Theory of structures and design codes

Building structures should correspond to the reliability requirements which are implemented with the help of design codes. The latter are based on the method of limit states. In order to simplify the verifications, the design codes often deliberately deviate from the scientifically based theoretical provisions of such fundamental disciplines as the theory of elasticity and the theory of plasticity, replacing them with the so-called working practices. The paper presents that there are inaccurately formulated recommendations in the design codes. The paper also specifies on some important problems that are not reflected in the design codes. This applies to the choice of failure probability values, the use of partial reliability factors, the calculation methodology in case of an emergency, the problems of using the results of nonlinear calculation, etc. The paper presents some considerations on these issues, with the main attention being paid to the analysis of the existing design tradition and guidance to unresolved issues. The problems of recommended reliability parameters, clarification of the limit state concepts, analysis of accidental situations, the safety factors values and possible relationship between the safety factors for load and the safety factors for materials, loads and load effects, vulnerability assessment as well as reliability of protected systems have been considered. The considerations presented by the paper give only a partial idea of the range of issues that arise when comparing working practices used in the design codes with the theoretical fundamentals they should correspond to. It should also be noted that the design codes do not provide any justifications for their recommendations. The presented paper can initiate a scientific discussion and be useful both for the developers of design codes and for the developers of software packages implemented the design codes.