.(2)The analytical solutions of elastic buckling stress obtained by different methods are compared and analyzed.It is found that the calculation formula obtained by rib bending stiffness distribution method is highly consistent with that obtained by traditional compression bar method,and its calculation accuracy is good under stiffening condition.Therefore,following this calculation formula,the steel consumption is introduced,and the design parameters are compared with the design specifications and existing design methods of bridge towers,and the limit value suggestion of width-thickness ratio of stiffened panels of steelconcrete composite bridge towers and the calculation formulas of the limit stiffness of their transverse and longitudinal stiffeners are obtained.(3)The finite element model experiment is carried out,and the method of establishing the finite element calculation model of stiffened panel of steel-concrete composite bridge tower is obtained by repeated comparative tests without sacrificing the calculation accuracy,and the accuracy of the finite element model is verified by comparison.(4)The design parameters of the stiffened panel of the steel-concrete composite bridge tower of the classic composite bridge tower are extracted,and the structural parameters of the working condition are analyzed according to the finite element parameters of the actual engineering design.The experimental study shows that the use of stiffening ribs can break through the limit of the width-thickness ratio of the steel-concrete composite panel,and the theoretical derivation results in this paper have high accuracy when used to calculate the elastic stress of the plate with the width-thickness ratio less than 120.(5)The variation of elastic buckling stress with finite element parameters such as widthto-thickness ratio,height-to-width ratio,spacing and height of stiffening ribs of steel-concrete composite bridge tower as stiffening short plate and stiffening long plate is studied,and the design points are summarized,which has reference significance for the design of stiffening wall plate of steel-concrete composite bridge tower.