الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
The research work could be divided into three phases aimed at he
investigation of new repair materials and techniques used to repair distressed RC beams subjected to flexural load. Phase I provides a comprehensive study of the suggested repair materials under consideration. In this part we focused on a modified Polyester resin subjected to different temperatures for different
durations. The modified polyester resin represents an approach to the materials that have significantly high tensile strength if it is compared to the normal concrete mixes. The results showed that the maximum compressive and tensile strengths are obtained when the modified polyester resin specimens cured at 60ºC for 4 hours. Also, the dual action of time and temperature can be used to obtain better mechanical characteristics.
Phase Ⅱ provided the results of eleven reinforced concrete beams. Two
concrete beams were taken as reference. All the concrete beams were of the same mix and reinforcement. The first one was made of normal concrete while the second beam was strengthened using GFRP strip. The remained nine
beams were firstly distressed by loading them up to cracking. Then after, they were repaired using GFRP strips. The polyester contained one of three different fillers (dolomite powder, slag, or silica fume) with three different percentages (10%, 20%, and 30%). The concrete beams were tested using two points load. The load was applied as a static load. The load was monitored using a combination of load cell on the beam and digital pressure gauge. The displacement of the concrete beams was monitored using linear voltage displacement transducers (LVDT’s). All instruments were connected to a high-speed data acquisition system that made it possible to monitor the response of the tested beams through the
investigation. The results showed the enhancement of the load carrying capacity, the stiffness, the toughness, and the ductility of the repaired concrete beams due to
the use of the GFRP containing the dolomite powder. The use of the dolomite III powder as filler to the polyester resin led to ductile failure when compared with the case of using the GFRP only. The use of the dolomite powder or silica fume as filler showed relatively higher mechanical properties and better structural behavior when compared with the case of using the slag as filler. In phase Ш, a comprehensive numerical study was conducted. A new modeling procedure focusing on the actual loading condition and the multi-layer system was of the interest of this research work. For this purpose, two modeling approaches were performed and called as Model I and Model II. There is slight difference between the ultimate load and displacement values as resulted from Model I and odelⅡ.However, the results of Mode l Ⅱcould present better prediction for the beam stiffness in the elastic zone and simulated the experimental work. The numerical and experimental results were in a good agreement as the
repaired beams showed the same trend of increase in the ultimate loads
and displacements with respect to the control beam B1.