Deformability and Strength Determining of Coupling Fittings of Steel Reinforcement in the Reinforced Concrete Structures

The fittings on the thread which replace the traditional lap connection begin to find more and more application in reinforcing of modern reinforced concrete structure.The valuation techniques of deformability and strength of coupling fittings of reinforcementon the thread which are increasingly used in construction is presented. The method is based on the comparison of stress-strain diagram of one-piece reinforcing bar with the stress-strain diagram of the connecting rod in the place of installation fitting.On the basis of experimental studies of stress-strain diagrams of one-piece reinforcing bar and butt joints of its rods it was found that the joints of reinforcing bar are more deformation. By comparing of the strain of butt joint with the same of one-piece reinforcing bar corresponding to the calculated deformations of the reinforcement ɛs and ɛs0.2 there are determined the coefficients of the reduction factors of these deformations γs in the butt joints which used at designing of reinforced concrete structures.