Bonded laminates for retrofitting of reinforced concrete beams

Abstract

The RCC structures constructed these days suffer damage due to a large number of factors like improper design, faulty construction, overloading, change in codal provisions, non-engineered construction, explosions, wear and tear, earthquake, fire etc. A major part of the funds used in the construction industry is being spent on repair, retrofitting and rehabilitation of such structures. Retrofitting is different from repair or rehabilitation. It is basically a process of strengthening and enhancement of the performance of deficient structural elements in a structure or of the structure as whole. The extent of damage to a structure can be assessed with the help of modern non-destructive testing techniques and methods. Once it is established that a structural member is unable to resist the design loads, the structure has to be repaired/strengthened to make it functional. The repairing or strengthening of existing structures poses higher challenge to a civil engineer in comparison to design and construction of new structures. Specific technology has to be designed and developed to rehabilitate the damaged structures, and to improve the performance for new functions, of old undamaged structures. Thus, the technique to be used should be simple in execution; offer better performance when handled by less experienced workers, and must use materials that are readily available, durable, strong and economical. Retrofitting of deficient buildings can be done by increasing the strength, stiffness and/or ductility of its specific constituent elements or of the whole building. For any building, depending upon the requirement, a combination of the above may also be selected. Retrofitting of individual members or elements is referred to as local retrofitting. This retrofitting technique is normally adopted when, after the evaluation, only a few of the building s elements are found to be deficient. For local repair and retrofitting a large number of techniques are being used.