Experimental Study On Geometric Nonlinearity Of Carbon Fiber Thin-walled Box Girder

Carbon fiber reinforced polymer (CFRP) has been widely applied to various fields，forexample building, aviation, automobile, entertainment, fitness equipment and so on. The mainreason is that carbon fiber composite material not only has good mechanical properties, butalso the very good function. In recent years, carbon fiber reinforced polymer is often used forthe repair or reinforcement of structure, and get good results, which caused many scholarsbeing interested in the deeper exploration of the CFRP. Now the CFRP thin-walled box girderapplied to the actual structure becomes a kind of vision, however the current research for thecarbon fiber composite materials of box beam is still in its infancy. People has made someachievements in many aspects, but there are still many aspects of the theory is not enoughmature, some specification is not perfect. On the base of the introduction above this articlewill do some discussions on nonlinearity of the carbon fiber composite thin-walled boxgirder with the help of large finite element software Ansys and experiment, in order toreference for engineering practice.In order to study more to the composite box beam’s geometric nonlinearity: Firstlysimply introduce the definition of a composite material, the advantages of application of thecarbon fiber composite materials, succinctly introduce some disadvantage of CARP, finallyintroduce the developing situation of the composite materials, the widely reinforcement ofthe composite material in the field of construction, especially in bridge reinforcement,cable-stayed bridge and cable, the application of the prestressed;Secondly introduces themain mechanical properties of box beam, and puts forward the concept of shear lag effect,also illustrates the influence of shear lag effect to the engineering structure, summarizes somepredecessors’ research methods on the shear lag; Then puts forward the concept of geometricnonlinearity, and points out the importance of the research of structure geometric nonlinearity,finally summarizes the analysis methods to the geometric nonlinear; Thirdly,this part ismainly do contrast with the third chapter. With the help of the Ansys, the author do somenumerical simulation to the Carbon fiber thin-walled box girder having different layers anddifferent spans, gather data and draw a conclusion of the geometric nonlinearity and shearlag effect.Finally the fourth part, firstly do the tensile test to the Carbon fiber layer board, getmodulus of elasticity and poisson’s ratio of material, in order to lay the foundation for thethird test and the fourth chapter; the second experiment is doing tensile test to the laminatedplates having different layer Angle, from the test we can get the elastic modulus and poisson’sratio of the Laminated plates having different layer Angle. The finally test is do the bend-pressure test to thin-walled box girder made of Laminated plates having the different layer,in order to study the changes about geometric nonlinearity and the change of the shear lag effectof box girder box under the change of the layer angle and span.The paper do the research to the Composite box girder from two aspects of numericalsimulation and test Through The Analyzing, we can know that Layer point of view, the spanof the box girder, external load make a big difference to the Composite box girder, and haveopposite Effection,in order to remove or minish the effect,we should consider this problemfrom all aspects(Layer point of view, the span of the box girder, external load), make the finaldesign of thin-walled girder more economic and reasonable and beautiful.