Date of Award

12-2014

Document Type

Thesis

Degree Name

Master of Science in Civil Engineering (MSCE)

Department

Environmental Engineering

First Advisor

Dr. Tamer EI Maaddawy

Second Advisor

Dr. Said EI Khouly

Third Advisor

Dr. Mark Green

Abstract

Installation of cutouts in existing reinforced concrete (CR) floor slabs to accommodate utility services reduces the slab load capacity and ductility. This research examines the effectiveness of using near-surface-mounted (NSM) carbon fiber reinforced polymer (CFRP) reinforcement to improve the flexural response of continuous RC slabs with cutouts. The study comprised experimental testing and analytical modeling. A total of eleven two-span RC slabs strips, 400 x 125 x 3800mm each were tested. Test parameters included the location of the cutouts, and amount and distribution of the NSM-CFRP reinforcement between the sagging and hogging regions.

Installation of a cutout in the sagging region reduced the load capacity and ductility index by 27% and 12% respectively. When the cutout was installed in the hogging region, a 23% of reduction in both load capacity and ductility index was recorded. The NSM-CFRP strengthening fully restored the original load capacity of all deficient specimens, expect one specimen with a cutout in the hogging region where only 90% of the original load capacity was restored. The enhancement in load capacity due to strengthening was in the range of 53% to 81% for the specimens with cutout in the hogging region. The ductility index of the specimens strengthened in the sagging region only was, on average, 16% lower than that of the control specimen, whereas for the specimens strengthened in the hogging region only, the ductility index was almost the same as that of the control slab. For the specimens heavily strengthened in both sagging and hogging regions, the ductility index was on average 40% lower than that of the control slab. A maximum moment redistribution ratio of 26% was recorded for the continuous RC slabs strengthened with NSM-CFRP.

An analytical model that can predict the load capacity of two-span RC slab strips containing cutouts and strengthened with NSM-CFRP has been introduced. The ratio of the predicted to measured load capacity was in the range of 0.74 to 1.02 with an average of 0.85, standard deviation of 0.09, and coefficient of variation of 10%.

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