Statistical description of mechanical characteristics of building structure steel

Abstract

The strength of steel is a crucial parameter of the load-bearing capacity of metal structures. Therefore, an objective assessment of the strength of steel is of great importance for ensuring and calculating the reliability of structures and the proper justification of design standards. The yield strength and other mechanical characteristics of modern steels have a statistical variance, which is well described by normal law, which has been repeatedly confirmed by test data of steel samples. The undoubted relevance of regular statistical studies of steel strength is linked to the constant revision of design standards. Factory tests of steel strength are performed for many years on a large scale, creating a significant array of statistical information. However, there is no common information database for these data. Some of them have been published in various scientific and technical journals, collections of articles, conference proceedings. Access to these publications is difficult. The translation into electronic form has taken place only for publications published after 2000. The article contains a systematic review of publications in leading scientific and technical journals on the problem of statistical description of the strength of construction steels. The main attention is paid to the selection of statistical strength characteristics of steels of different periods, such as mathematical expectation, standard deviation (standard), coefficient of variation, etc. The analysis confirmed the high security of normative and design resistances of rolling profiles made of low-carbon steel brands St3ps and St3sp. In most cases, the requirement to ensure the values ​​of the normative resistance of building materials with a probability of 0.95 for steel grade St3 is met. It is shown that the provision of the design resistances of rolled steel from St3sp and St3ps steels is always higher than the probability of 0.999. The statistical data of mechanical tests results of low-alloy construction steels 14G2, 10G2S1, 15 HSND, 10 HSND and high-strength steels are given. Thermomechanical hardened steels of high purity can be attributed to the third generation of construction steels and used in building metal structures of the most responsible and unique structures. The data presented in the article are intended for use in numerical calculations of structural reliability. In addition, the evolution of design standards for steel structures is analyzed in the sense of justification of normative and design resistances and the involvement of experimental statistics.