PSI - Issue 57

Mathias Euler et al. / Procedia Structural Integrity 57 (2024) 298–306 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

300

3

In respect of the crane service, the crane-induced concentrated forces do not stand still as force F in Figure 2, but travel along the crane runway beam. Therefore, the stress components of the multiaxial stress state superpose each other with a phase shift in time. That means that each section of the crane runway beam is exposed to the peak values of all local stress components, but not simultaneously. Thus, the principal stress direction permanently changes over time. Such a type of repeated loading is denoted as non-proportionalmultiaxial fatigue action with rotating principal axes (Seeger, 1996). The knowledge of the local stresses, their stress ranges and their interaction are of particular importance for the fatigue verification according to EN 1993-1-9 (2005). In this paper, a design proposal is presented how to check the fatigue resistance of flange-to-web connections and of continuous rail welds of crane runway beams with respect to the local stresses caused wheel load introduction. The proposal is based on new test results.

Fig. 2. Stresses of a crane runway beam with centric wheel load F at midspan: (a) cross section, (b) structural system with loading, (c) schematic stress distribution in the web at section A-A according to advanced strength theory (theory of shells)

Nomenclature a

weld size wheel load

F I rf

moment of inertia of load-distributing top chord

eff effective loaded length of flange-to-web connection according to EN 1993-6 (2006), Section 5.7.1 eff,fat effective loaded length of continuous rail welds acc. to (Euler, 2017) p pressure  ⊥ normal stress (nominal value) in the web transverse to the longitudinal beam axis ¯  ⊥ normal stress (nominal value) in the rail welds transverse to the longitudinal weld axis  || normal stress (nominal value) in the web along the longitudinal beam axis   C characteristic reference value of fatigue resistance  || shear stress (nominal value) in the web along the longitudinal beam axis t w web thickness

2. State of the art

2.1. Wheel loaded flange-to-web connections

The local stresses  ⊥ in the web of a crane runway beam can be calculated according to EN 1993-6 (2006) by means of the effective loaded length eff which is obtained from Eq. (3). The peak value of the compressive stress  ⊥ in the web is determined by Eq. (1) where p max is the maximum pressure at the top edge of the web directly under the wheel load according to Eq. (2) where t w stands for the web thickness.