STRENGTHENING OF RC SHORT COLUMNS WITH EXTERNAL CARBON FIBER POLYMERS
Mahmoud El.Sayed Mahmoud Mohammed Abo El.Kheir;
Abstract
Strengthening of reinforced concrete columns with carbon fiber reinforced polymer (CFRP) is one of the most used strengthening techniques recently. It offers an attractive solution to enhance capacities of RC columns.
This research investigates the behavior of strengthen normal reinforced concrete short columns using external FRP jacket. The main parameters are: load eccentricity (e/t), cross section aspect ratio, radius of corner and cross section, retrofit reinforced concrete columns partially. Twelve models with dimensions 250 × 250 × 3000 mm and round corners with radius 25 mm are used. Three different eccentricities 0, 25, 50, and 75 mm are investigated with e/t ratio equal 0, 0.1, 0.2 and 0.3. In relation to the number of FRP layers, unwrapped columns, columns wrapped with two layers, and columns wrapped with three layers are studied. The four corners of the specimens were rounded for the purpose of avoiding premature failure, and to prepare sufficient effect of confinement of the columns.
There is a sharp decline in the axial deflection value as long as the value of eccentricity is increased. There is a significant increase in the value of lateral deflection while the value of eccentricity is increased. While for the wrapped models, an increase in the axial and lateral deflection are noticeable as long as the number of FRP is increased.
Six models with six different cross section aspect ratio are chosen which are 1.0, 1.2, 1.4, 1.6, 1.8 and 2.0 with a constant height equals 3000 mm and round corners with radius 25 mm. Concrete compressive strength is 40 MPa for all models,. Finite element models were tested under axial load and, it can concluded that confinement by FRP jackets enhances the performance of concrete columns. However, CFRP wrapping is more effective for square sections than for rectangular sections so columns with a larger aspect ratio requires a thicker FRP jacket to avoid strength degradation before the FRP ruptures. Twelve models with four different radius of corner are chosen 5, 10, 15, 20 mm with a constant height equals 3000 mm. with aspect ratio, (t/b), and r is the corner radius. The failure of the FRP jacket in confined sections occurs at or near the corners of the sections. Furthermore, FRP confining mechanism has the full efficiency at the corners while this efficiency reduced outside this region. While increasing corner radius in models with certain cross section increases strain concentration at corners. The analysis of results proved that the general behavior of the FE models shows a good agreement with corresponding theoretical models results.
This research investigates the behavior of strengthen normal reinforced concrete short columns using external FRP jacket. The main parameters are: load eccentricity (e/t), cross section aspect ratio, radius of corner and cross section, retrofit reinforced concrete columns partially. Twelve models with dimensions 250 × 250 × 3000 mm and round corners with radius 25 mm are used. Three different eccentricities 0, 25, 50, and 75 mm are investigated with e/t ratio equal 0, 0.1, 0.2 and 0.3. In relation to the number of FRP layers, unwrapped columns, columns wrapped with two layers, and columns wrapped with three layers are studied. The four corners of the specimens were rounded for the purpose of avoiding premature failure, and to prepare sufficient effect of confinement of the columns.
There is a sharp decline in the axial deflection value as long as the value of eccentricity is increased. There is a significant increase in the value of lateral deflection while the value of eccentricity is increased. While for the wrapped models, an increase in the axial and lateral deflection are noticeable as long as the number of FRP is increased.
Six models with six different cross section aspect ratio are chosen which are 1.0, 1.2, 1.4, 1.6, 1.8 and 2.0 with a constant height equals 3000 mm and round corners with radius 25 mm. Concrete compressive strength is 40 MPa for all models,. Finite element models were tested under axial load and, it can concluded that confinement by FRP jackets enhances the performance of concrete columns. However, CFRP wrapping is more effective for square sections than for rectangular sections so columns with a larger aspect ratio requires a thicker FRP jacket to avoid strength degradation before the FRP ruptures. Twelve models with four different radius of corner are chosen 5, 10, 15, 20 mm with a constant height equals 3000 mm. with aspect ratio, (t/b), and r is the corner radius. The failure of the FRP jacket in confined sections occurs at or near the corners of the sections. Furthermore, FRP confining mechanism has the full efficiency at the corners while this efficiency reduced outside this region. While increasing corner radius in models with certain cross section increases strain concentration at corners. The analysis of results proved that the general behavior of the FE models shows a good agreement with corresponding theoretical models results.
Other data
| Title | STRENGTHENING OF RC SHORT COLUMNS WITH EXTERNAL CARBON FIBER POLYMERS | Other Titles | تدعيم الأعمدة الخرسانية المقواة خارجيا بالكربون فايبر | Authors | Mahmoud El.Sayed Mahmoud Mohammed Abo El.Kheir | Issue Date | 2020 |
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