The current thesis is dedicated to investigation of the possible increase of ductility and moment redistribution in RC frames strengthened with CFRP laminates. Eleven two-span RC beams connected to the top and bottom columns at the middle support were cast and tested, including two control specimens and nine strengthened specimens with CFRP laminates. The frame specimens were categorized in two groups: A and B. The beams in group A specimens had   tensile reinforcement and   compressive reinforcement at mid-spans and at middle support adjacent to the columns (   is the tensile balanced reinforcement ratio). Furthermore, the beams in group B specimens had   tensile reinforcement and   compressive reinforcement at mid-spans, and   tensile reinforcement and   compressive reinforcement around the columns at middle support. Small chamfers were provided at the junction of the columns to beams and L-shape FRP strengthening was performed at this region. To prevent debonding of the FRP laminates at the end region and at the beam-to-column junction, U-shaped FRP anchorages were provided on FRP laminates for all of the frame specimens at appropriate locations. Furthermore, mechanical anchorages of steel plates and bolts were added to the laminates for one specimen in each group.

   Test results showed that the load carrying capacity of the strengthened frames in groups A and B compared to that of control frames, had an increase of 16% to 33%, and 22% to 38%, respectively. Furthermore, the flexural capacity of the strengthened frames compared to that of control frames increased up to 20% and 58% at the faces of the columns and at the mid-spans, respectively; therefore, the flexural strengthening at the mid-span regions was more effective than that at the face-of-column regions. The curvature ductility factor in the strengthened frames without plates and bolts decreased 1.5 to 2.2 times compared to that in the control frames. Furthermore, the curvature ductility factor of the strengthened frames with plates and bolts had 1.5 times more reduction compared to the strengthened frames without plates and bolts. The moment redistribution of 20% to 56% was observed in all of the strengthened frames. The amount of moment redistribution in the frames strengthening with FRP only at the positive moment regions was more than that of the frame specimens with laminates at both positive and negative moment regions. Furthermore, the experimental results compared with the analytical results using Ansys software.

As a part of this study, the flexural rigidity method was developed for the estimation of the amount of moment redistribution in strengthened frames, using appropriate uncracked and cracked flexural rigidity at positive and negative moment regions. ...