STRENGTHENING HEAT DAMAGED REINFORCED CONCRETE BEAMS USING GLASS FIBER-REINFORCED POLYMER (GFRP) LAMINATES

A series of 21 reinforced concrete T- beams of length 1400 mm were cast using normal strength concrete. After 90 days of ageing, the beams were heated to 600°C and 900°C temperatures in an electric furnace. While three control beams were treated at room temperature, eighteen beams were heat damaged. The heat damaged beams were strengthened with FRP laminates and then tested until complete failure. Two different strengthening patterns of glass fiber reinforced polymer (GFRP) strengthening materials were used. The strengthened beams were then tested in a loading frame under 4 point loading condition. The load-deflection curves for the beams were examined to evaluate the capability of various strengthening patterns. Structural performance of various strengthening patterns were gauged in terms of failure mode, flexural strength, secant stiffness and the energy absorption capacity i.e. area under the load-displacement curve. It was observed that the beams exposed to different temperatures experienced a reduction in ultimate load carrying capacity ranging from 14 % to 61%. The secant stiffness and energy dissipation were reduced in the range of 34% to 56% and 10% to 41% respectively. The study shows that GFRP wraps were quite capable of restoring the flexural strength of heat damaged beams.