Theoretical calculation of stress-strain state characteristics and bearing capacity of normal cross-sections of combined-reinforced sfrc bending elements

Abstract

In recent years, the scope of application of reinforced concrete and combined-reinforced structures in load-bearing structures is expanding. Studies by many authors indicate the significant advantages of reinforced concrete and combined-reinforced bending elements over the classic reinforced concrete. Current state regulations do not take into account all the properties of reinforced concrete, and therefore the load-bearing capacity of structures can in many cases be underestimated. Therefore, it is advisable to take into account, when calculating, all the properties of this material.

The current state national standards for the calculation and design of fiber reinforced concrete structures are based on the fact that reinforced concrete is considered as one of the types of disperse-reinforced material. However, with this approach, many factors are taken into account, the value of which, in real conditions, can be in a wide range of values, so they are taken into account with a margin.

The article proposes an improved deformation method for calculating the stress-strain state characteristics and the bearing capacity of combined-reinforced concrete bending elements. Improved diagrams of deformation of reinforced concrete under compression and tensile obtained on the basis of experimental tests are taken into account. To evaluate the effectiveness of the method and study a number of other characteristics, two series of experimental studies of inseparable combined - reinforced reinforced concrete beams were performed. Research methods and the nature of the beams in the test process, described in [8-9]. For comparison with the obtained experimental data, the article presents the calculation of experimental beams, performed according to state standards and a simplified force method.

The proposed deformation method shows better convergence compared to the DSTU method. The average ratio of theoretical destructive bending moments to experimental is k_m = 0.98 for the proposed deformation technique, k_m = 0.843 for the method according to DSTU