EN ISO 19905-1:2016

SLOVENSKI STANDARD
01-april-2016
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SIST EN ISO 19905-1:2012
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Petroleum and natural gas industries - Site-specific assessment of mobile offshore units -
Part 1: Jack-ups (ISO 19905-1:2016)
Erdöl- und Erdgasindustrie - Beurteilung von mobilen Offshore Einheiten bezüglich ihres
Einsatzgebietes - Teil 1: Hubinseln (ISO/FDIS 19905-1:2015)
Industries du pétrole et du gaz naturel - Évaluation spécifique au site d'unités mobiles en
mer - Partie 1: Plates-formes auto-élévatrices (ISO 19905-1:2016)
Ta slovenski standard je istoveten z: EN ISO 19905-1:2016
ICS:
75.180.10 Oprema za raziskovanje in Exploratory and extraction
odkopavanje equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 19905-1
EUROPEAN STANDARD
NORME EUROPÉENNE
February 2016
EUROPÄISCHE NORM
ICS 75.180.10 Supersedes EN ISO 19905-1:2012
English Version
Petroleum and natural gas industries - Site-specific
assessment of mobile offshore units - Part 1: Jack-ups (ISO
19905-1:2016)
Industries du pétrole et du gaz naturel - Évaluation Erdöl- und Erdgasindustrie - Beurteilung von mobilen
spécifique au site d'unités mobiles en mer - Partie 1: Offshore Einheiten bezüglich ihres Einsatzgebietes -
Plates-formes auto-élévatrices (ISO 19905-1:2016) Teil 1: Hubinseln (ISO 19905-1:2016)
This European Standard was approved by CEN on 2 January 2016.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2016 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 19905-1:2016 E
worldwide for CEN national Members.

Contents Page
European Foreword . 3
European Foreword
This document (EN ISO 19905-1:2016) has been prepared by Technical Committee ISO/TC 67
"Materials, equipment and offshore structures for petroleum, petrochemical and natural gas industries"
in collaboration with Technical Committee CEN/TC 12 “Materials, equipment and offshore structures
for petroleum, petrochemical and natural gas industries” the secretariat of which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by August 2016, and conflicting national standards shall
be withdrawn at the latest by August 2016.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent
rights.
This document supersedes EN ISO 19905-1:2012.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia,
Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands,
Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 19905-1:2016 has been approved by CEN as EN ISO 19905-1:2016 without any
modification.
INTERNATIONAL ISO
STANDARD 19905-1
Second edition
2016-01-15
Petroleum and natural gas
industries — Site-specific assessment
of mobile offshore units —
Part 1:
Jack-ups
Industries du pétrole et du gaz naturel — Évaluation spécifique au
site d’unités mobiles en mer —
Partie 1: Plates-formes auto-élévatrices
Reference number
ISO 19905-1:2016(E)
©
ISO 2016
ISO 19905-1:2016(E)
© ISO 2016, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2016 – All rights reserved

ISO 19905-1:2016(E)
Contents Page
Foreword . v
Introduction . vii
1 Scope . 1
2 Normative references . 2
3 Terms and definitions . 2
4 Symbols and abbreviated terms . 13
4.1 Symbols . 13
4.2 Abbreviated terms . 15
5 Overall considerations . 16
5.1 General . 16
5.2 Assessment approach . 16
5.3 Selection of limit states . 19
5.4 Determination of assessment situations . 20
5.5 Exposure levels . 21
5.6 Analytical tools . 25
6 Data to assemble for each site . 25
6.1 Applicability . 25
6.2 Jack-up data . 25
6.3 Site and operational data. 25
6.4 Metocean data . 26
6.5 Geophysical and geotechnical data . 27
6.6 Earthquake data . 27
7 Actions . 27
7.1 Applicability . 27
7.2 General . 28
7.3 Metocean actions . 28
7.4 Functional actions . 29
7.5 Displacement dependent effects . 29
7.6 Dynamic effects . 29
7.7 Earthquakes . 29
7.8 Other actions . 29
8 Structural modelling . 30
8.1 Applicability . 30
8.2 Overall considerations . 30
8.3 Modelling the leg . 31
8.4 Modelling the hull . 31
8.5 Modelling the leg-to-hull connection . 32
8.6 Modelling the spudcan and foundation . 32
8.7 Mass modelling . 33
8.8 Application of actions . 34
9 Foundations . 37
9.1 Applicability . 37
9.2 General . 37
9.3 Geotechnical analysis of independent leg foundations . 37
9.4 Other considerations . 41
© ISO 2016 – All rights reserved iii

