Influence of intramodular joints stiffness to the stress-strain behavior of modular buildings constructions

Introduction. The steel structure joints stiffness significantly affects the distribution of internal forces in the frame elements. This point is true for modular buildings too. Intermodular joints affect the stress-strain behavior of the whole building, while the intramodular joints stiffness of affects the stress-strain behavior of each module individually. The object of the research is steel modular buildings made of assembled modules with load-bearing corner columns.

Aim. Studying the stress-strain behavior of steel modular buildings with rigid and semi-rigid intra-modular joints exposed various loads.

Materials and methods. To assess the influence of the joints stiffness to the stress-strain behavior of modular buildings, a series of studies were conducted with various connection parameters using the finite element method. A total of 921 joints models were calculated. To confirm the results obtained by the numerical method, physical tests of full-size specimens of the joints were carried out. The main assumptions for the creating of calculation model have been formulated. Based on the identified assumptions, equations were obtained that explicitly describe the influence of the rotational stiffness of intra-modular joints to the distribution of internal forces in the elements of the module and to the natural vibration frequencies of the building.

Results. Within the framework of numerical studies using the finite element method, a significant influence of the presence of stiffeners and their dimensions on the intra-modular joints stiffness was established. It is shown that nodes without stiffeners are generally semi-rigid. For the design of rigid intra-modular joints, nomograms have been compiled for the assignment of minimum stiffeners sizes. Physical tests of full-size joints specimens confirmed the results obtained in numerical studies. A calculation analysis using the obtained equations showed that failure to take into account the actual joint stiffness o when calculating the rod model of a modular building can lead to significant inaccuracies in determining the internal forces and frequencies of natural vibration.

Conclusion. The conducted researches show a significant influence of intra-modular joints stiffness to the stress-strain behavior of steel modular buildings. It is necessary to take into account the joints stiffness when calculating modular buildings. It is of interest to conduct similar studies for other structural schemes of modular buildings with different structural solutions of joints.

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