Firas Al-Mahmoud

Reinforced Concrete Beams Strengthened with NSM CFRP Rods in Shear

This experimental research aims to investigate the possibility of using Carbon Fiber-Reinforced Polymer (CFRP) rods to strengthen in shear concrete structural members with the Near Surface Mounted reinforcement (NSM) technique. Seven reinforced concrete beams were tested in flexure with or without traditional shear reinforcement. Carbon-epoxy pultruded FRP (CFRP) rods with 6 mm in diameter were used. The possibility of using a mortar as filling material with surface pre-conditioned CFRP rod is investigated and compared to resin performance. Results show that NSM technique is very efficient to strengthen reinforced concrete beam in shear. Using the resin instead of mortar as the filling material still increases the efficiency of the shear strengthening but the gain is only moderate. The experimental results are compared with existing analytical models.

Modelling of flexural behaviour of RC beams strengthened with NSM CFRP rods including serviceability

The proposed model calculates the deflection of carbon fibre-reinforced polymer (CFRP) strengthened beams. In this model, the beams were strengthened before loading, so in an uncracked state. The calculation before cracking uses conventional existing models. The calculation of the deflection after cracking is based on a non-linear Macro-Finite-Element (M.F.E.). This M.F.E. is a beam Finite Element characterised mainly (for the bending problems) by its homogeneous average moment of inertia. The typical global behaviour of beams strengthened by NSM rods s was modelled as well as repeated loading cycles. The model is validated experimentally on two CFRP strengthened concrete beams with two sections of CFRP rods subjected to four-point flexure under repeated loading cycles after cracking and then a constant loading rate until failure. Results show that the model gives good predictions of the bending stiffness of the beam during the loading cycle and the permanent residual deflection after unloading due to crack propagation.