Anes Bouchair

Date of Award

6-2014

Document Type

Thesis

Degree Name

Master of Science in Civil Engineering (MSCE)

Department

Civil Engineering

First Advisor

Tamer El Maaddawy

Second Advisor

Bilal EI-Ariss

Third Advisor

Sami Rizkalla

Abstract

This research work aims at evaluating the effects of corrosion on flexural response of simply supported reinforced concrete (RC) T-Beams strengthened with near-surface-mounted carbon fiber-reinforced polymer (NSM-CFRP) strips. The research comprised experimental testing and analytical modelling. Test parameters included concrete grade, amount of NSM-CFRP strips, presence of U-wraps along the beam span, and time of corrosion exposure. A total of eighteen reinforced concrete beams with a T-shaped cross section were tested. Fourteen beams were strengthened in flexure and four beams were not strengthened to act as benchmarks. The strengthening regime included installation of either two or four NSM-CFRP strips into grooves precut onto the tensile concrete cover. In some specimens, the NSM-CFRP longitudinal strips were supplemented by intermittent U-shaped composite wraps along the beam span. Eight beams were not corroded and ten beams were subjected to accelerated corrosion for 30 and 100 days that corresponded to measured tensile steel mass losses of 5% and 15%, respectively. Three of the non-corroded beams had a concrete compressive strength of 60 MPa whereas all other beams had a concrete compressive strength of 25 MPa.

The NSM-CFRP strengthening system significantly improved the beam’s flexural capacity and stiffness. The gain in flexural capacity was more pronounced for the beams with the higher concrete grade. Increasing the amount of NSM-CFRP strips further improved the flexural capacity but the additional gain was not proportional to the added amount of NSM-CFRP strips. Corrosion damage and cracking reduced the flexural strength of the beams strengthened with the NSM-CFRP strips without U-wraps. The integration of U-shaped composite wraps in the strengthening regime prevented premature peeling-off of the concrete cover and the enclosed NSM-CFRP strips. No reduction in flexural strength was recorded for the corroded beams strengthened with the NSM-CFRP strips together with U-wraps. The residual strengths of all strengthened-corroded beams were substantially higher than that of the control beam.

An analytical model that can predict the flexural capacity of corroded RC T-beams strengthened with NSM-CFRP strips has been introduced. The predicted load capacity of all beams was within a 15% error band which demonstrate the model’s accuracy and validity.

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