Causes and Control Measures of Wire Breakage in Prestressed Construction

In prestressed concrete construction, breakage of PC strand and prestressed wire directly interrupts tensioning operations. In severe cases, the entire tendon must be re-threaded, with potential structural safety implications. Based on extensive engineering service experience, this article summarizes the causes of wire breakage in three categories — material, handling, and equipment — and presents corresponding control measures for reference by construction and supervision personnel.

1. Material and Storage Defects

A considerable proportion of wire breakage can be traced to storage and transport before the material reaches the site. Common cases include: batch variation in tensile strength or elongation of PC strand, with individual coils below specified performance; plastic deformation caused by crushing under lifting gear or coiling damage during transport and handling; corrosion pits formed by moisture exposure during outdoor storage; and surface scratches inflicted by machinery during stacking or transfer. Such defects are difficult to detect before tensioning and initiate fracture at the weakened section under high stress.

Solutions: On delivery, verify the mill certificate and batch identification, and perform sampling tests of mechanical properties by batch. Store coils elevated from the ground with waterproof covering; material with excessive corrosion or scratching shall be rejected. Our PC strand and prestressed wire undergo batch-by-batch mechanical testing prior to shipment, with inspection certificates supplied with each delivery, together with moisture-proof packaging and reinforced securing, to control material quality at the source.

2. Non-Standard Handling Operations

Field breakage frequently originates from handling details: unreeling without a strand stand, producing kinks and whip damage; threading without chamfering the duct opening, so the strand is repeatedly abraded against concrete edges; or uneven force distribution during manual dragging, causing excessive local bending. Such damage is barely detectable before tensioning yet becomes the fracture origin once tensioning stress is applied.

Solutions: Use a PC stand for unreeling and control the pay-off speed; inspect the smoothness of duct openings before threading; apply force uniformly when dragging. We provide construction technical guidance documents to help customers standardize on-site procedures.

3. Equipment Mismatch

Wire breakage during tensioning is generally associated with equipment condition and compatibility: jacks not calibrated at the prescribed interval and unstable oil pressure; failure of synchronized multi-strand tensioning, causing certain strands to take load first and be instantaneously overloaded; anchorage size not matching the strand diameter, resulting in wedge indentation or slippage on the wires; and misalignment of the bearing plate, inducing eccentric loading and stress concentration. In addition, corrosive environments reduce the effective steel cross-section, and direct contact between immersion vibrators and the strand during concreting introduces further local disturbance — both constitute latent breakage risks.

Solutions: Calibrate jacks and pressure gauges at the prescribed interval before tensioning; verify the correspondence between anchorage specifications and strand diameter; ensure proper alignment of bearing plates. We supply a full range of prestressed anchorages and can provide selection recommendations matched to the strand specification in use. For coastal and corrosive environments, we recommend galvanized or epoxy-coated products, with our technical team available to assist in verifying tensioning parameters.

Conclusion

Wire breakage on site is typically the combined result of material defects, improper handling, and equipment malfunction. The effective control path is to select material suppliers with consistent quality and batch traceability at the source, while enforcing strict operational procedures and equipment management on site. As a source factory, we provide batch-consistent PC strand, prestressed wire, and matching anchorages with full technical support. Should you encounter wire breakage in your project or require customized specifications, please contact us by phone or email through our website.