Civil Engineering Reference
In-Depth Information
Flexibility coe
cient is:
f
11
=
(
f
11
)
AB
+
(
f
11
)
BC
l
3
E
c
(60)
I
c
+
l
3
E
c
(7)
I
c
=
.
The statically indeterminate bending moment at B at
t
=
60 is:
F
1
=−
D
1
/
f
11
.
Substitution of
E
c
(60)
=
1.26
E
c
(7) in the above equations gives
F
1
=−
0.0697
ql
2
.
The broken line (a) in Fig. 4.3(c) represents the bending moment
diagram immediately after removal of the formwork of BC. If after this
event the beam is released again, creep will produce, between
t
=
60,
and
∞
, the following change in displacement:
∆
D
1
=
(
∆
D
1
)
AB
+
(
∆
D
1
)
BC
.
The
fi
rst term on the right-hand side of this equation represents
e
ff
ects of creep on span AB due to load
q
introduced at
t
=
7 and the
statically indeterminate force
F
1
introduced at
t
=
60; thus,
ql
3
24
E
c
(7)
I
c
0.0697
ql
3
3
E
c
(60)
I
c
φ
(
∆
D
1
)
AB
=
[
φ
(
∞
, 7)
−
φ
(60, 7)]
−
(
∞
, 60).
On BC, the distributed load
q
and the force
F
are introduced at
t
=
7;
creep produces a change in slope at B
ql
3
24
E
c
(7)
I
c
0.0697
ql
3
3
E
c
(7)
I
c
(
∆
D
1
)
BC
=
φ
(
∞
, 7)
−
φ
(
∞
, 7).
Substitution of the values of
φ
and
E
c
(60)
=
1.26
E
c
(7) in the above
equations gives
ql
3
E
c
(7)
I
c
∆
D
1
=
0.0720
.
Search WWH ::
Custom Search