الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 212 |  |  |
| | | from | 212 | | |
Abstract
For corrosive environments, The GFRP profiles are the ideal choice instead of traditional materials such as steel. Replacing GFRP profiles instead of steel profiles could be considered as an effective solution in areas that are subjected to chemical and bad weather conditions, because they can withstand corrosion. GFRP material weighs 75% less than steel and 30% less than aluminum. For electric conductivity, GFRP material is considered nonconductor for electricity. GFRP material is good insulator with low thermal conductivity coefficient which equal from 0.2 to 0.58 in watts per meter-kelvin (W/(m·K)) whereas the thermal conductivity coefficient ranges from 50 to 70 in steel. The thermal conductivity is the property of a material to conduct heat. Heat transfer occurs at a lower rate across materials of low thermal conductivity than across materials of high thermal conductivity. Also, the costs of installation GFRP profile is lower than steel. GFRP profiles can be field-fabricated using simple carpenter’s tools with carbon or diamond tip blades. There is no need to torches or welding required. Light weight allows easier transport and installation. Finally, pultruded GFRP profile is less maintenance than steel and life longer which reduce the life cycle cost. Choice of GFRP to act with concrete as a composite material depends on recommendations mentioned in ACI318. ACI318 states that the strength of composite sections depends on the compatibility of two materials (concrete and reinforcing material). To prevent the discontinuity or separation of the two materials under load, the reinforcing material has to undergo the same strain or deformation as the surrounding concrete. Also ACI 318 recommends that the rupture strength of the reinforcing material must be higher than the rupture strength of concrete. Steel and FRP material can provide this requirement. A new composite column composed of glass fiber reinforced polymer GFRP profiles, concrete and reinforcing steel is studied in this research to represent a composite column can construct at corrosive environment, weight less and less conductivity for heat and electricity. So, existence of steel reinforcement is unwanted in this proposed section but the author cannot be able to replace the steel reinforcement with FRP bars because of the provision stated in Egyptian code of practice for the use of fiber reinforced polymer (FRP) in the construction fields which mentioned that FRP bars are primarily used to resist tensile stresses and it shall not be used to resist axial compression. Also, the previous code stated that the FRP bars could be extended in the compression zone to develop the bond length of the bar. The author recommended confining the composite column with FRP strips instead of reinforcement bars. Up to the author knowledge, little studies conducted on composite column consisting of GFRP encased in concrete are found in the literature. Experimental investigations are conducted to determine the behavior, the ultimate compressive capacity and the mode of failure of the composite columns consisting of GFRP profiles encased in concrete. The experiments include tension and compression tests as well as full scale tests for specimens having various lengths. The tension test is performed according to ASTM D 5083 to determine the tensile properties of pultruded GFRP material. The axial compression test is performed on cylindrical specimen according to ASTM D695 and also on stub column to obtain the compressive behavior of the GFRP material. A full scale column is tested under compressive load in a vertical position for columns consisting from Pultruded Fiberglass GFRP profile encased in concrete columns. Experimental tests are performed by applying concentric load on GFRP Profiles encased in concrete columns to study their behavior. A nonlinear pin ended 3D numerical models are developed in this study using the commercial program ABACUS to simulate the behavior of pultruded GFRP profiles encased in concrete column under concentric compression load. The initial geometric imperfection of the column is included in the model. The inelastic behavior of concrete is represented using Hognestad in compression and Nayal and Rasheed in tension. Also, the effect of concrete confinement is considered in the model. An eight node zero thickness interface element is used to simulate the interaction between the concrete surface and pultruded GFRP profile surface as the two surfaces cannot penetrate each other. The results obtained from numerical model are compared with the results recorded from tests. Based on the experimental and numerical results, the study proposes a design method to obtain the compressive strength of the composite columns consisting of GFRP encased in concrete and subjected to axial compression load.