PSI - Issue 75

Elena Sidorov et al. / Procedia Structural Integrity 75 (2025) 276–288 Elena Sidorov et al. / Structural Integrity Procedia (2025)

277

2

1. Introduction Crane runway beams are subjected to frequently recurring stresses due to the introduction of wheel loads from cranes. If a crane runway beam supports a light top-running overhead bridge crane as shown in Figure 1a, it is often made of a hot-rolled I section with a flat bar of structural steel used as crane rail that is attached to the top flange of the beam’s I section by fillet welds. These rail welds are exposed to multi-axial stresses caused by the local wheel load introduction and the global beam bending and are, therefore, at risk of fatigue. A survey among European steel construction companies in 2019, whose outcome has been published in (Kuhlmann et al., 2022) revealed that the following rail weld configurations are commonly used: (i) continuous rail welds as shown in Figure 1 b, (ii) chain intermittent rail welds as shown in Figure 1c and d, and (iii) staggered intermittent rail welds as shown in Figure 1e. The rail welds have to be verified against fatigue, preferably with the nominal stress concept. For the first time, the new Eurocode generation, in particular prEN 1993-6 (2024) and prEN 1993-1-9 (2024), provides fatigue design rules for continuous and intermittent rail welds based on nominal stresses. The background of the proposed nominal stress formula for continuous rail welds in connection with the corresponding detail categories has already been described by following references in detail: Euler (2017), Euler & Kuhlmann (2018) and Kuhlmann et al. (2015, 2016). Therefore, the focus of this paper is laid on intermittent rail welds. It investigates the basic assumptions of the newly proposed nominal stress formula and discusses possibilities to extend the application range.

Fig. 1. Supporting structure of a travelling overhead crane: a) example of a crane installation; crane rail fastening through b) continuous and c) intermittent rail welds; d) chain intermittent rail welds, e) staggered intermittent rail welds. Explanation: 1 – crane rail, 2 – crane runway beam, 3 – overhead travelling crane, 4 – crane wheel

Nomenclature a

rail weld size rail width wheel load

b r F

spacing of intermittent rail welds gap size simulating technical contact

g

g con

weld length rail height

h

h r L

length of crane runway beam effective loaded length

ℓ eff

p maximum vertical force in both welds per unit length [N/mm]; called ‘weld pressure’ in the paper σ nom nominal stress in the rail welds caused by wheel load introduction [N/mm²]