Analysis of reinforced concrete beams with indirect reinforcement according to limit state design

Abstract

When analyzing structures within the framework of the theory of limit state design, it is necessary to ensure sufficient reliability and safety at an acceptable level of risk. For these purposes, in engineering calculations, the mean experimental values of material strength are recalculated into design values. This article is devoted to the calculation of reinforced concrete beams with indirect reinforcement of the compressed area with transverse welded meshes for different accepted values of concrete strength (mean value of strength; design value of strength) and comparison of bearing capacity and deformations. For three series of tested beams, deformations were calculated at various stages of loading, and the bearing capacity was determined at the stage before peeling off the protective layer of concrete in the compressed area (operational stage). Calculations according to the method of the deformation model were carried out both on the basis of the mean experimental values of strength of concrete and reinforcement, and on the basis of the design values. It was found that in calculations based on the design values of the material strength, the ultimate deflections in some cases exceed the values obtained on the basis of the experimental mean strength values, which should not be. In this regard, it was indicated the need to calculate the parametric points of the design stress-strain diagram of concrete with indirect reinforcement according to the experimental mean strength values and only after that take into account the necessary reliability coefficients and obtain the final design values.