Experimental Research On Fatigue Damage Performance Of The Composite Box-girder With Corrugated Steel Webs

The new corrugated steel webs with composite box-girder improves the traditional bottom plate of the corrugated steel composite box-girder to a flat steel bottom plate,which further reduces the weight of the structure,which contributes to the lightweight design of the structure and increases the span of the structure,and solves the cracking problems of the concrete floor in the past.The problem,while maximizing material performance,also increases construction efficiency,has clear technical advantages and broad application prospects.At present,Gansu Province is preparing to promote the use of this new type of structure.It is also necessary to conduct in-depth theoretical and experimental research on the new structure,especially the fatigue performance of the composite box girder.The use of experimental research is the most direct method of research and is currently urgently needed.Fatigue damage is the process of decay of structural materials caused by repeated loads.The whole process can be described as the initiation,propagation,macroscopic cracking,and fracture failure of fatigue cracks.The new type of corrugated steel webs with composite box-girder is a combination structure of welded steel box girder and concrete plate.The connection between the corrugated steel webs and the flat steel bottom weld seam,the shear connection between the concrete top plate and the corrugated steel webs and the direct bearing dynamic load.The concrete roof is the key part of the fatigue damage of the composite box-girder.In this paper,under the support of project project,the experimental research on the fatigue damage of composite box-girder with corrugated steel webs was carried out.The main research work is:1.From the development of composite box-girder with corrugated steel webs and the research progress of composite box-girder fatigue,a new type of box girder with corrugated steel webs is introduced and its structural characteristics and its effect on fatigue performance are analyzed;2.The traditional fatigue strength theory and the fatigue theory based on fracture mechanics are systematically elaborated,and the differences and respective characteristics of the two fatigue theory research methods are compared and analyzed;3.Taking a new type of 1-40 m corrugated steel web with composite box-girder as the structural prototype,the fatigue damage scale test model was designed and manufactured,and the fatigue damage model test was conducted on the test beam to determine the critical fatigue damage components of the test beam and the development rule of the fatigue damage.And analyze the influence to the composite box-girder;4.A general finite element software ANSYS was used to establish a suitable finite element model.By changing the structure and material parameters of critical fatiguecomponents,the influence of different influencing factors on the cumulative fatigue damage D of the composite box-girder was analyzed,and suggestions for improved design were put forward from the analysis results.