Civil Engineering Reference
In-Depth Information
Figure 3.10
Profiled sheeting during construction
Flexure and vertical shear
The most adverse loading for sagging bending is shown in Fig. 3.10, in
which the weight of the sheeting alone in span BC is neglected. Elastic
analysis gives the maximum design bending moments as:
•
sagging:
1.95
2
M
Ed
=
0.0959
×
(3.6
+
1.5)
×
=
1.86 kN m/m
•
hogging (both spans loaded):
M
Ed
= 0.125 × 5.1 × 1.95
2
=
2.42 kN m/m
1.0, the design resistance is
M
Rd
=
M
pa
=
6.18 kN m/m
, which
With
γ
A
=
is ample.
Vertical shear rarely governs design of profiled sheeting. Here, the
maximum value, to the left of point B in Fig. 3.10, is
V
Ed
=
0.625
×
5.1
×
1.95
=
6.2 kN/m
which is far below the design resistance of about 60 kN/m.
Deflection
The characteristic permanent load for the sheeting is 2.66
3.66
kN/m
2
. It is assumed that the prop does not deflect. The maximum deflec-
tion in span AB, if BC is unloaded and the sheeting is held down at C, is
+
1.0
=
wL
EI
4
366
. .
. .
×
195
4
e
δ
max
=
=
.
=
25
mm
(3.38)
185
185
×
0 21
×
0 548
ap
This is span/784, which is satisfactory.
3.4.2
Composite slab - flexure and vertical shear
This continuous slab is designed as a series of simply-supported spans.
For bending, the reactions from the beams are assumed to be located as in
