This study examines tsunami forces on bridge decks through large-scale laboratory experiments and numerical simulations. A 1:5 scale concrete bridge deck model was installed in a wave flume and subjected to solitary waves of varying heights and clearances between the water and deck. Wave force time histories were recorded and decomposed into quasi-static and slamming components. Numerical simulations matching the experimental conditions showed good agreement with measurements. Both quasi-static and slamming forces increased significantly with wave height and clearance in horizontal and vertical directions. The results provide guidance for estimating tsunami forces on bridges.

1. LARGE–SCALE LABORATORY EXPERIMENT AND NUMERICAL SIMULATION OF
TSUNAMI FORCES ON A BRIDGE DECK
Numerical Simulation
Numerical predictions of the experimental results
using identical wave generation conditions are
performed using a finite element analysis (FEA)
code LS-DYNA. Simulation results match well with
experimental measurements over the wide range
of wave conditions tested. A parametric study is
conducted using numerical simulation
complementing experiment data to examine the
effect of deck clearance on wave forces.
Introduction
Natural disasters, such as hurricane and tsunami,
could cause great damage to coastal structures,
especially bridges. In order to protect coastal
bridges from tsunami damage, a methodology to
accurately estimate tsunami forces on bridge deck
superstructures valuable for future design
guidelines is developed in this study.
Conclusion
• Both high-frequency slamming and low-frequency
quasi-static components contribute significantly to
the total horizontal and vertical wave forces.
• For un-broken waves, both slamming and quasi-static
force components increase with wave height.
• For broken waves, the maximum slamming force
components have a large variance, while the variance
of the maximum quasi-static component is small.
• The simulation and experiment measurements agree
well.
• The quasi-static and slamming components in
horizontal and vertical directions both have strong
correlation with wave height and clearance.
Research Objectives and Goals
Previous studies have revealed that both the
vertical and horizontal wave forces contains two
components: a high frequency impulsive slamming
component, and a lower frequency quasi-static
component. The object of this study is to
investigate and quantify the influence of wave
height and deck clearance (the distance between
still water level and the bottom of the structure)
to the wave forces in the horizontal and vertical
directions due to solitary waves by conducting an
experiment and numerical simulations.
Figure 1. Damage to the U.S. 90 Biloxi Bay Bridge caused by Hurricane Katrina
(Solomon Yim, Oregon State University)
Experimental Setup
A 1:5 concrete bridge deck model is designed and
constructed, and installed in the OSU HWRL Large
Wave Flume. Two horizontal and six vertical load
cells are used to record the wave force time
histories on the structure.
Table 1. Description for test cases, letters "NB" indicates non-broken waves and
"B" indicates broken waves
Water level, h (m) Wave Height, H(m) Wave condition
2.00 0.36 NB
2.00 0.42 NB
2.00 0.55 NB
2.00 0.70 NB
2.00 0.90 B
2.00 1.00 B
2.00 1.20 B
2.00 1.40 B
1.90 0.46 NB
1.90 0.52 NB
1.90 0.65 NB
1.90 0.80 B
1.90 1.00 B
1.90 1.10 B
1.90 1.30 B
Figure 2. Side view of the experiment model setting
Figure 3. Snapshots of a solitary wave impact on the bridge deck model
(HWRL, Oregon State University)
Wave Force Time History Decomposition
In order to study the two components of the
horizontal and vertical wave forces separately, the
high-frequency slamming component and the low-
frequency quasi-static force component are
extracted from the original measurement using a
10th ordered Daubechie Wavelet method.
Figure 4. Wave force time histories decomposition using a wavelet transform method
Figure 7. Computational domain of the numerical model
Figure 6. Time histories of the total wave forces, quasi-static components
and slamming components of the repeatability test in the vertical direction.
Figure 5. Time histories of the total wave forces, quasi-static components and
slamming components of the repeatability test in the horizontal direction.
0
1000
2000
3000
4000
5000
0.0 0.2 0.4 0.6 0.8
HorizontalQuasi-staticForce(N/m)
Clearance (m)
Fx_qs, H = 0.970 m
Fx_qs, H = 0.680 m
Fx_qs, H = 0517 m
Fx_qs, H = 0.430 m
0
2000
4000
6000
8000
0 0.2 0.4 0.6 0.8
VerticalUpliftQuasi-staticForce
(N/m)
Clearance (m)
Fz_qs, H = 0.970 m
Fz_qs, H = 0.680 m
Fz_qs, H = 0.517 m
Fz_qs, H = 0.430 m
0
1000
2000
3000
4000
5000
0 0.2 0.4 0.6 0.8
HorizontalSlammingForce(N/m)
Clearance (m)
Fx_sl, H = 0.970 m
Fx_sl, H = 0.680 m
Fx_sl, H = 0.517 m
Fx_sl, H = 0.430 m
0
2000
4000
6000
8000
0 0.2 0.4 0.6 0.8
VerticalUpiiftSlammigForce(N/m)
Clearance (m)
Fz_sl, H = 0.970 m
Fz_sl, H = 0.680 m
Fz_sl, H = 0.517 m
Fz_sl, H = 0.430 m
Figure 8. Comparison of time histories between experimental measures
and numerical simulations of horizontal and vertical wave forces.
Figure 9. Maximum of quasi-static and slamming components in the horizontal
and vertical directions vs. the clearance.