Civil Engineering Reference
In-Depth Information
5.13 Unworked examples
5.13.1 Example 19 - section properties
Determine the principal axis properties
I
y
,
I
z
of the half box section shown in
Figure 5.45a.
5.13.2 Example 20 - elastic stresses and deflections
The box section beam shown in Figure 5.45b is to be used as a simply supported
beam over a span of 20.0 m. The erection procedure proposed is to fabricate the
beamastwohalfboxes(therighthalfasinFigure5.45a),toerectthemseparately,
andtopullthemtogetherbeforemakingthelongitudinalconnectionsbetweenthe
flanges.The total construction load is estimated to be 10 kN
/
m
×
20 m.
(a) Determine the maximum elastic bending stress and deflection of one
half box.
(b) Determinethehorizontaldistributedforcerequiredtopullthetwohalfboxes
together.
(c) Determine the maximum elastic bending stress and deflection after the half
boxes are pulled together.
400 200
100 200
200
800
200
20
20
20
20
20
20
1000
10
500
1000
25
20
25
400
800
(c) I-section with
off-centre web
(a) Half box section
(b) Box section
600
Q
D
=150kN
Q
=200kN
I
q
D
=50kN/m
q
=20kN/m
I
30
16
1000
20
4500
1500
300
(d) Monosymmetric I-section
(e) Propped cantilever
Figure 5.45
Unworked examples.
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