EI 02C097
01 Jul 97
The following table shows the computation of the values of
certain that the two methods could not have been brought
deflection and bending moment as a function of depth, using
into perfect agreement. An examination of Figure 4-27a
the above equations. The same problem was solved by
shows that is impossible to fit a straight line through the
plotted values of Es versus depth; therefore, Es = kx will not
computer and results from both methods are plotted in
Figure 4-28. As may be seen, the shapes of both sets of
yield a perfect solution to the problem, as demonstrated in
curves are similar, the maximum moment from the hand
Figure 4-28. However, even with imperfect fitting in
method and from computer agree fairly well, but the
Figure 4-27a and with the crude convergence shown in
computed deflection at the top of the pile is about one-half
Figure 4-27b, the computed values of maximum bending
the value from the nondimensional method. One can
moment from the hand solution and from computer agreed
conclude that a closed convergence may have yielded a
remarkably well. The effect of the axial loading on the
smaller value of the relative stiffness factor to obtain a
deflection and bending moment was investigated with the
slightly better agreement between the two methods, but it is
computer by assuming that the pile had an axial load of
M (in. lb/106)
Depth (in.)
y (in.)
z
Ay
AM
0
0.0
2.43
2.29
0.0
0
17
0.2
2.11
1.99
0.198
0.499
34
0.4
1.80
1.70
0.379
0.955
50
0.6
1.50
1.41
0.532
1.341
67
0.8
1.22
1.15
0.649
1.636
84
1.0
0.962
0.91
0.727
1.832
101
1.2
0.738
0.70
0.767
1.933
118
1.4
0.544
0.51
0.772
1.945
151
1.8
0.247
0.23
0.696
1.754
210
2.5
-0.020
-0.02
0.422
1.063
252
3.0
-0.075
-0.07
0.225
0.567
294
3.5
-0.074
-0.07
0.081
0.204
336
4.0
-0.050
-0.05
0.0
0
100 kips. The results showed that the groundline deflection
results, not shown here, yielded an ultimate load of 52 kips.
increased about 0.036 inches, and the maximum bending
The deflection corresponding to that load was about
moment increased about 0.058 106 in-lb; thus, the axial
3.2 inches.
load caused an increase of only about 3 percent in the values
computed with no axial load. However, the ability to use an
(7) Apply global factor of safety (step 7). The selection
axial load in the computations becomes important when a
of the factor of safety to be used in a particular design is a
portion of a pile extends above the groundline. The
function of many parameters. In connection with a particular
computation of the buckling load can only be done properly
design, an excellent procedure is to perform computations
with a computer code.
with upper-bound and lower- bound values of the principal
factors that affect a solution. A comparison of the results
(6) Repeat solutions for loads to obtain failure moment
may suggest in a particular design that can be employed with
(step 6). As shown in the statement about the dimensions of
safety. Alternatively, the difference in the results of such
the pile, the ultimate bending moment was incremented to
computations may suggest the performance of further tests
find the lateral load Pt that would develop that moment. The
of the soil or the performance of full-scale field tests at the
4-35
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