Feature of Calculation and Design near Support Regions of Prestressed Concrete Beams with Flat Bent-Up of Longitudinal Reinforcement

ABSTRACT

The developed model of calculation of shear resistance of prestressed concrete beam-type elements with flat bent-up longitudinal reinforcement, based on the rules and assumptions of the modified compression field theory and general shear design method, is presented in the article. The main feature of the advanced model of shear resistance is the account of a direction and magnitude of principal stresses from the effect of prestress force by the bent-up reinforcement, the valid angle of rotation of the principal cross-sections from the effect of external forces and an inclined compression strut at a joint action of all internal forces for prestressed concrete beamtype elements in biaxial stress. It consists in the fact that at the initial state, before the application of external loading the principal compressive strains in prestressed concrete beams are inclined to the point of the application of prestress force by the bent-up reinforcement, and under the effect of external force there is rotation of the principal strains in the opposite direction. As a result at the stage before failure the angle of inclination of the principal compressive strains to a longitudinal axis is flatter than at a straight arrangement of prestressed reinforcement.

Constructive provisions that provide shear resistance of prestressed concrete beam-type elements with flat bend of a part of longitudinal strands to effect of bending moments and shear forces are introduced. The results of the statistical analysis of the offered model in comparison with the design model of inclined cross-sections (a method of limiting force) and the empirical one based on the truss model.

Keywords: model, reinforced concrete constructions, stresses, shear, reinforcement, strains, critical sections

For citation: Malinovskiy V., Krivitskiy P. Feature of Calculation and Design near Support Regions of Prestressed Concrete Beams with Flat Bent-Up of Longitudinal Reinforcement. Contemporary Issues of Concrete and Reinforced Concrete: Collected Research Papers. Minsk. Institute BelNIIS. Vol. 7. 2015. pp. 78-89.

Full text in Russian: 

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