STUDY ON REINFORCED CONCRETE SLABS STRENGTHENED BY CARBON FIBER SHEETS

The existing reinforced concrete (RC) slabs on highway bridges have to sustain increasing active loads and suffer from fatigue deterioration. Most of the deterioration patterns of RC slabs identified by inspection show the following four basic appearances: Stage 1: Transverse cracking (perpendicular to bridge axial direction only); Stage 2: Orthogonal double direction cracking; Stage 3: Honeycomb cracking; Stage 4: Holes with concrete dropping. From past research on the damage of RC slabs, it has become clear that the crack progress is an important factor to determine the level of damage. RC slabs designed with the pre-1971 version of the Specifications for Highway Bridges, have an insufficient thickness and amount of reinforcement when considering fatigue vulnerability. Meanwhile, it is desired that RC slabs designed with post-1971 Specifications should also be reinforced to suit the present version issued in 1996. Hanshin Expressway Public Corporation (HEPC) had already repaired most old slabs with the epoxy bonded steel plate method to increase durability. At present studies are being carried out on a new strengthening method with carbon fiber (CF) which has been developed recently as a new construction material according to the need for minimum addition of dead load to the superstructures. The paper describes a design method for RC slabs strengthened by CF sheets proposed according to the results of experiments and analysis on the improvement of their durability. (a) For the covering entry of this conference, please see ITRD abstract no. E204151.