Civil Engineering Reference
In-Depth Information
Figure 5.21
Part plan of typical floor slab
From EN 1994-1-1, second-order effects may be neglected in the glo-
bal analysis if the deformations from first-order global analysis increase
the relevant internal action effects by less than 10%. It will be found that
this exemption applies.
It is assumed that the concrete above the profiled sheeting in each floor
slab acts as a reinforced concrete beam of breadth 80 mm (its thickness)
and depth 19 m, spanning 28 m. For simplicity, this span is assumed to be
simply-supported. The lateral stiffnesses of these deep 'beams' and of the
shear walls are so much higher than that of each frame, such as DEF in
Fig. 5.21, that the presence of the frames can be ignored.
Design loadings, ultimate limit state
The force
H
Ed
is greatest when live load is applied to all floors, so the
reduction factor
0.767 (Section 5.7.1) is applicable. From Table 4.4,
the imposed beam loading is
α
n
=
0.767
×
37.2
=
28.5 kN/m
Dead loads are as in Section 5.5.1, except that the design weight of a 4-m
length of internal column has increased from 16.2 kN to 30.0 kN.
The total permanent load per storey from a 4-m length of the building
is
G
=
23.7
×
19
+
2
×
97.2
+
30
=
675 kN
The imposed load is
Q
=
28.5
×
19
=
542 kN