ISO 19905-1:2016(E)
10 Structural response . 43
10.1 Applicability . 43
10.2 General considerations . 43
10.3 Types of analyses and associated methods . 43
10.4 Common parameters . 44
10.5 Storm analysis . 46
10.6 Fatigue analysis . 48
10.7 Earthquake analysis . 48
10.8 Accidental situations . 49
10.9 Alternative analysis methods . 49
11 Long-term applications . 50
11.1 Applicability . 50
11.2 Assessment data . 50
11.3 Special requirements . 51
11.4 Survey requirements . 51
12 Structural strength . 52
12.1 Applicability . 52
12.2 Classification of member cross-sections . 53
12.3 Section properties of non-circular prismatic members . 54
12.4 Effects of axial force on bending moment . 55
12.5 Strength of tubular members . 55
12.6 Strength of non-circular prismatic members . 55
12.7 Assessment of joints . 55
13 Acceptance criteria . 55
13.1 Applicability . 55
13.2 General formulation of the assessment check . 56
13.3 Leg strength assessment . 57
13.4 Spudcan strength assessment. 57
13.5 Holding system strength assessment . 57
13.6 Hull elevation assessment . 58
13.7 Leg length reserve assessment . 58
13.8 Overturning stability assessment . 58
13.9 Foundation integrity assessment . 59
13.10 Interaction with adjacent infrastructure . 60
13.11 Temperatures . 60
Annex A (informative) Additional information and guidance . 61
Annex B (normative) Summary of partial action and partial resistance factors . 249
Annex C (informative) Additional information on structural modelling and response analysis . 251
Annex D (informative) Foundations — Recommendations for the acquisition of site-specific
geotechnical data . 261
Annex E (informative) Foundations — Additional information and alternative approaches . 267
Annex F (informative) Informative annex on Clause A.12 — Structural strength . 280
Annex G (informative) Contents list for typical site-specific assessment report . 295
Annex H (informative) Regional information . 302
Bibliography . 311

iv © ISO 2016 – All rights reserved

ISO 19905-1:2016(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national
standards bodies (ISO member bodies). The work of preparing International Standards is normally
carried out through ISO technical committees. Each member body interested in a subject for which a
technical committee has been established has the right to be represented on that committee.
International organizations, governmental and non‐governmental, in liaison with ISO, also take part in
the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all
matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO's adherence to the WTO principles in the Technical
Barriers to Trade (TBT) see the following URL: Foreword ‐ Supplementary information
The committee responsible for this document is ISO/TC 67, Materials, equipment and offshore structures for
petroleum, petrochemical and natural gas industries, Subcommittee SC 7, Offshore structures.
This second edition cancels and replaces the first edition (ISO 19905‐1:2012), which has been technically revised.
ISO 19905 consists of the following parts, under the general title Petroleum and natural gas industries — Site-
specific assessment of mobile offshore units:
 Part 1: Jack-ups
 Part 2: Jack-ups commentary and detailed sample calculation [Technical Report]
The following parts are under preparation:
 Part 3: Floating units
ISO 19905 is one of a series of International Standards for offshore structures. The full series comprises the
following:
 ISO 19900, Petroleum and natural gas industries — General requirements for offshore structures
 ISO 19901 (all parts), Petroleum and natural gas industries — Specific requirements for offshore structures
© ISO 2016 – All rights reserved v

ISO 19905-1:2016(E)
 ISO 19902, Petroleum and natural gas industries — Fixed steel offshore structures
 ISO 19903, Petroleum and natural gas industries — Fixed concrete offshore structures
 ISO 19904‐1, Petroleum and natural gas industries — Floating offshore structures — Part 1: Monohulls, semi-
submersibles and spars
 ISO/TR 19905‐2, Petroleum and natural gas industries — Site-specific assessment of mobile offshore units —
Part 2: Jack-ups commentary and detailed sample calculation
 ISO 19905‐3, Petroleum and natural gas industries — Site-specific assessment of mobile offshore units — Part 3:
Floating units
 ISO 19906, Petroleum and natural gas industries — Arctic offshore structures
vi © ISO 2016 – All rights reserved

