Calculation of Reinforced Concrete Frames for a Special Design Situation with Discrete Crack Modeling

The methodology of calculation of reinforced concrete frames of buildings for a special design situation caused by initial local failures, taking into account the violation of the continuity of the concrete matrix during crack formation, is proposed. The verification of the proposed methodology is carried out by comparing it with the results of experimental data for a U-shaped reinforced concrete frame with prestressing. The bending moments in the frame, determined by the proposed calculation method, are in practically complete agreement with the values found experimentally. As a result of cracking, there was a redistribution of bending moments in the beam of the frame: the moments in the structural nodes decreased by 148 % and increased in the span by 37.5 % compared to the results obtained using the traditional finite element method approach. On the basis of the results of the calculation of the reinforced concrete 3-storey frame by the proposed method, the increase of longitudinal tensile forces in the beam support sections above the zone of local failure at failure of the middle row column is revealed in comparison with the traditional approach to modeling. The revealed effect may lead to an increase in the influence of longitudinal bending for the outermost row column to which the beam is adjacent.