Collisions of Strength Determination Modeling for Eccentrically Compressed Reinforced Concrete Constructions with Small Eccentricities by Normal Sections in Lira-FEM Software

It is implemented the strength calculation method for normal rectangular cross-sections of shell reinforced concrete elements with flat eccentric compressive strength using the nonlinear deformation model. The main calculation results are analyzed for the case of small eccentricities compression with varying next parameters: concrete classes, the height of the cross section and the reinforcement coefficient. There are investigated the dependence diagrams “bearing capacity Nint – eccentricity of longitudinal force ered” at gradual change of cross-section stress-strain state from eccentric to the nominal central compression. Two typical calculation cases in which calculation collisions occur are investigated. The bearing capacity of the section decreases in proportion to the decrease in the value of external forces eccentricity in the zone of small eccentricities in the first case. It is not possible to determine the bearing capacity in the second case. An alternative technique is to move to the strength determination area, based on the method of ultimate forces. This technique has acceptable accuracy and high speed of calculation. The proposed method is implemented in the “LIRA-FEM” software by a new algorithm for calculating reinforced concrete plate (shell) elements “Wood +”.