STRENGTHENING BY EXTERNAL PRESTRESSING

Compared with conventional reinforced concrete structures, prestressed concrete structures are assumed to be more corrosion resistant due to the use of high-strength materials and the crack-free nature brought about by precompression. In spite of these advantages, stress corrosion in prestressed concrete structures can result in premature and catastrophic failure even when epoxy-coated reinforcement is used. Further, the deterioration of embedded prestressing reinforcement may not be visible as external distress in the concrete, resulting in degradation that goes undetected and unremediated until becoming severe. When prestressed concrete structures degrade prematurely due to corrosion of the prestressing steel, reliable methods of repair and strengthening must be available to minimize the economic consequences. One such method is the use of external prestressing. In this article, an investigation is described into the effectiveness of this method for various levels of internal prestressing steel deterioration.