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This study evaluates two different types of techniques for concrete hollow-block sections reinforced with traditional steel rebars and wire meshes, and compares their structural behaviour to that of an ordinary reinforced concrete beam section. The comparisons are based on the responses both before and after they were repaired with glass fibre reinforced polymers (GFRP). The specimens were subjected to concentrated loading up to initial failure. After failure, the specimens were repaired and loaded once again until ultimate failure. It was shown that the success of the repair by GFRP depended on the mode of failure of the hollow-block concrete beams.

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This paper presents an experimental study on seismic repair of damaged square reinforced concrete columns with poor lap splices, 90-degree hooks and widely spaced transverse bars in plastic hinge regions according to ACI detailing (pre.1971) and (318-02) using GFRP wraps. Three specimens were tested in “as built” condition and retested after they were repaired by glass fiberreinforced plastic sheets. They were tested under numerous reversed lateral cyclic loading with a constant axial load ratio. FRP composite wraps were used for repairing of concrete columns in critically stressed areas near the column footings. Physical and mechanical properties of composite wraps are described. Seismic performance and ductility of the repaired columns in terms of the hysteretic response are evaluated and compared with those of the original columns. The results indicated that GFRP wraps can be an effective repair measure for poorly confined R/C columns due to short splice length and widely spaced ties with 90-degree anchorage hooks. Both flexural strength and ductility of repaired columns were improved by increasing the existing confinement in critical regions of them.

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The use of epoxy-bonded FRPcomposite for structural repair is emerging as an efficient and cost-effective technique for restoring and upgrading the capacity of concrete structures. Considerable researches have been reported in the last decades on the mechanical behavior and failure modes of the FRPstrengthened RC elements but actual data on its durability are scarce. This study intends to examine the durability of concrete specimens strengthened with FRP laminates under accelerated laboratory conditions and mimic harsh environmental situation which is the penetration of chloride ions. In this study three groups of specimens were examined. Each of these groups includes several concrete cylindrical specimens full confined with FRP laminates for investigating different types of fiber (Glass and Carbon), number of fiber layers and temperature influences. Furthermore, an apparatus was fabricated to simulate wetting and drying cycles for the second group of specimens. Moreover group III specimens were placed in a marine environment for 3 years to monitor their performance. Test results show that addition of FRP laminates reduces chloride ions penetration up to 70 percent. Results also indicate that although chloride ions penetration decreased the ultimate strength of cylindrical specimens up to 11 percent but FRP strengthened specimens achieved their initial strengths. Moreover wetting and drying cycles reduced the strength of cylinder specimens up to about ten percent especially in the high temperature laboratory condition.