3, Injection method: when crack width of smaller and more deeply, it can be used to repair material injection concrete repair methods within the first one-person crack injection tube, other parts with surface treatment method, using low-viscosity epoxy resin injection material, using an electric pump or pump into the patch, this method to the crack width is greater than 0.2mm, the better.
(B) If the beam cracks affect the bearing capacity of beam, they should be more careful study, analysis and comparison, using cost-effective methods, to reinforcing purposes, methods that can be used are:
 1, Steel hoop reinforcement method: this method is suitable for effect of bandits in the long stirrup and insufficient bending reinforced, shear does not meet requirements of. Specific method is: made with flat or round steel vertical or oblique steel ring ends have a threaded, nest the plate with nuts after tightening. May also be used by the two u-shaped steel clamp after welding, and then break into the metal wedge wedge. The steel ring grooves to prevent slipping on the beam when.
2, Paste method: steel plate or steel reinforced with modified epoxy resin adhesive, bonding to the component parts of concrete crack surfaces, steel (or steel) and concrete into the overall work together. Before bond, sand blasting steel surface, brush the dried on surface of concrete, bonding layer thickness is about 3mm.
3, Beam three or four plus enclosed-law: lack of strength or stiffness, shear beam and large case difference, using beams of three or four more reinforcement of reinforced concrete encircling more appropriate. Enclosed on four sides wall thickness should be according to the actual situation may be, generally on both sides is greater than 50mm, upper and lower than 100mm, longitudinal reinforcement and stirrup determined by calculation. When the beam floor limit, can be enclosed on three sides, thickness of concrete on both sides at this time should be greater than 100mm, vertical reinforced φ 25 available with the original beam longitudinal reinforcement welding, the construction of both sides of the beam interval 500mm in-situ reinforced concrete by digging holes on the plate, hoop hoop available openings closed or wear plate collar, and calculate to determine quantity of reinforcement.
4, Beam with increasing section method on one side: one side with increasing section method is pided into two kinds, thickened height above or below. Beam height above the applicable bearing insufficient bending strength and reinforcement of Yu Liang, plus concrete welding on the original beam attached on the upper Stirrup Stirrup with original concrete to form a whole, top loading by additional longitudinal reinforcement to bear. Beam thickened below applies to insufficient flexural reinforcement in beam, when the beam intensity and at more or less the required, thicken under the beam can be 80-100mm, the preparation of new longitudinal reinforcement and the original steel welded, practices with the enclosed on three sides. When the lower part of the section of a beam increases over 100mm, by computing configuration of longitudinal reinforcement and stirrup. When reinforced by use of Wai and thickening on one side, longitudinal reinforcement and support connection has the following methods: beam supported on columns when the new longitudinal reinforcement and column force directly through the connection plate or reinforcement welded together; when main girders of girder supporting in, in the last set of main girder inclined support.
7.     Building Codes
The American railway engineering Association appointed a Committee on masonry in 1890. In 1903 this committee presented specification for Portland cement concrete. Between 1908 and 1910 a series of committee reports led to the standard building regulations for the USA of reinforced concrete published in 1910 by the national association of cement users which subsequently become the American concrete institute.
A joint committee on concrete and reinforced concrete was established in 1904 by the American society of civil engineers, American society for testing and materials, the American railway engineering association, and the association of American Portland cement manufactures. This group was later joint by the American concrete institute. Between 1904 and 1910 the joint committee carried out research. A preliminary report issued in 1913 lists the more important papers and books on reinforced concrete published between 1890and 1911. The final report of this committee was published in 1916. The history of reinforced concrete building codes in the United States was reviewed in 1954 by Kerekes and Reid. 钢筋混凝土英文文献和中文翻译对照(6):http://www.youerw.com/fanyi/lunwen_4679.html