Study On Mechanical Performance Of Prestressed Concrete Bending Members Under Freeze-thawing Environment

Prestressed concrete structure has been widely used in civil engineering, transportationengineering and hydraulic engineering gradually since it was invented by the Frenchengineer Freyssinet in1928, which has obvious superiority compared to the reinforcedconcrete structure. Based on “Research on durability test and life prediction of prestressedstructure under double index erosion environment” which is sponsored by National NaturalScience Foundation of China (item approved number:50878098) and “Research ondurability fatigue of prestressed concrete flexural members under freeze-thawingenvironment” which is sponsored by Ministry of Housing and Urban-Rural Construction ofthe People’s Republic of China (item approved number:2013-k4-26), the main researchcontents are as follows:Two experiments is carried out of five prestressed concrete flexural beams in thispaper which corresponding member number is L1, L2, L3, L4, L5: after0times,50times,100times,150times,200times freeze-thawing, the test of bending performance isexecuted. Based on the test process, phenomenon and results, these show the followingconclusions: with the time of freeze-thawing increasing, the relative dynamic modulus ofelasticity,the cracking load and ultimate load of beams decreases gradually, and the morefreeze-thawing times, attenuation is more obvious; the maximum crack width of ultimateloads increases, which indicates that the bearing capacity and crack resistance ofprestressed concrete flexural beams will decrease because of freeze-thawing effect.Refer to the research results of the mechanical properties of concrete afterfreeze-thawing action what has been achieved by the previous, the damage model ofprestressed concrete after freeze-thawing action is established. then, it’s applied to thesimulation analysis of finite element software, through the finite element software ofANSYS to simulate the bearing capacity of prestressed concrete flexural member afterfreeze-thawing action and comparing analysis results with test results we can know thefinite element in this paper has a certain accuracy and using ANSYS to simulate the bearingcapacity of prestressed concrete flexural member after freeze-thawing is feasible, sosimulation analysis can reflect the mechanical process well, but a more accurate finiteelement simulation also needs to use a more precise concrete constitutive model afterfreeze-thawing. Refer to the normal limit states checking method of prestressed concrete in Code fordesign of concrete structures (GB50010-2010), the changing rule of the midspan deflectionin using stage and maximum crack width of prestressed concrete suffered freeze-thawingaction, which vary with the number of freeze-thawing, has been studied. Then, reasonablesuggestions for short-term stiffness and maximum crack width calculation formulas ofprestressed concrete subjected to freeze-thawing action are given.This paper has investigated the bearing capacity and the normal limit states ofprestressed concrete flexural members after freeze-thawing action and has used finiteelement software of ANSYS to simulate, study results have important theoreticalsignificance and practical value for mechanical performance evaluation of already built ornew construction prestressed concrete structure in freeze-thawing environment in coldregion of our country.