Pile Design and Construction Practice, Fifth edition

430 Piling for marine structures
Z max � 23/6.5 � 3.5,
x (m) Z � x/R Mm MA � 10.9Mm Mh (MNm)
0 0 �1.00 �10.9 0 0 �10.9
0.5 0.08 �0.98 �10.7 �0.10 �0.3 �11.0
1.0 1.15 �0.97 �10.6 �0.15 �0.4 �11.0
1.5 0.23 �0.95 �10.4 �0.20 �0.5 �10.9
2.0 0.31 �0.94 �10.2 �0.27 �0.7 �10.9
4.0 0.62 �0.85 �9.3 �0.40 �1.1 �10.4
8.0 1.23 �0.55 �6.0 �0.45 �1.2 �7.2
The maximum bending moment of 11.0 MNm provides a safety factor of 15.4/11.0 � 1.4
against yielding of the steel.
From equation 8.3, the kinetic energy absorption value of the pile for horizontal
movement at the stage of soil rupture at sea-bed level:
� 1
2 � 421 � 1363�1000 � 287 kJ
In a similar manner to that set out above, it is possible to obtain pile head deflections and
bending moments for various stages of horizontal loading up to the stage of yielding of the
steel and hence to draw curves of deflection and energy absorption against horizontal load.
The deflection of the pile at sea-bed level caused by a lateral force of 421 kN applied at
the sea bed can be calculated using Randolph’s curves (Section 6.3.8).
Effective Young’s modulus of equivalent solid section pile:
� E� p � 4 � 2 � 105 � 0.024
��0.654 � 34.2 � 103 MN�m2 An average constant soil modulus of 3.3 MN/m 2 from Figure 8.19b was used to calculate
pile deflections and bending moments. For undrained loading take Poisson’s ratio v u � 0.5.
Shear modulus
G* � 1.1(1 � 0.75 � 0.5) � 1.5 MN�m2 � Gc �
3.3
2(1 � 0.5) � 1.1 MN�m2 Critical length
Homogeneity factor � 1
In Figure 6.36a,
yr 0G c
H 0 � E� p
G c� 1�7
�
At 0.5 m below sea bed
z/l c � 0.5/22.9 � 0.02 m
34.2 � 103
� lc � 2 � 0.65� 1.5
y � 0.65 � 1.5
0.421 �
� 2�7
� 22.9 m
34.2 � 103
1.5 � 1�7
� 9.7y
MB � 0.421 � 6.5Mh � 2.74Mh (MNm)
M � MA � MB (MNm)