ОСОБЛИВОСТІ ВИЗНАЧЕННЯ ПРОГИНУ ЗАЛІЗОБЕТОННОГО ПЕРЕКРИТТЯ

Abstract

The features and procedure for the calculation assessment of cast-in-situ reinforced concrete floor deflection are discussed. The deflection determination method is based on the use of the
results of structures displacements computer analysis and on their correction in compliance with reinforced concrete deformation nonlinearity and load action duration. The nonlinearity of
reinforced concrete deformation is taken into account according to current norms DBN V.2.6-98: 2009 and DSTU B V.2.6-156: 2010. The deflection calculation procedure includes four main
stages as follows: 1. The analysis of forces in roof elements and of roof nodes displacements under conditionally-linear deformations.
2. The determination of the deflection short-term component with taking into account the nonlinearity of reinforced concrete deformation and crack formation. The deformation models
of structures sections are used for the correction of elements nonlinear stiffness depending on the values of moments.
3. The determination of the deflection long-term component, which is caused by concrete creep, by means of multiplying the short-term deflection value by the coefficient of concrete linear
creep. The total deflection value is the sum of short-term and long-term deflections.
4. The determination of the deflection effective values, which cause damages of the building fragile elements, by means of taking into account the intermediate values of the concrete creep
coefficient in a given sequence of loads applications. The numerical examples of deflection components calculations for reinforced concrete floors are presented. The comparison of
calculation results with the actual values of deflections in two real buildings is carried out. Based on the results of performed calculations, a number of measures are recommended for reducing the damages of building fragile structural elements supported by reinforced concrete floors.