The theoretical and practical aspects of assessing the fire resistance limit of load-bearing building structures occupy a very important place in the system of building fire safety analysis. The fire resistance limit is a key parameter that determines the ability of structures to maintain strength and stability under high-temperature fire conditions. Modern approaches, including experimental and computational methods, as well as numerical modeling methods used in engineering practice, are considered. A comparative analysis of Russian and international regulatory documents regulating fire resistance assessment methods is presented. The factors influencing the accuracy and reliability of the assessment are considered: properties of materials, features of temperature exposure, geometric parameters of structures, types of loads. Special attention is paid to the use of software systems to simulate the thermal and mechanical behavior of structures in a fire. The necessity of an integrated approach to the assessment of fire resistance, combining computational and experimental methods, is substantiated. The findings can be used in the design of public buildings and the development of measures to ensure their fire safety.