Civil Engineering Reference
In-Depth Information
Fig. 3.10, so
L
e
3.90 m. For vertical shear, the span is taken as 4.0 m, so
that the whole of the slab is included in the design loading for the beams.
From Section 3.2, the characteristic loadings are:
=
•
g
k
=
2.54 (slab)
+
1.3 (finishes)
=
3.84 kN/m
2
•
q
k
=
5.0 (imposed)
+
1.2 (partitions)
=
6.2 kN/m
2
The design ultimate loadings are:
•
permanent:
g
d
=
3.84
×
1.35
=
5.18 kN/m
2
•
variable:
q
d
=
6.2
×
1.5
=
9.30 kN/m
2
The mid-span bending moment is
M
Ed
=
14.48
×
3.9
2
/8
=
27.6 kN m/m
For the bending resistance, from Equation 3.4,
N
c,f
=
1178
×
0.35/1.0
=
412 kN/m
(3.39)
The design compressive strength of the concrete is 0.85
=
14.2 N/mm
2
so, from Equation 3.5, the depth of the stress block, for full
shear connection, is
×
25/1.5
x
=
412/14.2
=
29.0 mm
(3.40)
This is less than
h
c
(which can be taken as 95 mm for this profile (Fig. 3.9)),
so from Equation 3.6 with
d
p
=
120 mm,
M
Rd
=
412(0.12
−
0.015)
=
43.3 kN m/m
(3.41)
The bending resistance is sufficient, subject to a check on longitudinal
shear.
The design vertical shear for a span of 4 m is
V
Ed
=
2(5.18
+
9.3)
=
29.0 kN/m
For the shear resistance, from Equation 3.21 with
d
p
taken as 200 mm,
v
min
=
0.035
×
2
3/2
×
25
1/2
=
0.49 N/mm
2
