On methods of calculation of reinforced concrete structures

Introduction . The article is debatable in nature. The authors present the results of their research, offering them for discussion and evaluation to a wide range of the engineering community: drafters of standards, developers and users of computer programs, employees of design, expert and research organizations, teachers and university students. Aim . To compare the results obtained when calculating the normal cross-sections of reinforced concrete structures using two methods: the nonlinear deformation model (NDM) and the ultimate efforts method (UEM). To analyze the implementation of NDM in various computer programs for calculations of reinforced concrete structures: OM SNiP Reinforced Concrete, Ing+, Arbat, LIRA-CAD, Lira 10, STARK ES. Materials and methods. When comparing the results obtained by NDM and UEM, bendable and non-centrally compressed elements were studied. In the case of offcenter compression, the case of a positive and negative values deformation diagram in NDM calculations is considered. Calculations were performed according to the OM SNiP Reinforced Concrete program. When analyzing the implementation of NDM in various computer programs, the algorithms provided for in SP 63.13330.2018 and used by program developers were compared, and the results obtained from the programs were analyzed. Results . Cases of significant discrepancies between the results obtained by NDM and UEM have been identified. It turned out that NDM requires significant unjustified overspending of the reinforcement installed to ensure the strength compared to UEM. The reasons for the discrepancies are indicated. The annual economic damage caused by overspending of fittings, which occurs due to incorrect calculations, is over 100 billion rubles. Accidents are also possible. Questions have been formulated for discussion in order to remedy the situation. Conclusions . The general state of calculations of reinforced concrete structures should be recognized as requiring adjustments. Discussion of the issues raised should help solve this problem. It is advisable to develop a document with a set of reference examples that allows to obtaining the same results for different programs with the same source data.