Civil Engineering Reference
In-Depth Information
The top graphic in Fig. 6.10 indicates that the retaining wall moment increases
during the contraction cycles (rise in temperature) and decreases after expansion.
The variation between the bending moments developed during the different
temperature cycles is most pronounced at the first unrestrained level (level B) and
is nearly equal to 250 percent. Furthermore, the maximum bending movement
developed during the third contraction cycle is 70 percent larger than its
counterpart found at the end of the initial backfill stage.
On the other hand, the bottom graphic in Fig. 6.10 indicates that the end
column moment increases during the expansion cycles (rise in temperature) and
decreases after contraction. The variation between the bending moments
developed during the different temperature cycles is also most pronounced at the
first unrestrained level (level B) and is nearly equal to 500 percent, nearly twice
the corresponding variation found for the retaining wall. Additionally, the
maximum bending moment developed in the end column at the last contraction
cycle is approximately three times larger than the corresponding moment found at
the end of the backfill stage.
Fig. 6.11 illustrates the variation of lateral earth pressure exerted on the
retaining wall with the change in temperature.
36
Roof
'
a
σ
'
ec3
σ
σ
σ
'
ec1
σ
'
cc3
σ
Level D
27
'
cc1
σ
'
ec2
σ
'
ec4
σ
'
Active
σ
Level C
18
'
cc2
'
At Rest
Level B
9
Level A
0
0
0.5
1
1.5
2
2.5
3
3.5
4
σ
'
h
, kips/ft
2
Fig. 6.11
Lateral Earth Pressure behind Rigid Frame (Hardening Soil Backfill)
At the initial backfill stage, the lateral earth pressure developed in the
hardening soil model is approximately equal to the lateral earth pressure at rest,
substantially larger than the active earth pressure determined from Coulomb's
classical earth pressure theory. With increase in temperature causing the
expansion of the rigid frame, the lateral earth pressure increases substantially to
nearly similar values irrespective of the number of cycles, and decreases
considerably after contraction movements. These results are in general qualitative
concordance with those found from the analysis presented in Part 2 earlier. A
comparison of the analysis results presented in the three formed parts is drawn
below.
