The article is devoted to the analysis of calculation and design problems and features that arise when designing multi-storey modular buildings with a steel frame. The article describes the main features of the classification and trends in the construction of volumetric block buildings in Russia and the world.

The object of the study is quick-assembly connections of compressed-bent load-bearing elements of frame modular systems.

The main purpose of the study is to obtain reliable analytical and theoretical data to determine the characteristics of the rotational stiffness of module connection nodes and assess its influence on the stress-strain state of the frame and its elements.

Within the work, the concept of an experimental modular building was developed using I-beam columns as part of the frame, as well as inter-module joints for their connection. Flange connections with high-strength bolts without controlled tightening are considered as the main design solution for the inter-module connections. The designed connections include inspection windows to access the hardware.

A numerical study was performed to evaluate the bearing capacity and stiffness of the connections. The influence of the stiffness on the behavior of the frame in relation to two groups of limit states was assessed using the finite element method.

The paper substantiates the relevance of using I-beam profiles as columns of the frame of a modular building, which is not a common solution in modern practice.

The developed concept of quick-assembly inter-module flange connections makes it possible to ensure the safety of the building while reducing the time and labor costs for its installation.