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MODELLING OF WAVE OVERTOPPING LOADS ON A BUILDING BEHIND A RUBBLE
MOUND BREAKWATER USING A 2DV NUMERICAL MODEL AND THEIR APPLICATION IN
BUILDING DESIGN
Phoebe Watson, Arup Ireland, phoebe.watson@arup.com
Ioannis Avgeris, Arup Ireland, ioannis.avgeris@arup.com
Francisco Jaime F.,
Universidad de Cantabria
,
francisco.jaime@unican.es
Javier L. Lara,
Universidad de Cantabria
,
jav.lopez@unican.es
INTRODUCTION
This study considers the wave overtopping loads on a
building behind a rubble mound breakwater using 2D
numerical modelling. The building will be used as Coast
Guard station in Greystones Marina, which is located on
the Irish Sea. Similar studies, using physical modelling,
were carried out recently by Watson et al. (2018) and
Park et al. (2017). The applicability of the numerical
model in predicting wave overtopping forces is discussed.
Appropriate design wave conditions are considered and
the resultant loads are assessed to determine their
impact on the design of the proposed building.
DESCRIPTION OF THE NUMERICAL MODEL
In order to simulate wave-structure interaction, the two-
dimensional (2DV) CFD numerical model IH2VOF was
used. The validation of this model for the numerical
analysis of wave overtopping of rubble mound
breakwaters is described in Losada et al. (2008). The
numerical model was constructed at a 1:1 scale. The most
onerous cross-section of the breakwater was modelled,
while the building was located 11m behind the front face
of the recurved crown wall. Design storm events were
selected based on the design life of the building and the
design storm events for which the breakwater was
designed. Simulations were carried out for a set of 3 sea
states, considering irregular Jonswap type wave with 4
random time series of irregular waves generated and
simulated per sea state. This involved 12 numerical
simulations in total, each with a 3600 seconds duration.
Wave overtopping pressures on the seaward face and roof
of the building were calculated using the model. The effect
of air entrainment was not considered in the water mass,
providing slightly conservative results for a safer design.
NUMERICAL RESULTS
The pressure distribution over the face of the building,
derived from the model, was converted to a total wave
overtopping force over time with an application point
calculated for the equivalent point load of the pressure
distribution, as shown in Figure 1. High impulsive loads
from discrete wave overtopping events were identified.
The impact of impulsive wave loading was then
assessed, as discussed in Cuomo et al. (2010).
APPLICATION IN BUILDING DESIGN
The integrated total force was used to identify wave
overtopping events which had a significant impact on
the face of the building. The pressure time series of
these events were extracted for further analysis.
Figure 1 –
Wave Overtopping Force with application
height distribution for the 1 in 100 year storm event
The duration of impact loads was compared to the
natural frequency of a cantilever wall and load
magnitudes converted to a maximum envelope of quasi-
static loads. This was further simplified for application in
the structural model of the building by defining banded
heights for the load application. The analysis allowed for
significant optimization of the detailed design when
compared with the conceptual design, which had been
based on empirical methods for breakwater crown walls.
ACKNOWLEGDEMENTS
We would like to thank the Office of Public Works in
Ireland for permitting us to present this project.
REFERENCES
Cuomo, Allsop, Bruce, Pearson, (2010): Breaking wave
loads at vertical seawalls and breakwaters, Coastal
Engineering, ELSEVIER, vol. 57, pp. 424-439
Losada, Lara, Guanche, Gonzalez-Ondina (2008)
Numerical analysis of wave overtopping of rubble mound
breakwaters Coastal Engineering, ELSEVIER, vol. 55, pp.
47–62.
Park, Tomiczek, Cox, van de Lindt, Lomonaco, (2017)
Experimental modeling of horizontal and vertical wave
forces on an elevated coastal structure, Coastal
Engineering ELSEVIER, vol. 128, pp. 58–74
Watson, Nuyts, Murphy, Lizondo, Anastasaki, Avgeris,
(2018) Wave overtopping pressures on a building behind
a rubble mound breakwater: An experimental study Proc.
Coastlab 2018.
