Relationship Model of the Moment Capacity of GFRP Sheet Strengthened RC Beams to the Duration of Sea Water Exposure

Fiber Reinforced Plastics (FRP) has been widely applied in many purposes in civil engineering fields. Especially, FRP sheet is very suitable for strengthening of the existing structures. FRP sheet may be applied in various environment conditions of the structures. Many structures have to resist aggressive environment condition such as sea water exposure. Study on the effect of sea water exposure to the moment capacity of the concrete beams strengthening using GFRP sheet is important regarding to the effectiveness of strengthening. An experimental program has been conducted to find out the relationship of the moment capacity of the RC beams strengthened using FFRP sheet to the time of sea water exposure. A series of experimental specimens were prepared to be exposed in the sea water for 24 months. The beam specimens had the dimension of 3000 mm length with 150 x 200 mm of cross section. The specimens were reinforced by steel bars based on the under reinforced condition. The strengthening of the RC beams was conducted after 28 days of curing. The strengthened specimens were then submerged into sea water. The investigation on the moment capacity was conducted for 6 month, 12 month, 18 month and 24 months of exposure, respectively. Results indicated that the moment capacity of the beams decreased as the increasing of the exposure duration. Based on the experimental data, a relationship model of the effect of sea water exposure duration to the moment capacity was developed. The developed model may be used to predict the effect of sea water exposure to the moment capacity of GFRP sheet strengthened RC beams in design.