Bending deflection reinforced concrete elements determination

Dmitriy Kochkarev,Taliat Azizov,Tatyana Galinska,G Vatulia,A Plugin,O Darenskyi

doi:10.1051/matecconf/201823002012

Abstract

Longitudinal reinforced concrete elements stiffness exhaustion, often used in building practice, precedes obtaining bearing capacity, and therefore deflections determination becomes a determining factor in their design. In connection with it precise methods for determining such reinforced concrete elements deflections become especially relevant. The elastic-plastic properties of concrete and cracks in the stretched zone of reinforced concrete elements lead to a significant change in their bending stiffness. That is why the deflections determined by the materials classical resistance formulas differ significantly from the real ones. A large quantity of methods for determining deflections is based on the elastic characteristics correction of reinforced concrete elements consolidated section. Such methods, although providing calculation satisfactory results, are rather approximate and have empirical nature, due to it they have limited application. More precise calculation methods consist of curvature usage to determine deflections. The curvature of reinforced concrete elements cross sections is determined directly from the equilibrium equations, which are written taking into account nonlinear materials deformation diagrams. Calculation examples for bending reinforced concrete elements deflection are given.

Highlights

More precise calculation methods are in curvature usage to determine deflections
Reinforced concrete elements cross sections curvature is determined directly from the equilibrium equations, which are written taking into account nonlinear materials deformation diagrams or piecewise linear diagrams [8, 9]
The simplified and precise methods of deflection bending reinforced concrete elements determination according to curvature are offered

Summary

Review of recent studies and publications

Bending deflection reinforced concrete elements determination is a very topical task, when designing large spans reinforced concrete elements. A large number of methods for determining deflections are based on the correction of elastic characteristics of reinforced concrete elements consolidated sections [1, 2]. More precise calculation methods are in curvature usage to determine deflections. Reinforced concrete elements cross sections curvature is determined directly from the equilibrium equations, which are written taking into account nonlinear materials deformation diagrams or piecewise linear diagrams [8, 9]. There are methods where a reinforced concrete beam is considered as a composite rod [10] These methods are sufficiently precise, but not convenient in the complex repeatedly statically uncertain systems calculation. Let's show curvature changes schedule in the bending reinforced concrete elements sections (Fig. 1). A more precise method for calculating deflections is to consider separate cross sections with cracks and between cracks, which allows getting a complete picture of a cracked formation. For most engineering calculations it is quite enough to use methods using the averaged section, which are proposed to be considered

Basic material and results

Examples of application of the proposed calculation method

Conclusions