Experimental Study On Durability Of GFRP Pipe Confined Concrete Columns Under Dry-wet Circulation And Immersion

Because of durability problems, reinforced concrete structure is not suitable in the corrosive environments, but the fiber-reinforced composites(FRP) for its corrosion-resistant, high-performance and other advantages, has been widely used in the field of civil engineering. Many scholars have studied the mechanical properties and durability of FRP confined concrete structures, but for durability, it is mainly focused on the FRP cloth strengthened concrete structures, and few focused on the FRP pipe confined concrete structures. In this paper, through laboratory accelerated tests are adopted, while the environments are simulated by wet and dry cycle, completely soaked, respectively. Therefore, an experimental study on GFRP pipe confined concrete columns under the different corrosive environments and corrosion cycles are carried out to investigate the durability and load capacity of GFRP pipe confined concrete columns. Specific experiments and research achievements include the following aspects:(1) The water solution(including water and sea water) on the erosion mechanism of concrete and FRP materials are analyzed, respectively, and dry-wet circulation is relatively more serious than complete immersion corrosion.(2) The durability of GFRP pipe confined concrete columns under the water dry-wet circulation, seawater dry-wet circulation, water immersion and seawater immersion environments with different corrosion cycles are investigated by tests, respectively, including the failure characteristics, ultimate bearing capacity, stress-strain curves and deformation capacity of composite columns. The research shows that the corrosion has influence on the GFRP pipe confined concrete columns, and the strength, stiffness and ductility of those columns have different degree of reduction.(3) Using the experimental data to assess the existing strength model, Toutanji model is in good agreement with this article. Considering the influence of environmental factors and based on the Toutanji model, strength model is derived which is suitable for corrosive environments, it can be referenced by the actual. Ultimate axial strains are validated with using Lam and Teng model, the impact of environmental factors and the wrapping angle are recommended to consider.