Study on Damage Evolution and Mechanical Performance of PCCP Before and After Internal Steel-Cylinder Repair Under Multiple Broken-Wire Conditions.

To evaluate the damage evolution of prestressed concrete cylinder pipe (PCCP) with broken wires and the effectiveness of internal steel-cylinder repair, a three-dimensional finite element model was established using ABAQUS and calibrated with a full-scale hydrostatic-pressure test. Test-calibrated parametric simulations considered three nominal wire breakage levels (5%, 15%, and 25%) and two damage locations: the pipe midspan and pipe-end socket region. Concrete-core damage, original steel-cylinder strain, strengthening-cylinder response, and grouting-layer load transfer were compared before and after repair. The unrepaired pipe-end socket region showed a lower numerical nonlinear-transition pressure and stronger damage propagation because of geometric discontinuity. Increasing wire breakage reduced the nonlinear-transition pressure of the concrete core and increased the original steel-cylinder strain. After internal steel-cylinder repair, the structural responses converged across the investigated damage cases. At 1.2 MPa, the calculated strain reductions between corresponding unrepaired and repaired numerical configurations were 77.2-91.0% for the original steel cylinder. At the maximum applied pressure of 1.6 MPa, the modeled maximum original steel-cylinder strain was 459.11 με. The repaired configurations exhibited reduced strain demand and coordinated load sharing over the investigated monotonic internal-pressure range. The test program ended at 1.6 MPa without an ultimate-failure loading stage.