Post-Tensioned Structure Modification

Engineering, manufacturing and installation services can be quickly mobilized into creative, efficient and cost-effective solutions.

Post-Tensioning Repair & Modification

The complexity of post-tensioning repairs requires a expertise with all elements of post-tensioning systems. STRUCTURAL TECHNOLOGIES has the most experience in repair and modification of prestressed concrete and is backed with the products of VSL post-tensioning products. Engineering, manufacturing and installation services can be quickly mobilized into creative, efficient and cost-effective solutions.

Corrosion of unbonded tendons is common for post-tensioned structures exposed to aggressive environments. Insufficient cover over the tendons and lack of corrosion protection at anchorages combined with exposure to chlorides through deicing materials and coastal air lead to the corrosion of post-tensioning systems.

Barrier cables used in parking garages are similar to post-tension cables in concrete slabs and are subject to the similar deterioration mechanisms. In some cases the failures occur more quickly since the cables are directly exposed to the elements and do not have the added protection provided by concrete cover. Replacing barrier cables and anchors requires the same expertise as repairing post-tensioning tendons.

Repairs to post-tensioning systems typically fall into two categories:

Structural Repairs

These repairs address system failures. Signs of structural post-tensioning system distress disclosed in the inspection can include the following and will require immediate repairs to restore strength and integrity to the structure:

  • Broken strands which can be seen coming out of the structure
  • End anchorage which has lifted out of the concrete
  • Cracking concrete which is running parallel to the strands
  • Excessive deflections
  • Punching shear cracks in slabs
  • Diagonal shear / flexure cracks in beams and joists

Preventative Maintenance

Regular inspection of strand systems for signs of distress is one of the best ways for a building owner to prevent costly repairs. Items to be considered in the inspection of post-tensioned structures:

  • Appropriate concrete cover over strands exposed to aggressive environments
  • Condition of protective grease and sheathing
  • Cracking near strands (P-T systems are designed to reduce or eliminate cracking, so any excess cracking may indicate a problem)
  • Condition of concrete at anchorage pockets
  • Rust staining on the concrete near strands
  • Grease staining on slab soffits




STRUCTURAL TECHNOLOGIES, a Structural Group company, is the exclusive designer and manufacturer of VSL post-tensioning and  construction systems in the United States. VSL systems have a well-earned reputation for their quality, reliability, and durability - and have been used throughout the world since 1956 to build, repair, and strengthen bridges, buildings, tanks, and special structures. For information on VSL products outside of the United States, visit the VSL International website

With companies dating back to 1902, Structural Group is firmly committed to its ongoing mission of making new and existing structures stronger and last longer. Through its companies, Structural Group delivers turnkey solutions that integrate technology, engineering, and construction. Structural Group provides specialty contracting services through our construction companies and state-of-the-art proprietary products and engineering support services through STRUCTURAL TECHNOLOGIES.

Learn more about Structural Group and its member companies.

VSL is the registered trademark of VSL International Ltd.