Nonlinear Mechanical Behavior Analysis Of The Cracked Prestressed Concrete Beam

With the rapid development of transportation in China,prestressed concrete T beam bridges are widely used in railway and highway bridges.During the operation of this type of bridge,a considerable number of bridges suffered different degrees of cracking damage,which is increasingly serious,which has a direct impact on the safety,usability and durability of the structure.This paper studied the static loading of 2 partially prestressed concrete T beam,combined with finite element numerical simulation,obtain the deflection,strain,crack load in the process of development of structural response of prestressed concrete T beam after cracking and crack distribution and mechanical properties,the main research work is as follows:(1)In this paper,the reason,mechanism and method of crack analysis of concrete members are summarized,and the method of simulating crack by finite element method and calculating method of crack width by finite element method are introduced in detail.(2)The indoor model tests on prestressed concrete simply supported T-beams are carried out.The deflection,stress-strain,crack spacing and crack width are obtained.The generation and development of cracks under various loads are studied.By analyzing and calculating the experimental data,the following conclusions are obtained: The height and width of cracks increase with the increase of load level,and the increase of both is interactive;There is a certain relationship between the statistical parameters of load and crack characteristics(average crack height,maximum crack width,average crack width,average crack spacing and total crack width),Except that the relationship with the average crack spacing is not clear,the relationship between the other parameters and the other parameters is linear;The cracking load,yield load,ultimate load,crack spacing,number and maximum crack width of the two test beams are very different,but the rules of crack generation and development are approximately the same.(3)The basic theory of finite element calculation software ABAQUS is introduced briefly.The finite element simulation of the loading process of the specimen is carried out by using the finite element software,and the variation of mid-span deflection,cross-section stress and crack development during the loading process of the specimen are analyzed.Compared with the experimental results,the results are in good agreement with the experimental results.It is proved that it is reasonable and feasible to study the nonlinear mechanical behavior of post-crack prestressed concrete beams by using the numerical simulation technique of ABAQUS.(4)A new model beam is designed on the basis of the front.The finite element software is used to analyze the mechanical performance parameters of the model beam,and the conclusions are as follows: Increasing the reinforcement ratio of unprestressed tendons can effectively improve the bearing capacity of the beam,but the ductility of the beam will be reduced;The cracking moment and ultimate moment of beam can be improved significantly by increasing the reinforcement ratio of prestressed tendons;Increasing the axial compressive strength of concrete can significantly improve the stiffness of the beam.