Civil Engineering Department at UOT granted M.Sc. in Structural Engineering for the student (Mustafa S. Alwan) on 24/5 /2022, in the high study hall, about:

“Influence of Ties on the Behavior of Short and Slender RC Columns Strengthened by External CFRP"

This research aims to study the effect of changing the spacing between steel reinforcement collars on the structural performance of short and thin reinforced concrete columns externally reinforced with CFRP system. To achieve this goal, twenty-four (24) models of reinforced columns were poured using ordinary concrete, which were configured and tested until failure under the influence of a pure axial stress load. The main variables that were adopted in this study are: (a) the ratio of shaft thinness, (b) the distances between the steel rings, (c) the level of external reinforcement provided by the CFRP system.

Through investigations of all the above columns, it was found that the increase in the internal side confining pressure provided by the steel reinforcing collars has a significant positive effect on the maximum bearing capacity of each column and this applies to the short and thin columns. For short poles without any external reinforcement (control poles), reducing the spacing between steel reinforcing bars from 160mm to 125mm and 90mm increased the maximum bearing capacity of the poles by 5.77% and 28.90%, respectively. Moreover, the results of the tests showed that the carbon fiber-reinforced polymer system works effectively in enhancing the structural performance of short and thin columns, and the improvement rate provided by this system is affected by the distance between the steel reinforcement bars, the coverage ratio, and the proportion of the shaft. For example, in comparison with the control columns, the maximum bearing capacity of the short columns in which the spacing between the steel reinforcing bars was 90 mm and the ratio of the outer covering with carbon fiber-reinforced polymers (25, 50, and 100 %) increased (17.26 and 39.04%,74.99%) , respectively. As for the similar thin columns in terms of the interstitial distances of the steel reinforcement bars and the percentage of external coverage with polymers reinforced with carbon fibers, the increase in the maximum bearing capacity was (16.29, 36.80, and 71.63 %) respectively.

The discussion committee consisted of:-

• Prof. Dr. Ammar Abbas Ali / the head.
• Prof. Dr. Wamid Ghassan Abdul-Hussein / member.
• Prof. Dr. Ziad Abdul-Nabi Khudair / member.
• Dr. Qais Fouad Sarsam / supervisor.
• Dr. Raed Ibrahim Khalil / supervisor.