Cfrp Strengthened Reinforced Concrete Beam Temperature Field Of Fire At High Temperatures

Researches on the technology of CFRP (carber fiber-reinforced polymer) strengthening concrete structures are in high-speed development in China, and the application of CFRP strengthening structures such as buldings, bridges etc. is widely used. Although there are many advantages of CFRP used for structural strengthening, there are some shortcomings as well as not being able to bear the high temperature and fire. There are few researches about fire protection design of CFRP strengthening concrete structures in foregin countries, and seldom in China. The finite element simulation analysis of reinforced concrete beam damaged in fire and strengthened with CFRP was presented in this paper, and the numerial Calculation for temperature field of reinforced concrete beam strengthened with CFRP in fire was conducted too.(1) The ANSYS8.0 was used to analyze the performance of reinforced concrete beam damaged in fire and strengthened with CFRP. The calculation results had good coherence to experimental data, and showed that the finite element method for calculating the nonlinear composite is a effective one, and could meet the needs of engineering.(2) The rules of thermal parameter and mechanical property of concrete, steel bar and CFRP at elevated temperature were compared in domestic and foreign countries', then selected properly parameters to analysis the temperature field of reinforced concrete beam strengthened with CFRP.(3) The module of transient thermal analysis was used to calculate the distribution of the temperature filed of reinforced concrete beam strengthened with CFRP in fire in different conditions that having fire retardant coatings or not and in different smearing forms of fire retardant coatings. The results showed that the thermal performances of CFRP had few effects to the temperature filed of beam, and temperature filed of beam strengthened with CFRP were consistent with the unstrengthened, and the curve shape of relationship between temperature and time of the surface of CFRP was basically in accordance with ISO-834 if there having no fire retardant coatings, and the CFRP reached the fire-resistent limit and lost strengthening effect quickly, so there was almost no heat-resisting ability of CFRP; The temperature of the surface of CFRP decreased significantly if there having fire retardant coatings, and the fire-resistent limit of the common epoxy resin could get 1.5h, and 2.5h of the high temperature resistant epoxy resin if the fire retardant coatings got the depth of 40mm, and the form of smearing the fire retardant coatings all-arround the bottom surface and the two sides of the beam had the best effect of fire prevention.The relevant analysis and research results about the fire-resistance capability of reinforced concrete beam strengthened with CFRP possess certain practical theoretically and engineering to the fire proof design.