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need for more knowledge about the load from
extreme
waves
unusually high and very irregular
waves
occur more frequently in the north sea than previously assumed. but how often, and how do they impact the platforms?
dhrtc
?s research project
extreme
waves
is seeking answers to these questions. platforms in the north sea are designed to withstand being knocked about a bit. by severe storms and strong currents ? even by
waves
so huge that statisti- cally they should only occur once every 10,000 years. but can the statistics be relied on? and how are the platforms impacted by the
extreme
waves
? ?today, we don?t know enough about
extreme
waves
. we don?t know how fre- quently they occur, we don?t know why they occur, and we don?t know enough about the impact of the
waves
for us to define the degree of uncertainty in relation to the design of offshore struc- tures,? says professor christos ?omas georgakis from the department of engineering at aarhus university.
extreme
waves
are rare, but they happen more frequently than previ- ously assumed. 1 january 1995 is an important date in this context. it was a stormy day ? perhaps a little rougher than usual. around the norwegian platform draupner in the north sea, the sea was so rough that the
waves
measured 12 metres from crest to trough. suddenly, a huge rogue wave measuring 26 metres appeared out of nowhere. ?e wave was not only unusual because of its height. it was also the first time that such an
extreme
wave had ever been accurately detected with measuring equipment. until then, only anecdotal evidence from seafarers existed about objective of the ?
extreme
waves
? project ?
dhrtc
will create an improved load model that can be used by the industry to determine more precisely the loads which off- shore structures are subjected to by
extreme
waves
. the pur- pose is to substantiate the safety of existing structures and to create a basis for more optimum designs in future. ?
dhrtc
is seeking to develop a technology that can measure the wave impact indirectly and in real time by means of sensors. by measuring the response from the platform ? in other words how much it moves ? it will be possible to determine the load from the
waves
. ?
dhrtc
will further develop the analyses of the data coming from the lidar systems ? a combination of laser and radar that regis- ters wave frequency and size. here,
dhrtc
can contribute with the improved collection, processing, and comparison of data that can contribute to modelling
waves
with existing software. 29
dhrtc
2016 demo model ctr3 extend life of platforms to secure infrastructure with a view to ensuring the operation of existing offshore production platforms beyond 2042, the aim of the demonstra- tion model is to demonstrate the ability of permanent structures to withstand impacts from
extreme
waves
. attempts will be made to solve this challenge through a combination of improved monitoring, greater understanding of the physics and frequency of
extreme
waves
, as well as ad- vanced methods for uncertainty handling and risk assessment. to the extent that a prolonged life span can thereby be supported, this opens up for the possibility that existing production facilities can act as nodal points in future tie-in solutions.
dhrtc
?s hypothesis through an improved understanding of structural response and
extreme
waves
, the research hypothesis is to supplement duc?s aware project with a view to reducing the level of uncertainty in the risk analysis, and to thereby enable decisions to be made concerning extended life spans, structural reinforcements, operational initiatives, etc. expected key deliverables ? statistical description of the actual strain. ? wave statistics and monitoring data ? structural monitoring data ? validation of structural calculation models ? load model for and statistical description of
extreme
, breaking
waves
? risk modelling
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