Best Practices Magazine - issue nº1 - English

Our experts I Structural Calculation
Calculation types: general and
individual
The calculation is carried out in two
stages:
1. General analysis of the structure
Normally filiform, two-dimensional (2D)
models with second order calculations
applying the finite element method are
used. In some types of installations, calculations
are also frequently done via 3D models
in accordance with the EN 1993-1-1.
This analysis must incorporate the modelling
of the actual behaviour of the connection
between the upright-beams and
the frame-ground.
Example of down‐aisle analysis
2. Individual verification of pieces
Once the overall analysis is performed, it is
vital to check the correctness of the design
by verifying the buckling and the tensions of
the pieces that make up the racking.
Basically, the following items are verified:
- General stability of the installation.
- Stress state of frames: uprights and
diagonals.
- Base plates: pressure on the slab and
anchorage.
- Beams: buckling and stress state.
- Connectors.
General analysis: structural model
For general analysis, it is usual to consider
two, two-dimensional (2D) structures in
concurrent vertical and perpendicular layouts
with respect to the storage aisles.
In the model calculation, the following requirements
are observed:
General analysis
• Filiform model.
• System lines through the CG (centre of
gravit y) of the gross sec tion, or also through
the CG of the actual cross section.
Overall analysis of a 2D structure
Example of cross‐aisle analysis
• Terms of section corresponding to the
gross section of the pieces (or also of the
actual cross section).
In this analysis the aim is to obtain:
- The internal forces on the different pieces
for their subsequent verification,
combining the down-aisle and crossaisle
calculations.
- Checking the overall stability of the
installation.
It includes two types of analysis:
- Down-aisle analysis: analysis in 2D on a
vertical layout parallel to the load aisles.
This analysis also includes the semi-rigid
connections of the upright-beam and
upright-floor, obtained by testing.
- Cross-aisle analysis: analysis in 2D on a
vertical layout perpendicular to the load
aisles. Usually involves the articulated
upright-floor joint.
In both cases, the global imperfection can
be modelled as:
- The tilt of the agreed uprights to the
imperfection.
- Horizontal forces at the height of
the load levels corresponding to the
imperfection.
Type of analysis according to the
classification of the structure
This classification is based on the relationship
of the expected load design in regards
to the critical load of the structure. According
to the coefficient obtained by this re-
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