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

Ahmed E1 Refai

Third Advisor

Shamim A. Sheikh

Abstract

This research examines the viability of using different composite-based systems to upgrade the shear resistance of shear-deficient reinforced concrete T-girders. The research comprised experimental testing and analytical investigation. Test parameters included the retrofitting system; externally-bonded carbon fiber-reinforced polymer (EB-CFRP) laminates with or without a mechanical end anchorage (MA) and embedded through depth glass fiber-reinforced (ETD-GFRP) rebars; amount of internal stirrups; no stirrups, limited amount of stirrups with spacing s1 = 0.6d, higher amount of stirrups with spacing s2 = 0.375d; and initial shear damage prior to retrofitting; no damage, pre-cracking, and pre-failure.

The shear strength gain for the non-damaged specimens decreased as the amount of stirrups increased. The EB-CFRP system without MA increased the shear resistance by 17, 19, and 13%, for the specimens without stirrups, with stirrups spacing S1 and S2, respectively. The inclusion of the MA in the EB-CFRP system increased the former shear strength gains to 64, 36, and 32%, respectively. The shear strength gains provided by the ETD-GFRP system were comparable to those provided by the EB-CFRP with MA.

The presence of shear damage prior to retrofitting significantly reduced the strengthening effectiveness. For the pre-cracked specimens with the lower amount of stirrups, only 11, 27, 11% shear strength gains were recorded after retrofitting with the EB-CFRP solely, EB-CFRP with MA, and ETD-GFRP systems, respectively. The EB-CFRP system without MA was not successful in restoring the shear resistance of the pre-failed specimens. The EB-CFRP with MA and ETD-GFRP systems fully restored the shear resistance of the pre-failed specimens. The shear resistance of the pre-failed specimens retrofitted by the EB-CFRP with MA was 1.1 to 1.4 times the original shear resistance compared to 1 to 1.1 times for the pre-failed specimens retrofitted with the ETD-GFRP system.

In the analytical investigation, the accuracy of five different international guidelines/standards and two recent analytical models published in the literature to predict the contribution of the EB-CFRP system to the shear resistance have been assessed. The validity of a recent analytical approach published in the literature to predict the contribution of the ETD-GFRP system to the shear capacity has been demonstrated.

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