Study On The Application Of External Prestressing Method In Engineering

External prestressing is one of the important branchs of post-tensioned prestressing system,mainly used in the reinforcement of engineering construction and bridge engineering.the technology of external prestressingis arranged outside the structure component of prestressed tendons,applying an external prestressing method for prestressed concrete,its essence is to use high strength reinforcement steel bar and steel strand or high strength steel wire as material,through tensioning prestressed tendons and setting up the device for applying externally prestressed structures or components,to offset part of the internal force of externally applied pipe load,thus improving the use of concrete beams and improve the ultimate bearing capacity,crack resistance and deformation resistance.Scholars at home and abroad of externally prestressed concrete structure research in a large amount of fine fatigue performance,but verification of externally prestressed concrete structure fatigue performance study is less.Taking Cargill Bio-chemical Co.,LTDSongyuan City jilin Prov.PRC,modified starch renovation project(modified starch workshop)as the background,the actual engineering reinforcement of the continuous beam is simplified to beam to simulate the actual working effect,the validation of externally prestressed reinforced concrete beam fatigue test and static load test,record the test beam carrying capacity,deflection,steel strand,steel and concrete strain and crack development and has carried on the detailed analysis;And fatigue and ultimate bearing capacity and checking,calculating the indicators meet the requirements of the current specification.and then verify the actual effect of the external prestressing method.The test results show that the externally prestressed beam after 820000 times of fatigue load,steering block,anchor system work performance is good,there is no failure,externally prestressed reinforced concrete beam fatigue resistance performance is good,can satisfy the practical production requirements.For designing institute such reinforcement project in the future work,and the external prestressed reinforcement technology,accumulated experience,provides the practical reference value,and has certain practical significance.Based on the results of this paper,the actual reinforcement project and fatigue tests were carried out similar when given a few main suggestions for future design institute using this method:(1)Steering block should be at least Q345 grade steel;(2)The anchored steel plate at the beam end should not be cantilevered and should be completely anchored to the ends or columns of the reinforced concrete beam;(3)if the test component T beam,and the use of two or more points loading will be much closer to the actual project,the test error will be smaller.