Damage Performance Of Unbonded Prestressed Beams Under Corrosion And Freeze-thaw

In many areas of our country,the corrosion and freezing and thawing of steel bars are the two main factors that cause the failure of concrete structure.The construction of reinforced concrete as the main body will cause different degree of damage after many years of service,which seriously affects the structure Carrying capacity.In recent years,although the relevant damage factors on the degradation of concrete structure of the study,but the corrosion and freezing and thawing under the joint action is relatively preliminary,sporadic,and thus continue to carry out and improve the concrete structure of the relevant damage test and basic theory research is becoming more necessary.In this paper,based on the freeze-thaw cycle and steel bar corrosion test of unbonded prestressed concrete beams,the related damage evolution rate of the structure is continued on the existing research results of the research group,and the related results will have stronger physical background And practical value.In this paper,the corrosion resistance mechanism of the steel bars and the freezethaw damage process of the composites have been more intuitive and obvious,and the different corrosion rates are different.The number of freezing and thawing can cause different degree of damage to the component,the main research content is:(1)Three-point static loading test was carried out on the unbonded prestressed beams subjected to corrosion and freezing and thawing under various experimental conditions.The deflection,crack width,and failure of the structure were recorded strictly in accordance with the relevant regulations,Mainly on the freeze-thaw cycle after the failure of concrete beam shape test and theory of the combination of analysis.(2)The definition of fracture toughness,fracture energy,crack propagation rate and derivation of related formulas in unbonded prestressed beams are mainly described.These parameters are the evaluation indexes of concrete damage fracture and make important theoretical basis for the analysis of the damage behavior of unbonded prestressed beams.(3)After the three-point static loading test on the unbonded prestressed beam subjected to corrosion and freeze-thaw cycles,the main crack propagation rate of the specimen is analyzed,including the main crack height and width,and the formula The fracture toughness and fracture energy of each beam are expounded,and then thefracture toughness and fracture energy of the beam are expounded and studied.The regression equation of the maximum width,fracture toughness and fracture energy of the main fracture is established under the coupling of corrosion and freezing and thawing cycles The(4)The damage analysis of the unbonded prestressed concrete beam is carried out.The damage degree of the test beam is defined by the loss rate of fracture energy and fracture toughness.Then,the damage degree of the structure under different damage factors is analyzed,Damage evolution model of unbonded prestressed beams under freeze-thaw cycles.Through the establishment of the equation,it can be used as reference in the future practical engineering to predict the damage and deterioration performance of the concrete structure,and provide the basis and reference for the study of the durability of the unbonded prestressed concrete structure under the coupling of corrosion and freezing and thawing.