The Experimental Study Of The Carbon Fiber Strengthening Reinforced Concrete Beams And Slabs' Bending Properties

Sticking carbon fiber (Carbon Fiber Reinforced Polymer, briefly called CFRP) is a new method of strengthening reinforced concrete structure. Because of its many advantages and high performance, great concern and interest has been aroused in the civil engineering both at home and abroad. But the carbon fiber strips destruction is a common problem in this reinforcement method, overcoming this kind destruction has become the most important topic in applicating the carbon fiber widely.In order to study the enhancement on the bearing capacity of the bending beam and the plate with the carbon fiber, the influence caused by the different carbon fiber adhesive area, especially the influence of the X-band and the U-band to the anchor effect respectively, the article studies and analysis the flexural Strengthening Reinforced Concrete Beam & Plate with externally carbon fiber both experimentally and theoretically .The experiment has been carried on with 5 hollow cast-before-situ and pre-stressed concrete plates with the same size and the same rate of steel and 11 simple rectangular cross-section beams with the same size, the same steel rate except that 3 ones with only 1 layer of the carbon fiber. During the experiment, different layers of carbon fiber has been fixed to these structures, the strengthening effect of the U-Anchorage, X Anchorage and non-Anchorage has been compared with, the beam deflection in the center, cracking load and the distortion and strain of the steel, carbon fiber have been taken the record of as well, the destruction and the cracking development situation have been observed, too.The result shows that: strengthened with the carbon fiber, the bearing capacity in the cross-section of reinforced concrete beams and slabs has been greatly improved.Affections of the carbon fiber layers are the most obvious and tremendous of all, the more, the better. However, this growth is not linear. With the carbon fiber, they cracks slightly late, and the more the layer, the later the crack develops and the smaller the crack width and spacing. Compared to U-Anchorage and non-Anchorage, X Anchorage is much better. Besides, the stiffness has increased in a certain degree, especially those with more CFRP-adhesive layers.The article describes several methods of calculating the supporting capacity of the carbon fiber strengthening reinforced concrete beams theoretically, compares with the calculating methods and codes of the carbon fiber strengthening in the USA, points out the shortcoming and insufficiency in China, and elaborates the stress condition and the strips mechanism when the destruction happens and so on.