Analysis Of Deflection And Dynamic Characteristics Of Three-span Continuous Beam Corrugated Steel Webs With Variable Cross Section

Corrugated steel web box girder bridge as a new type of steel composite structure at home and abroad use more and more frequently.It has many advantages,such as low self-weight structure,high prestressing application efficiency,simple construction,across ability outstanding and beautiful appearance.From the beginning of 1980 s after this type of structure first appeared in France,it will soon be in Japan,Germany and other countries to be promoted,the corresponding research is also gradually.Although China started late,but with the depth of the study,there are a large number of the current type of box girder bridge,and gradually toward the direction of large span variable direction.With the increasing complexity of the structure,the research content is greatly increased.In this paper,a large span variable cross-section corrugated steel web continuous girder bridge is studied.The main contents of this paper are to study the calculation method of the deflection of the long-span variable cross-section continuous beam of corrugated steel web under the action of shear deformation and shear lag effect.The method of calculation is deduced by energy variational method,and a simplified calculation method for the moment of inertia of corrugated steel web is proposed.On this basis,the three-dimensional finite element model is established to validate the formula.The results show that the calculation method can accurately estimate the deflection of each position of the box girder under the condition of satisfying the engineering precision,which can play a guiding role in the construction design.In this paper,the dynamic characteristics of corrugated steel web box girder are studied,and the beam element and solid element model are established respectively,their characteristics are compared and analyzed.By comparing the solid model and the beam element model,we can know that under the premise of satisfying the engineering precision requirement,the model can be modeled by engineers who are familiar with the engineers without having to build complex solid models,and the beam element model can obtain accurate results.In addition,a common concrete web box girder with the same span is laid.The self weight of the two,the bending moment of the pier and the bending moment of the the mid span,the section characteristic,dynamic characteristics are compared and analyzed.The results show that the weight of the corrugated steel webs beam is reduced by about 20%,the maximum positive moment of the middle of span is reduced by 11.7%,and the maximum negative bending moment of the pier top is reduced by 20.7%,compared with that of the concrete beam,which is beneficial to improve the structural economy.The difference between the longitudinal and transverse flexural rigidity is not great,but the torsional stiffness reduction need to pay special attention.And the effect of the diaphragm on the torsionalrigidity is studied.It is concluded that although the torsional rigidity of the structure can be improved but the increase is limited.In the study of the natural frequency,it is found that the torsional frequency of the corrugated steel web box girders mainly occurs in the higher order,higher than the structural frequency,which can still be considered to have high torsional rigidity.