Port and Harbor Design 31.4 Suggested Reading 707
Part C | 31.4
sheltered ports or harbors, wave diffraction analysis
is required to derive the appropriate design wave parameters for wave-loading calculation. In general, the
accurate prediction of the wave load is extremely difficult due to the dynamic and nonlinear nature of waves
and the fluid–structure interaction. The magnitude of
wave loads depends not only on the wave height and
wave period, but also on the ratio of wavelength to
the dimension of the structure. If the structure is relatively slender compared to the wavelength, the drag
and inertia forces dominate and the Morison equation
can be used to calculate the wave load. If the structure’s
dimension is larger than the wavelength, the wave reflection will become important and the effect of wave
reflection should be considered in the wave load calculation. If the structure’s dimension is between these
two cases, the effects of wave diffraction will become
important, and the wave-loading calculation will become more complicated. For wave loadings on floating
structures, in additional wave height, wave period, and
structure’s dimension, the wave load will also depend
on the anchor system and the natural frequency of the
floating structure. It needs to be realized that the wave
load and corresponding calculation are different for
breaking and nonbreaking waves. The impact force on
structures caused by wave breaking is significant larger
than the quasi-static wave force used in the most wave
load formulas. For more detailed wave-loading analysis, the major references include USACE (United States
Army Corps of Engineers) Coastal Engineering Manual (CEM) [31.6] and British Standard 6325 [31.28].
National codes and guidelines, and related ocean and
coastal engineering design books can provide further
guidance.
Current
In the marine environment, the magnitude and direction
of a current at a site vary not only with time, but also
with the vertical water-depth profile. The current could
be tidal current, river discharge currents (within the estuary), wind-generated surface currents, wave-induced
currents, and currents caused by vessel propeller wash.
The current load acting on a structure usually consists
of a static component and an oscillatory component.
However, for port or harbor design, in majority cases,
the maximum depth-averaged current under the design storm condition is employed in the current force
formula. For more detail on the current-loading calculations, the reader may refer to [31.6, 28].
31.3.4 Tide and Storm Surge
The water-level change by tide and storm surge will
have effects on structure loads. These effects include
hydrostatic pressure change, soil surcharge change,
change on the mooring line loads and fender load,
change in the wave overtopping rate and corresponding impact force, and change in the wave uplift force on
the pier deck due to the change of the air gap. For port
or harbor structure design, the effects of tide and storm
surge on the load calculation should be considered in
the design.
31.3.5 Ice
In some ports or harbors, the load caused by the sea ice
on the marine structures includes the impact (or thrust)
load from floating drift ice, increased weight and area
(for current load), uplift due to the decrease of the air
gap for pier deck, etc. The above effects need to be considered when performing the port or harbor structure
design.
31.3.6 Tsunamis
Tsunamis are actually one type of long waves. They
are mainly caused by earthquakes. Though heights of
these waves are small in deep water, they can be amplified significantly when these long waves propagate
close to the shore if the sea bottom slope is steep.
Tsunamis could be disasters for port or harbor facilities
and moored vessels. For more details on the mitigation
of tsunami disasters in port planning and design, readers can refer to PIANC [31.30].
31.4 Suggested Reading
This chapter is not intended to be a comprehensive manual on the planning and design of ports and harbors. For
more detailed information on the civil and structural
design of ports and harbors, it is suggested to refer to
more detailed international design standards and publications, such as the following:
Department of Defense, United States of America,
UFC 4-152 Design Piers and Wharves, 2012: This
Unified Facilities Criteria (UFC) document contains
descriptions and design criteria for pier and wharf
construction, including subsidiary, contiguous, and
auxiliary structures. Loading details, regulations,
Part C | 31.4
sheltered ports or harbors, wave diffraction analysis
is required to derive the appropriate design wave parameters for wave-loading calculation. In general, the
accurate prediction of the wave load is extremely difficult due to the dynamic and nonlinear nature of waves
and the fluid–structure interaction. The magnitude of
wave loads depends not only on the wave height and
wave period, but also on the ratio of wavelength to
the dimension of the structure. If the structure is relatively slender compared to the wavelength, the drag
and inertia forces dominate and the Morison equation
can be used to calculate the wave load. If the structure’s
dimension is larger than the wavelength, the wave reflection will become important and the effect of wave
reflection should be considered in the wave load calculation. If the structure’s dimension is between these
two cases, the effects of wave diffraction will become
important, and the wave-loading calculation will become more complicated. For wave loadings on floating
structures, in additional wave height, wave period, and
structure’s dimension, the wave load will also depend
on the anchor system and the natural frequency of the
floating structure. It needs to be realized that the wave
load and corresponding calculation are different for
breaking and nonbreaking waves. The impact force on
structures caused by wave breaking is significant larger
than the quasi-static wave force used in the most wave
load formulas. For more detailed wave-loading analysis, the major references include USACE (United States
Army Corps of Engineers) Coastal Engineering Manual (CEM) [31.6] and British Standard 6325 [31.28].
National codes and guidelines, and related ocean and
coastal engineering design books can provide further
guidance.
Current
In the marine environment, the magnitude and direction
of a current at a site vary not only with time, but also
with the vertical water-depth profile. The current could
be tidal current, river discharge currents (within the estuary), wind-generated surface currents, wave-induced
currents, and currents caused by vessel propeller wash.
The current load acting on a structure usually consists
of a static component and an oscillatory component.
However, for port or harbor design, in majority cases,
the maximum depth-averaged current under the design storm condition is employed in the current force
formula. For more detail on the current-loading calculations, the reader may refer to [31.6, 28].
31.3.4 Tide and Storm Surge
The water-level change by tide and storm surge will
have effects on structure loads. These effects include
hydrostatic pressure change, soil surcharge change,
change on the mooring line loads and fender load,
change in the wave overtopping rate and corresponding impact force, and change in the wave uplift force on
the pier deck due to the change of the air gap. For port
or harbor structure design, the effects of tide and storm
surge on the load calculation should be considered in
the design.
31.3.5 Ice
In some ports or harbors, the load caused by the sea ice
on the marine structures includes the impact (or thrust)
load from floating drift ice, increased weight and area
(for current load), uplift due to the decrease of the air
gap for pier deck, etc. The above effects need to be considered when performing the port or harbor structure
design.
31.3.6 Tsunamis
Tsunamis are actually one type of long waves. They
are mainly caused by earthquakes. Though heights of
these waves are small in deep water, they can be amplified significantly when these long waves propagate
close to the shore if the sea bottom slope is steep.
Tsunamis could be disasters for port or harbor facilities
and moored vessels. For more details on the mitigation
of tsunami disasters in port planning and design, readers can refer to PIANC [31.30].
31.4 Suggested Reading
This chapter is not intended to be a comprehensive manual on the planning and design of ports and harbors. For
more detailed information on the civil and structural
design of ports and harbors, it is suggested to refer to
more detailed international design standards and publications, such as the following:
Department of Defense, United States of America,
UFC 4-152 Design Piers and Wharves, 2012: This
Unified Facilities Criteria (UFC) document contains
descriptions and design criteria for pier and wharf
construction, including subsidiary, contiguous, and
auxiliary structures. Loading details, regulations,