Research On Section Optimization Of Steel Plate-Concrete Composite Girder Bridge

The steel plate-concrete composite beam structure not only can be quickly and standardizedly constructed,but also conforms to the national ecological and environmental protection concept,and has important significance for the development of the bridge industry in China。Based on the engineering example,this project selects the typical steel-concrete composite girder bridge structure.Through the design of the section parameters,the simulation is carried out by using the finite element software,and the simulation results are analyzed.The variation factors of the section design of the steel-concrete composite girder bridge are obtained.Regularity,and give specific cross-section parameter design value range,so as to provide reference for designers.This paper first summarizes two different analytical theories of steel-mixed composite beam structures.First,the analysis method that does not consider the relative slip effect between steel plate and concrete is mainly divided into elastic theory calculation method and plastic theory calculation method.When the elastic theory calculates the internal force of the composite beam,it is considered that both the steel and the concrete material are in the elastic deformation stage.It is concluded that:(1)The deflection of the steel plate beam is reduced to 1/27 when the height-to-span ratio of the beam is reduced to 1/27 when only the height-to-span ratio is kept constant,and the concrete slab is laid.At the stage,the increment of stress on the upper edge of the steel plate beam and the incremental change of the deflection change occur.It is recommended to consider the high-thickness ratio value of 1/26 in the design.(2)Steel plate beam under different construction stages,when the high span is relatively small,it will have a stress increment change.When the high-span ratio and the high-thickness ratio are considered at the same time,the stress increment of the steel plate beam changes smoothly when the beam height changes,and is much smaller than the former.It is recommended to consider the influence of the high-thickness ratio when designing the high-span ratio,and increase the thickness of the web while reducing the beam height.(3)As the high-span ratio is reduced to 1/27,the stress increase on the upper edge of the steel plate beam is much larger than its lower edge.Therefore,in design,if the high span ratio is reduced,it is recommended to increase the thickness of the upper edge of the steel beam.(4)In the range of width to thickness ratio of 11-13,the stability coefficient of steel plate beam is the closest,and when the aspect ratio is less than 11.,the stability coefficient of steel plate beam will increase,but the increase is low,Excessively increasing the thickness of the flange plate can result in economic waste.When the aspect ratio exceeds 13,the stability factor of the steel plate beam is reduced,and the decreasing extent increases as the thickness of the flange plate decreases.Therefore,when considering the overall stability in design,the width to thickness ratio can be taken as 11-13,which is subject to the relevant design data.(5)The upper flange stress of the steel plate beam at the mid-span position is differently distributed across the flange plate with different width-to-thickness ratio.When the aspect ratio is 8,the Von Mises Strain maximum distribution is close to the midline side of the bridge.When the aspect ratio is in the range of 11～13,the variation of the distribution area is consistent.When the aspect ratio is greater than 13,the Von Mises Strain maximum distribution area increment begins to increase significantly.This shows that when considering the pressure resistance of the flange plate from the maximum distribution area of Von Mises Strain,the width to thickness ratio can be 11～13.(6)When the aspect ratio is 11,the web thickness can be as good as 24mm-26mm.When the aspect ratio is 12,when the web thickness is increased from 26 mm to 28 mm,the extent of the decrease tends to be stable and remains at 0.5.In this range of values,its mechanical properties show a linear relationship.When the aspect ratio is 13,when the aspect ratio is 12.the maximum stress value changes regularly,that is,the web tends to be stable when the web thickness is between 26mm and 28mm.(7)In beam erection stage,the stress and deflection of steel plate girder and transverse connection are smaller than those of encrypted arrangement;in concrete slab laying stage,when encrypted arrangement is adopted,the stress and deflection of steel plate girder and transverse connection are smaller than those of equidistant arrangement,but the difference can be neglected.Considering the uniform stress of formwork,it can be taken into account in design.Consider the use of equidistant arrangement of transverse linkages.