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CHAPTER 5. COASTAL STRUCTURE MODELS
5.4.4 Vertical-Wall Model Scale Selection
The selection of linear scales for vertical-wall structures is largely based on
practical considerations such as maximum wave tank water depth, maximum wave height generating capability, and the response characteristics of
available pressure-sensing instruments. Hudson, et al. (1979) reference a
number of studies (conducted in the 1960’s), and they noted that most of
these studies had linear scales between 1:20 and 1:50. Since that time, major laboratories have acquired prototype-scale wave tanks that allow testing
of vertical-wall structures and caissons at near-prototype scale.
5.4.5 Vertical-Wall Model Construction
The majority of model tests on vertical-wall structures focus on measuring
pressures and impacts on the vertical wall. These models can be constructed
out of any convenient, rigid material, such as wood, steel, plastic, etc. The
model should be ballasted sufficiently (or rigidly fixed to the wave flume) to
prevent movement under wave loading. Pressure sensors can be mounted
directly on the wall, flush with the external surface.
An alternate model technique for determining loads on a vertical wall
is to measure the total force and overturning moment of the structure using strain gages mounted on the wall support points. The drawback to
this method is the loss of information regarding the pressure distribution.
Additionally, force loads due to compression and hammer shock will not
scale the same as nonshock pressures. Therefore, this situation needs to be
avoided in the model.
Vertical-walled monolithic structures usually have sufficient mass to be
stable against wave forces. However, if model stability tests are required,
the structure’s weight and mass distribution must be scaled according to
the Froude criterion.
5.5 Composite Structures
Composite structures have a rubble-mound base that absorbs a greater
portion of the incident wave energy. The base can also trigger wave breaking
so the wave does not break directly on the vertical portion of the structure.
This tripping of the wave can reduce potentially high shock pressures on
the vertical wall.
Physical models of composite structures should be scaled according to
the Froude criterion, and the rubble-mound base must be designed so that
viscous scale effects related to flow through the rubble structure are minimized. This modification is discussed in the section of this Chapter dealing
CHAPTER 5. COASTAL STRUCTURE MODELS
5.4.4 Vertical-Wall Model Scale Selection
The selection of linear scales for vertical-wall structures is largely based on
practical considerations such as maximum wave tank water depth, maximum wave height generating capability, and the response characteristics of
available pressure-sensing instruments. Hudson, et al. (1979) reference a
number of studies (conducted in the 1960’s), and they noted that most of
these studies had linear scales between 1:20 and 1:50. Since that time, major laboratories have acquired prototype-scale wave tanks that allow testing
of vertical-wall structures and caissons at near-prototype scale.
5.4.5 Vertical-Wall Model Construction
The majority of model tests on vertical-wall structures focus on measuring
pressures and impacts on the vertical wall. These models can be constructed
out of any convenient, rigid material, such as wood, steel, plastic, etc. The
model should be ballasted sufficiently (or rigidly fixed to the wave flume) to
prevent movement under wave loading. Pressure sensors can be mounted
directly on the wall, flush with the external surface.
An alternate model technique for determining loads on a vertical wall
is to measure the total force and overturning moment of the structure using strain gages mounted on the wall support points. The drawback to
this method is the loss of information regarding the pressure distribution.
Additionally, force loads due to compression and hammer shock will not
scale the same as nonshock pressures. Therefore, this situation needs to be
avoided in the model.
Vertical-walled monolithic structures usually have sufficient mass to be
stable against wave forces. However, if model stability tests are required,
the structure’s weight and mass distribution must be scaled according to
the Froude criterion.
5.5 Composite Structures
Composite structures have a rubble-mound base that absorbs a greater
portion of the incident wave energy. The base can also trigger wave breaking
so the wave does not break directly on the vertical portion of the structure.
This tripping of the wave can reduce potentially high shock pressures on
the vertical wall.
Physical models of composite structures should be scaled according to
the Froude criterion, and the rubble-mound base must be designed so that
viscous scale effects related to flow through the rubble structure are minimized. This modification is discussed in the section of this Chapter dealing