Research into the stiffness of beam-column joints of modular prefabricated buildings

Introduction. Rotational stiffness of a joint in modular building frames is the subject of this research. The stiffness of joints has a direct impact on the analysis of building structures. However, Russian design standards lack any clear instructions concerning this characteristic. Modular buildings have non-standard joints; therefore, it is necessary to study their rotational stiffness. The purpose of this work is to differentiate rigid joints, connecting a channel beam to a square pipe column, from semi-rigid ones. Materials and methods. Joints are classified according to Eurocode 3, that sets the limits for pinned, rigid and semi-rigid joints. The component-based finite element model implemented in the IDEA StatiCA software package is used to calculate the value of initial rotational stiffness. Two types of joints were studied: one that has an angle stiffener, and the other that has none. Results. The values of rotational stiffness of beam-column joints are obtained. It’s been identified that the joints of spans, typical for modular buildings, having no angle stiffeners, should be classified as semi-rigid and their rotational stiffness should be taken into account in designs. The variability of rotational stiffness of joints, having angle stiffeners, is nonlinear. If the dimensions of an angle stiffener are close to those of the cross section of a column, rotational stiffness rises steeply and joints turn rigid. Conclusions. A nomogram was made for various sections of channels and pipes having minimum angle stiffener dimensions, ensuring the rigidity of beam-column joints. The nomogram is recommended as a guidance for setting angle stiffener dimensions. Acknowledgements. The co-authors would like to express gratitude to the editorial staff for the fast preparation of this article for publication. The co-authors are also grateful to the reviewer for his constructive feedback that has enabled them to improve the text of the article.