Influence of Flexibility of Bolted Joints on Rigity of the Hingeless Frame

Abstract

The article investigates the influence of the flexibility of the rigid node of connection of the crossbar with the frame rack on the stress-strain state of the elements under the action of vertical evenly distributed load on the crossbar and horizontal evenly distributed load, applied to the frame racks. Since the bolts in the flange connection are stretched by the action of the bending moment, the nodes open, that is become partially hinged. Knowing some initial parameters of ideally rigid knots, it is possible to establish, what influence their change will have, both on the design scheme of a frame as a whole, and on its separate elements. The initial parameter method was used to determine the influence of the flange opening angles on the stress state of the elements. The proposed method allows us to determine the rigidity of any bolted flange connection, taking into account its actual operation. Taking into account the pliability of the nodes and, as a consequence, the structure as a whole, allows us to unload the elements and calculate the additional resource bearing capacity. In addition, the technique allows you to adjust the stiffness of the bolted joint by changing the diameter of the bolts, their number, distance between them or changing the thickness and height of the flanges, as well as use additional material resource by reducing the maximum stresses in the calculated cross sections.