UNDERCRANED BEAMS MADE OF PERFORATED I-beams AND ASSESSMENT OF THEIR FATIGUE STRENGTH

Abstract

Steel crane beams are the frame elements that are damaged most often. This is explained by the operating conditions of crane beams, the effect of significant concentrated forces, the dynamic nature of loads, etc. It should be noted that the main studies on the fatigue strength of crane beams are related to heavy and very heavy operating modes of cranes. There are not enough works related to medium, and even more so to light modes of work, and if they were carried out, they were not reflected in the literature. This fact is quite simply explained by the circumstances that at the level of cyclicity, which refers to the classes of use С0, С1, С2, С3, the fatigue strength remains practically constant, which is reflected in the design standards, where it is indicated that with the number of load cycles N< 10⁵ endurance calculation is not required. For overhead cranes with a load capacity of up to 500 kN, under-crane beams using perforated I-beams are proposed. Taking into account the results of experimental studies and the level of maximum stresses at the level of (0.7...0.8)Ry, it can be concluded that at N<1.25.10⁵ the fatigue strength of beams made of perforated I-beams is ensured. Perforated beams can be obtained from profiles that differ in height and cross-sectional area, steel strength. Such structural forms have recently been increasingly used due to their undeniable advantages compared to solid and lattice structures using rolled profiles, despite the slight increase in costs associated with the production of a developed profile. In addition, perforated I-beams in combination with rolled sheets, brands, channels and other profiles allow you to create a wide variety of structural forms that satisfy any requirements.