STRENGTH ANALYSIS OF BIAXIAL BENDED REINFORCED CONCRETE T-SECTION ELEMENTS BY SIMPLIFICATED DEFORMATION MODEL

Abstract

Reinforced concrete T-shape and I-shape profiles are widely used in the design of various buildings, in particular in residential, civil, industrial and special engineering. Taking into account the phenomenon of biaxial bending when calculating the strength of all bending elements is hampered by the absence of simple and sufficiently precise engineering techniques for calculating the strength of biaxial bended elements corresponding to the requirements of the current normative documents on the design of reinforced concrete structures. In relation to the T-section, the problem is further complicated by the variety of geometric shapes that can be acquired by the compressed area of the section in the case of biaxial bending. Thus, obtaining analytical calculation dependences for each of the forms of the compressed area of concrete will allow to develop a general methodology for calculating the strength of biaxial bended elements, which will include calculation for simpler profiles, in particular, rectangular.

The method of calculating the bearing capacity in the normal section of biaxial bended reinforced concrete T-section elements is developed. The problem of difficulty applying the deformation model in the study of biaxial deformed elements is successfully solved by the introduction of the rectangular stress distribution in a concrete compressed area and deformative criterion of strength. Analytical formulas are derived for the determination of all unknown parameters when calculating for biaxial bending: the neutral axis depth, the angle of inclination of the neutral axis, and the internal bending moment. The method is proposed for calculating beams with a trapezoidal shape of the concrete compressed area, taking into account all provisions of the effective normative documents and, unlike the existing ones, allows performing calculations without the use of numerical methods. The developed method of calculating provides the necessary accuracy of the calculations and can be implemented in the form of an engineering algorithm.