FAILURE MECHANISMS OF CONCRETE BEAMS REINFORCED WITH FRP FLEXIBLE SHEETS

During the last two decades a lot of research has been carried out on improving the load-bearing capacity of concrete beams by means of plate bonding, made up of either steel or composite plates, which were glued to the tensile surface of the beams. All test results revealed a notable improvement of the load bearing capacity of beams, but generally a brittle failure mechanism due to shear crack propagation inside concrete was observed. The recent availability of fabric composite materials, which have notably high mechanical properties, lets to quickly reinforce any shaped beam simply wrapping on it. Furthermore the composite material is directly constructed in situ, depending on the local demand of strength for the beam. Modeling of the overall mechanical behavior of the wrapped beams must take into account for the interface resistance between concrete and the composite sheet. To this regard it's extremely important to properly model the concrete behavior up to failure. Experimental results and numerical simulations will be presented along with a simple program which allows to design the reinforcement. The latter takes into account for the mechanical properties of material used and also it is able to detect the different type of failure that can appear on the repaired beam. (A) For the covering abstract see ITRD E104933.