Wave Impacts on Structures

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WAVE IMPACTS ON STRUCTURES
CONSTRUCT
R&D
DESIGN Angus Jackson
Executive Engineer, ICM

WAVE FORCES:
W h en w av e s im p a ct a s t r u c t u r e , t h e e n er g y
t r an sf e r i s s u d d e n a nd re p et i t i v e w i t h o nl y a ve ry
s h o r t p e r i o d b et w ee n w a v e s
CONSTRUCT
R&D
DESIGN

WAVE IMPACTS:
N ot j u s t
D ir e c t f o r c e s o n s t r u c t ur e s
A l s o
. Wa v e d r i ve n cu r r e n t s
. S c o u r
. O v e r t o p pi n g
. R u n u p
. S e t u p
. L o n g s h o r e t r a n s po r t
. O n / o f f s h or e t r a n s p o r t
. C o n s t r u c t i o n –m a t e r i a l s , t i m i n g , m e t h o d o l o g y & c o s t
. M a i n t e n a n c e
CONSTRUCT
R&D
DESIGN
WAVES NOT SIMPLE –
IMPACTS COMPLEX &
INTERCONNECTED

IMPORTANCE?
Al m o s t all design s w i l l have w a v e
con d i t i o n s a s a k e y d e s i g n cri t e r i a .
Un d e r - e s t i m a t e
. St r u c t u re fail s or requ i r e s frequ e n t
mai n t e n a n c e
Ov e r - e s t i m a t e
. Hi g h e r cos t
. Hi g h e r impac t s
CONSTRUCT
R&D
DESIGN

WAVE STUDIES
Wav e m o d e l s are now relatively easy and
ge n e r a l l y w a v e m o delling w il l b e c a r r i e d
ou t as a matter of c ourse .
CONSTRUCT
R&D
DESIGN
[Don’t forget other issues!]

WAVE STUDIES
In p u t wave param e t e r s to use in models &
cal c u l a t i o n s such a s ; Hs, Hm, Tp, … … .
CONSTRUCT
R&D
DESIGN
[Real world?, Sensitivity & accuracy??]

DATA
D ee p w a t er w a v e s
CONSTRUCT
R&D
DESIGN
Pierson, ,Hemer, Banner & Pattiaratchi

DATA
D ee p w a t er w a v e s
CONSTRUCT
R&D
DESIGN

STRUCTURES- LOCATION / TYPE
CONSTRUCT
R&D
DESIGN
Breakwaters;
Emerged
Floating
Submerged [reef]
Berths/ Pontoons / Piles
Seawalls
Groynes
Beaches

M O O R I N G S T RU C T U R E S
CONSTRUCT
R&D
DESIGN

WA L L S / OV E RTOP P I N G
CONSTRUCT
R&D
DESIGN

WA L L S / S C O U R
CONSTRUCT
R&D
DESIGN

RU N U P
CONSTRUCT
R&D
DESIGN

RISKS
Risk based design
R i s k o f “ f a i l u r e ” ?
D e f i n e “ f a i l u r e ”
Check sensitivity - depth limited?
Data uncertainty GIGO
Robust design may be best solution?
CONSTRUCT
R&D
DESIGN

COST / BENEFIT
Wave studies are often a significant
design cost.
Given uncertainty, robust design may
be best solution?
Risk?
Check sensitivity - depth limited?
Data uncertainty
CONSTRUCT
R&D
DESIGN

S U M M A RY
Wav e c o n d i t io n s very import a n t for good
de s i g n & efficien t c o n s t ruction
[but not always.]
Wav e stu d i e s relatively easy a n d p r o d u ce
im p r e s s i ve c o l o u r ou t p u t s
[but of selected cases only . - a tool to help to understand the
beast! GIGO]
Ev a l u a t e Risks & Cost / Benefit
CONSTRUCT
R&D
DESIGN

M Y C O M M E N T S
Dea l i n g w i t h a b e a s t !
Ev a l u a t e r i s k s - W he r e h i g h r i s k , b e c a r e f u l
of o v e r - s i m p l i f yi n g an d p l a c i n g t o o mu c h
c o n f i d e n c e o n “ p r e t t y ” w a v e m o d e l s
C on s i d e r C o s t / B e n e f i t
-t o o “ s a f e ” c a n k i l l t h e pr o j e c t
- ro b u s t d es i g n b e s t
-d e f i n e “ f a i l u r e ”?
w w w . c o a s t a l m a n a g m e n t . c o m . a u
CONSTRUCT
R&D
DESIGN