| The corrugated web steel bottom plate composite box girder is a new type of bridge structure in which the concrete bottom plate of the traditional corrugated steel web composite box girder is replaced with a flat steel bottom plate.The force is more reasonable,the weight is lighter,and the span is larger.The steel base plate and corrugated steel web can be prefabricated and assembled in the factory to further speed up the construction progress.This bridge type has been put into use first in bridge construction in Gansu Province.Therefore,the research on this new structure of concrete roof-corrugated steel web-steel bottom plate is of great significance and value.In this paper,relying on the major science and technology project of Gansu Province in 2019,"Research and Industrialization of New Type Highway Steel-Concrete Composite Bridge Construction Technology",the bending mechanical properties,effective flange width and lateral load distribution of the structure are studied through experiments and finite element simulations.Get the following results:(1)Firstly,the model size and test points of the model test are designed and made in detail.Through the model test,the force of the top floor and the corrugated web under five control conditions and the deflection changes of the bottom of each web are obtained.Under eccentric load conditions,the farther the load acting position is from the main girder,the more uniform the stress distribution of the main girder will be.The stress distribution of the main girder near the direct load is very different.When subjected to concentrated loads,stress concentration will occur.The vertical marking value of the deflection influence line is related to the load acting position.The farther the web is from the load acting position,the smaller the vertical marking value at the web is,and the difference is smaller than the stress.(2)By introducing the shear corner of a new type of corrugated web steel-concrete composite box girder,the force of the corrugated steel web box girder is compared to the superposition of the bending moment produced by the bending action and the bending moment produced by the axial force.The deformation and top and bottom plate stress of the mixed composite box girder are theoretically deduced,and the boundary conditions of the test model beam are brought into the theoretical deduction formula to obtain an analytical solution.The specific parameters are brought into the theoretical derivation formula to obtain the stress value and deflection value of the concrete top and bottom plate in the span.The comparison shows that the stress value of the mid-span section is in good agreement with the theoretical calculation.(3)Take the experimental model beam as the background,refer to the current codes of various countries and compare with the finite element method.Under load,there is a big difference between national codes and finite element values.The main reason is that national codes consider different factors in calculating effective flange width.However,all national codes do not specify effective flange width under eccentric load conditions.Under eccentric load conditions,the effective flange width varies with the loading position.When the concentrated force moves outward from the symmetrical position of the cross section,it is found that the effective flange width coefficient is smaller when the load acts on the web position.On the whole,the effective flange width coefficient under the eccentric load is smaller than that under the symmetrical load condition.When the load is uniformly distributed in the middle of the span,the effective flange width coefficient has a maximum value of 0.924.(4)A spatial finite element model of a steel-concrete composite box girder bridge with corrugated webs is established,and the stress and deflection values of the model under different working conditions are calculated and compared with the experimental values.The inverse calculation of the load lateral distribution factor based on the stress effect and the deflection effect respectively and the comparison with the rigid-joined beam method showed that the inverse calculation of the load lateral distribution factor based on the deflection effect is more accurate than the inverse calculation of the load lateral distribution factor based on the stress effect.(5)Through Midas FEA software simulation,the transverse connection of different sizes and positions is set,and the influence of the size and position of the diaphragm and K-shaped brace on the transverse load distribution of the corrugated web steel bottom box girder is studied.It is found that with the increase of the width of the K-bracket between beams and the thickness of the transverse diaphragm in the box,the maximum load sharing ratio of the main beams gradually decreases,and the load sharing ratio of the center beam decreases more significantly than that of the side beams.This paper mainly studies the bending mechanical properties of corrugated steel webs and steel bottom plate composite box girder,which will provide certain basis and support for the design and popularization of this type of bridge in the future. |
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