Ultimate Limit State Design of Rail Welds of Crane Girders According to EN 1993-6
If crane runway girders are designed with flat steel rails, the welding of these rails is always a detail for the design. As a rail fixing, you can generally select between continuous and intermittent fillet weld. The following article provides an overview of the design processes and their specific features, especially when using the EN 1993‑6.
Arrangement Options of Rail Fillet Welds
There are two variants of intermittent fillet welded connections. These are shown in the following figure from .
Weld sections can be arranged either on opposite sides or staggered. The staggered arrangement is disadvantageous for the design since only one weld can be used for the transfer of horizontal loads. The third option that is not shown in the figure above, is a continuous fillet weld along the entire rail length, of course.
Effective Loaded Length
The determination of the corresponding weld stresses requires the calculation of effective loaded lengths. EN 1993‑6 differentiates between three options and provides the corresponding formulas for the calculation of leff in Table 5.1.
In this case, leff refers to the underside of the top flange. However, the upper surface of the top flange is governing for the weld design. Therefore, leff is reduced by double flange thickness tf.
Ultimate Limit State Designs
Rail weld stresses are calculated according to Directional Method specified in . In this case, the stresses refer to the bisecting surface of the fillet weld. According to , (NA) Section 4.5.2, the minimum structural thicknesses must be kept for the weld. The standard requires a weld the minimum thickness of at least 3 mm or the application of the following formula:
The eccentric wheel load of 1/4 of the rail head width is not taken into account at the ultimate limit state according to . Therefore, the design due to wheel loading is always performed.
Case 1: Continuous Rail Weld
For intermittent rail fillet welds, it is necessary to check whether the weld length lw is smaller than the calculated loaded length leff. Generally, the minimum of both values is governing for the design.
Case 2: Intermittent Rail Weld on Opposite Sides
Case 3: Staggered Intermittent Rail Weld
Since the horizontal load is only applied to a weld section in the case of the staggered arrangement of welds, Divisor 2 is omitted in terms of HEd.
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- Craneway and weld stress analysis
- Craneways and weld fatigue design
- Deformation analysis
- Plate buckling analysis for wheel load introduction
- Stability analysis for lateral torsional buckling according to the second-order analysis of torsional buckling (1D FEA element)
For the design according to Eurocode 3 the following National Annexes are available:
- DIN EN 1993-6/NA:2010-12 (Germany)
- NBN EN 1993-6/ANB:2011-03 (Belgium)
- SFS EN 1993-6/NA:2010-03 (Finland)
- NF EN 1993-6/NA:2011-12 (France)
- UNI EN 1993-6/NA:2011-02 (Italy)
- LST EN 1993-6/NA:2010-12 (Lithuania)
- NEN EN 1993-6/NB:2012-05 (The Netherlands)
- NS EN 1993-6/NA:2010-01 (Norway)
- SS EN 1993-6/NA:2011-04 (Sweden)
- CSN EN 1993-6/NA:2010-03 (Czech Republic)
- BS EN 1993-6/NA:2009-11 (United Kingdom)
- CYS EN 1993-6/NA:2009-03 (Cyprus)
In addition to the National Annexes (NA) listed above, you can also define a specific NA, applying user-defined limit values and parameters.
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