ARDIENTE

MECHANICS
2.B Unit with Ribs
For the calculation of the ribs, the same simplification
schemes explained in case 2.A (Fig. XX) is considered.
Moreover, only calculations of deflection are needed in
this approach, since the previous analysis proved that
thickness over 5 mm was resistant against braking
loads. Nevertheless, complete hand calculations were
developed in order to check the results and compare
them with Diana (see Appendix).
Firstly, the structural behaviour of a rib that supports
a 1m wide flat sheet is analysed. The self-weight of
the flat sheet is neglected, so the only force that is
considered is the wind load of 1 kN/m 2 applied from
the top side of the rib (Fig. 86). If we consider 1 m wide
of the flat sheet around the rib, it means that a wind
force of 1kN/m is applied to each rib.
Secondly, an analysis of the wind load from the top
and lateral side of the rib was evaluated in the hand
calculations for deformation. For the calculation of the
deformation, an average between simple supported
and fixed beam deformation was performed, in order to
consider the rest of the forces of the structure. In this
case, since the ribs will be main structural elements,
a deformation less than 1 mm is demanded. In the
end, it could be seen that the top wind load was more
critical for the structural behaviour of the rib, but with
a small difference.
The initially expected dimensions of the ribs in the hand
calculations were increasing gradually, achieving a final
dimension of b=6mm and h=70mm. Nevertheless, like
in the previous cases, the simplification shape leads to
non-reliable results, therefore Diana analysis needs to
be performed and checked.
Finally, an acceptable deflection of under 0.5 mm
was obtained in both cases of wind load. Therefore,
the next step is to calculate the distance between the
calculated ribs.
FIGURE 87: DEFLECTION TOP LOAD
1.0 m
b
h
without self
weight
FIGURE 86: CASE 2B - BEAM SECTION
FIGURE 88: DEFLECTION SIDE LOAD
Top Wind Load
Results H. Calculations Diana Required
δ max 1.85 mm - 0.39 mm in middle of DE <1 mm
TABLE 16: RESULTS TOP WIND LOAD
Side Wind Load
Results H. Calculations Diana Required
δ max 0.08 mm 0.38 mm in D <1 mm
TABLE 17: RESULTS SIDE WIND LOAD
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