Civil Engineering ETDs

Moneeb Genedy

Publication Date

7-12-2014

Abstract

Since Fiber Reinforced Polymer (FRP) was introduced to the construction field, strengthening of reinforced concrete beams using FRP laminates became a common repair and retrofit technique. Traditionally, Reinforced Concrete (RC) beams are strengthened by adhering FRP laminates to the tension side of the beam to work as an additional tensile reinforcement. Although this technique has been proven as an efficient strengthening technique, in many cases reaching the tension side of the beam is challenging due to the existing of ducts, pipes or cables underneath the beam in buildings. This challenge is magnified in bridges crossing water canals or major highways where expensive scaffolding is needed to reach the underside of beams. This research investigates a flexural strengthening system for T-beams that avoids the need to reach the tension underside. In this technique, the top 51 mm cover of the beam is removed, and Carbon Fiber reinforced polymer (CFRP) laminates are attached to the existing concrete surface after which an Ultra High performance Concrete (UHPC) overlay is then cast on top of the CFRP. The hypothesis of this technique is that the very high compressive strength of the UHPC overlay will push the neutral axis up and allow the CFRP laminates to be under tension. Four RC beams were cast and tested under four-point bending until failure. The proposed strengthening technique showed an increase in the load capacity while strengthening beam with only UHPC overlay had no significant effect on the load capacity of the beam. Unlike the expected, replacing the UHPC overlay with Latex Modified Ultra High Performance Concrete (LMUHPC) overlay did not increase the bond between the overlay and the T-beam and resulted in low load capacity. These results indicate that the proposed technique might be beneficial for shallow to medium T-beams and slabs.

Keywords

UHPC, FRP, Strengthening, RC Beams

Sponsors

Department of Energy

Document Type

Thesis

Language

English

Degree Name

Civil Engineering

Level of Degree

Masters

Department Name

Civil Engineering

First Committee Member (Chair)

Maji, Arup

Second Committee Member

Shen, Yu-Lin

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