The Application Research Of Unbonded Partially Prestressed Concrete Beam In Railway Bridge

Compared with normal prestressed concrete, unbonded partially prestressed concrete has a lot of advantages, it is used extensively in highway and railway bridge engineering. Because the reinforcing bar and surroundings concrete can have opposite slip in unbonded prestressed concrete, Lead to stress and deflection differing from bonded prestressed concrete structure.This thesis combining with unbonded partially prestressed concrete beam model, according to static load test, destructive test and the fatigue test, has deeply reaearch on unbonded partially prestressed concrete calculation theory and behavior. The groundwork is as follows:1. Test research on beam model. In order to discuss the performance under static load and repeated load, tests on beam models have bean done. It provides related parameter and evidence for application in railway of unbonded prestressed concrete beam.2. Research on structure performance. Transformation of stress with loads has relation on section distortion, not with section position. Unbonded partially prestressed concrete beam has the same distortion performance as bonded partially prestressed concrete beam. Under design load, beam models have good compression capability. Rational design can control stress, strain and crack availably.3. Research on stress increment and control stress under archorage. It can measure stress of prestressing strand through sensors. Because of friction, stress increment of prestressing strand is not very big, smaller than calculated results. With the load increasing, stress increment increases obviously. At the last, strand snaped, and the beam models destroyed.4. Research on calculational method of ultimate load bearing capacity and stress in service step. Computation of ultimate moment,...