Curvilinear Stress-Strain Relationship for Concrete of EN-2 Regulation in the ZI Method and the Calculation of Beam Strength

The article illustrates the possibilities of the practical application of the ZI method [1 and 2] when calculating the strength of reinforced concrete beams. The article presents variants of description of the EN-2 regulation curvilinear diagram for concrete [[sigma].sub.c] - [[epsilon].sub.c] with reliability of 50 % by the ZI method with reliability of 50 %, 95 % and ~100 %. The article demonstrates how, when calculating the strength of normally and abundantly reinforced concrete beams by the ZI method, it is possible to do without the calculation of the limit value of the thickness of the concrete layer of the beam compression zone. This is important in the case of the calculation of the strength of abundantly reinforced beams. The method for calculating the strength of abundantly reinforced beams has been improved. When calculating strength, we also obtain actual values of stress-strain parameters at the crack. The tables provide data supporting the proposed innovations and facilitating calculations.