Improvement on Structural Forms of Pile Group Foundations of Deepwater Bridges

Table 1

Dynamic characteristics of the foundations with different forms

Mode	Frequency (Hz) (modal shape)
	Double caps foundation	Three caps foundation	Joint piles foundation	Original foundation
1	1.87 (T-y axis)	1.86 (T-y axis)	0.99 (T-y axis)	0.80 (T-y axis)
2	2.11 (T-x axis)	2.08 (T-x axis)	1.04 (T-x axis)	0.81 (T-x axis)
3	4.08 (R-x axis)	3.38 (R-z axis)	2.41 (R-z axis)	1.93 (R-z axis)
4	5.55 (R-y axis)	4.45 (R-x axis)	4.14 (R-x axis)	3.93 (R-x axis)

T represents the translation of the upper cap towards x or y axis and R represents the rotation of the upper cap around x, y, or z axis.