Hydrodynamic Loads Induced By Earthquakes
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Authors
Garrison, C.J.
Berklite, R.B.
Subjects
Advisors
Date of Issue
1972
Date
1972
Publisher
Language
Abstract
When bottom mounted structures of large
displacement are immersed in the sea. earthquake
induced hydrodynamic loads may become
important design factors. Specifically, as
the earth oscillates, a bottom mounted structure
is forced to describe time dependent
motion in an otherwise still fluid. As a
result, hydrodynamic loads in addition to the
inertial loads of the structure itself are
induced. In this paper, a theoretical approach
to the calculation of these hydrodynamic loads
is outlined and numerical results are presented
for several submerged configurations . Practical
geometries considered include a submerged 011
storage tank configuration and a conical configuration
as has been proposed for offshore
drilling rig designs for deployment in the
Arctic. Also, computations were carried out for
a sphere and vertical circular cylinder and
various comparisons with classical results are
made.
Numerical results for these submerged
structures are presented in the form of a
dimensionless hydrodynamic load parameter or
added mass coefficient. Results corresponding
to a number of different water depths are presented
to show the rather sizable effect of
the relative water depth on the hydrodynamic
force. It is shown that for typical earthquake
frequencies, the effect of the free water surf
ace is to reduce the hydrodynamic loads in
comparison to the corresponding infinite depth
values .
Experimental results obtained by vibration
testing are presented for a submerged sphere
and a vertical circular cylinder. These results
show excellent agreement with the theoretical
results .
Type
Conference Paper
Description
This paper was prepared for presentation at the Fourth Annual Offshore Technology Conference
held in Houston, Tex., May 1-3, 1972 .
Series/Report No
Department
Organization
Naval Postgraduate School (U.S.)
Identifiers
NPS Report Number
Sponsors
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Format
14 p.
Citation
Distribution Statement
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.