The material type used was linear elastic with material property as given as in above Table.
The structure was made 132" long however the analysis was carried out considering that the
height of the wall above the ground was 120". To model this condition the constraint was applied
to the bottom 12" section by constraining all degrees of freedom for this section. Also the node at
the interfaces between the bottom 12" and structure above the ground was only constraint for UX,
UY, and UZ while the all the rotational freedoms were allowed.
The load applied to the structure was uniform pressure of 0.5 psi. In actual condition the
pressure from the water level will have a gradient increasing from top to bottom. However in this
case the pressure was determined by considering that the maximum pressure applied by the water
level of height `h' can be given by
P = ρgh
where
P = pressure
ρ = density of water
g = acceleration due to gravity
h = height of the water level (120").
Substituting the standard values in the above equation the maximum static pressure applied
by the water level is 0.433 psi. Hence the constant pressure more than the actual maximum
pressure tends to overload the structure and hence can be considered as a attempt to take into
account the dynamic loading of the structure due to the waves in the water body. It should be
noted that the conditions considered for the model would give the worst-case scenario
results. Any attempt to model the actual structure under the more appropriate boundary
condition will result in the performance prediction of the structure better than the one
obtained from the present model.
The results from the present FEA were analyzed with respect to maximum stress and
maximum strain developed in the structure. Figure C5 shows the displacement of the structure.
The maximum displacement as can be expected is observed at the tip of the seawall and is 32".
This value however will be much lower in presence of the wooden frame to which these
seawall structures are attached.
Figure C6 shows first principal stress distribution in the structure. As can be seen from the
figure that the maximum stress is developed at the edge where the structure emerges from the
earth surface or the support condition. The maximum stress value of 8449 psi seems to be larger
than the maximum tensile strength of 6300 psi of the material. However the development of
stresses in this localized area is because of the large deflection allowed by the present model.
Also this analysis being linear elastic in nature doesn't allows for any plastic deformation
effects which can reduce the stress concentration much before such a large stress
concentration is realized.
Figure C7 shows the maximum first principal strain in the structure. As the case should be the
maximum stress and maximum strain region does coincide. However the maximum principle
strain can be observed to be approximately 2.1%, which is far less than the maximum strain to
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