On the specifics of the formation of stress-strain state of the wall of crane beams during crane movement

It is known that local stresses in the upper wall zone of crane beams determine their fatigue strength, especially in beams for heavy-duty cranes (7 K and 8 K). The local stress state in the upper wall zone of crane beams is formed by compressive and bending stresses. Compressive stresses are determined by the well-known formula of B.M. Broude and correlate well with experimental results since they depend only on the vertical pressure of the crane wheel. On the contrary, to determine local bending stresses, a bending moment is used, the value of which has a significant uncertainty in the used design parameters (eccentricity e and lateral force Qt). This uncertainty can be neglected when checking static strength of the upper wall zone, but to assess the fatigue strength, it is necessary to use more specific values that can be experimentally verified as a design parameter. It is recommended to use the angle of rotation of the upper chord of the beam as such a value. The angle of rotation takes into account not only the above-mentioned parameters, but also integrally includes the state of the crane runways when the crane moves with a skew, the degree of wear of the crane rails and the degree of its joint work with the beam chord, i.e., the condition of the rail fastenings to the beam chord. The angle of rotation of the beam chord is a universal characteristic for determining local bending stresses. However, at present, there is not enough statistical data on the value of this parameter, and this gap needs to be filled. In this article, an attempt is made to analytically evaluate the feasibility of using the angle of rotation of the beam chord when determining local stresses in comparison with the traditional one.