Issues of calculating steel-reinforced concrete beams are considered taking into account a nonlinear concrete diagram based on the Sargin formula. The nonlinear system of equations for determination of curvature and neutral axis, which is solved numerically, is written in explicit form. Explicit expressions for determination of other calculated quantities needed for design of steel-reinforced concrete beams are derived. Numerical examples are given. The analysis of accounting nonlinearity in comparison with the linear calculation is carried out.
The deflection of a steel concrete beam at an operation stage sharply increases in case of formation of a normal crack in the stretched zone of concrete and can lead to violation of its normal operation, and in certain cases warns about possible accident. In article the method of measurement and monitoring of a deflection of a beam, a method of calculation of reliability of a beam by criterion of a deflection is considered in case of limited statistical information on values of a deflection in timepoint of t, determination of a residual temporary resource of a beam by criterion of a deflection in case of the known extreme (standard) value of a deflection of a beam.
Currently, there are many software systems and environments that allow you to simulate and perform fairly complex and voluminous calculations associated with dynamic effects on structural elements of overpasses. The aim of the article is to make an analysis of a reinforced concrete railway overpass as a whole and its elements separately. The article presents the calculated and experimental data of the forms and frequencies of natural vibrations of reinforced concrete railway overpasses under constant loads and the rolling stock off the span. As a result of the analysis of the tests, it was determined that the effect of the rolling stock passing through the reinforced concrete beam spans of 16.5 m and 23.6 m appears with frequency perturbations that are in the range f = 4.41 ÷ 9.52 Hz. These studies can be further used in the design of artificial structures, as well as to identify defects in structural elements of railway bridges.
Calculation of steel-reinforced concrete beam for instant loading taking into account the non-linearity of the concrete diagram ε-σ
