College of Engineering

A master thesis was discussed in Department of Civil Engineering / College of Engineering at University of Mosul entitled “Nonlinear Investigation of Enhancing Torsional Strength of RC Beams By Near-Surface Mounted (NSM) Reinforcement” submitted by postgraduate student (Mashael Abdulraheem Madah), supervised by Prof. Dr. Mohammed Najim Mahmoodon Monday, Dec. 13, 2021.The thesis presents a nonlinear finite element analysis of thirty-eight rectangular cross-section RC beams subjected to pure torsion. A numerical study carried out through a simulation of RC beams designed to fail in torsion presented by experimental study. A verification procedure was performed on three specimens by finite element analysis with ANSYS APDL software.The studied parameters included three strengthening methods such as the wrapping by CFRP sheets for twenty-two models besides the strengthening by near-surface mounted steel and carbon bars for sixteen specimens. The strengthening by CFRP sheets included two secondary variables such as the wrapping configuration and a number of confinement layers. While the strengthening by near-surface mounted bar included spacing variable beside the number of the used bar.The results revealed that use of full wrapping with one layer enhanced the ultimate torque when compared with the control beam. The strengthened beams showed enhancement in torsional strength when compared with the control specimen. The use of U-shaped jacket provided enhancement in the ultimate torque higher than the full wrapping and less rotation. Replacing the U-jacket by U-shaped strips revealed improvement in the ultimate torque less than the U-jacket.The ductility of the tested beams showed that the strengthening enhanced the ductility of the twisted Reinforced Concrete Strengthened Beams. The ductility values varied according to the method of used strengthening, as it showed the highest values of the beam that was reinforced with CFRP sheet more than the NSM by CFRP bar and steel rebar. Concerning the NSM strengthening method, carbon CFRP mounted rebar gave the highest value of ductility. The energy absorption showed that the varying in the values according to the strengthening method were the more enhancement in the energy absorption for the CFRP sheets is higher than offered by NSM carbon bar and steel rebar.