Determination of rigidness of node bolt joints

Abstract

In the current domestic and European design standards for steel structures, the boundary conditions of bolted and welded joints are idealized, i.e. they are rigid, articulated, etc., which does not fully meet the actual conditions of their work and that of structures in general. This is especially true for bolted flange and anchor joints of columns of industrial building frames, which, in idealized calculated schemes, are considered rigid, as well as crossbars, which rest on certain supports (beams, columns, etc.) and fastened to them with mounting bolts. In calculations using an idealized calculated scheme, such a connection is considered hinged, and the bolts perform only the functions of the beam retainer in the design position. In fact, under the action of external loads, the rigid nodes open, i.e. partially become hinged. The hinged nodes of freely supported span elements undergo deformations due to the deflection of these elements. As a result, the bolts are stretched and interfere with free deformation on the supports, i.e. these supports become partially rigid, which affects the redistribution of forces along the entire length of elements.The purpose of the studies is the theoretical determination of the actual stiffness of bolted rigid and hinged joints of steel structures elements, as well as the development of an effective method for determining the influence of the amount of opening of rigid bolted joints and resistance of mounting bolts to opening of hinged support units on their rigidity as a whole. Application of the offered calculation technique allows to define rigidity of bolted rigid and hinged connections, taking into account their actual work, and also to change it due to change in a diameter of bolts, strengthofthematerial from which they are made, their quantity, a distance between them or a thickness of connecting elements, and also to use an additional resource of the material at the expense of some reduction of maximum stresses in the calculated cross sections of elements.