ISO 19905-1:2016(E)
Introduction
The series of International Standards applicable to types of offshore structure, ISO 19900 to ISO 19906, addresses
design requirements and assessments for all offshore structures used by the petroleum and natural gas industries
worldwide. Through their application, the intention is to achieve reliability levels appropriate for manned and
unmanned offshore structures, whatever the type of structure and the nature or combination of the materials
used.
It is important to recognize that structural integrity is an overall concept comprising models for describing
actions, structural analyses, design or assessment rules, safety elements, workmanship, quality control procedures
and national requirements, all of which are mutually dependent. The modification of one aspect of design or
assessment in isolation can disturb the balance of reliability inherent in the overall concept or structural system.
The implications involved in modifications, therefore, need to be considered in relation to the overall reliability of
offshore structural systems.
The series of International Standards applicable to types of offshore structure is intended to provide a wide
latitude in the choice of structural configurations, materials and techniques, without hindering innovation. Sound
engineering judgement is therefore necessary in the use of these International Standards.
This part of ISO 19905, which has been developed from the Society of Naval Architects and Marine Engineers
(SNAME) Technical & Research Bulletin 5‐5A (2002), states the general principles and basic requirements for the
site‐specific assessment of mobile jack‐ups; it is intended to be used for assessment and not for design.
NOTE For the exposure level 1(L1) assessment and, where appropriate, the exposure level 2 (L2) assessment prior to
evacuation being effected, this part of ISO 19905 requires the use of 50 year independent or 100 year joint probability
metocean extremes, together with associated partial action factors. It is based on extensive benchmarking and best practice in
the international community.
Site‐specific assessment is normally carried out when an existing jack‐up unit is to be installed at a specific site.
The assessment is not intended to provide a full evaluation of the jack‐up; it assumes that aspects not addressed
herein have been addressed using other practices and standards at the design stage. In some instances, the
original design of all or part of the structure could be in accordance with other standards in the ISO 19900 series,
and in some cases, different practices or standards could have been applied.
The purpose of the site assessment is to demonstrate the adequacy of the jack‐up and its foundations for the
assessment situations and defined limit states, taking into account the consequences of failure. It is important that
the results of a site‐specific assessment be appropriately recorded and communicated to those persons required
to know or act on the conclusions and recommendations. Alternative approaches to the site‐specific assessment
can be used, provided that they have been shown to give a level of structural reliability equivalent, or superior, to
that implicit in this part of ISO 19905.
Annex A provides background to and guidance on the use of this part of ISO 19905. The clause numbering in
Annex A is the same as in the normative text in order to facilitate cross‐referencing. ISO/TR 19905‐2 provides
additional background to some clauses and a detailed sample 'go‐by' calculation.
Annex B summarizes the partial factors. Supplementary information is presented in Annexes C to H.
To meet certain needs of industry for linking software to specific elements in this part of ISO 19905, a special
numbering system has been permitted for figures, tables, formulae and bibliographic references.
In International Standards, the following verbal forms are used:
© ISO 2016 – All rights reserved vii

ISO 19905-1:2016(E)
 “shall” and “shall not” are used to indicate requirements strictly to be followed in order to conform to the
document and from which no deviation is permitted;
 “should” and “should not” are used to indicate that, among several possibilities, one is recommended as
particularly suitable, without mentioning or excluding others, or that a certain course of action is preferred
but not necessarily required, or that (in the negative form) a certain possibility or course of action is
deprecated but not prohibited;
 “may” is used to indicate a course of action permissible within the limits of the document;
 “can” and “cannot” are used for statements of possibility and capability, whether material, physical or causal.
viii © ISO 2016 – All rights reserved

INTERNATIONAL STANDARD ISO 19905-1:2016(E)

Petroleum and natural gas industries — Site-specific assessment
of mobile offshore units — Part 1: Jack-ups
1 Scope
This part of ISO 19905 specifies requirements and guidance for the site‐specific assessment of independent leg
jack‐up units for use in the petroleum and natural gas industries. It addresses:
a) manned non‐evacuated, manned evacuated and unmanned jack‐ups;
b) the installed phase at a specific site.
To ensure acceptable reliability, the provisions of this part of ISO 19905 form an integrated approach, which is
used in its entirety for the site‐specific assessment of a jack‐up.
This part of ISO 19905 does not apply specifically to mobile offshore drilling units operating in regions subject to
sea ice and icebergs. When assessing a jack‐up operating in such areas, it is intended that the assessor supplement
the provisions of this part of ISO 19905 with the provisions relating to ice actions and procedures for ice
management contained in ISO 19906.
This part of ISO 19905 does not address design, transportation to and from site, or installation and removal from
site. However, it is advisable that the assumptions used in the assessment be checked against the as‐installed
configuration.
To ensure that the design of the jack‐up is sound and the structure is adequately maintained, this part of
ISO 19905 is applicable only to independent leg jack‐ups that either:
 hold a valid classification society certification from a recognized classification society (RCS) throughout the
duration of the operation at the specific site subject to assessment; or
 have been verified by an independent competent body to be structurally fit for purpose for elevated
situations and are subject to periodic inspection, both to the standards of an RCS.
NOTE 1 An RCS is an International Association of Classification Societies (IACS) member body, meeting the RCS definition
given in 3.52.
Jack‐ups that do not comply with this requirement are assessed according to the provisions of ISO 19902,
supplemented by methodologies from this part of ISO 19905, where applicable.
NOTE 2 Future revisions of this part of ISO 19905 can be expanded to cover mat‐supported jack‐ups.
NOTE 3 Well conductors are a safety‐critical element for jack‐up operations. However, the integrity of well conductors is
not part of the site‐specific assessment process for jack‐ups and is, therefore, not addressed in this part of ISO 19905. Annex A
provides references to other publications addressing this topic.
NOTE 4 RCS rules and the IMO MODU code provide guidance for the design of jack‐ups.
© ISO 2016 – All rights reserved
ISO 19905-1:2016(E)
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are indispensable
for its application. For dated references, only the edition cited applies. For undated references, the latest edition of
the referenced document (including any amendments) applies.
ISO 19900, Petroleum and natural gas industries — General requirements for offshore structures
ISO 19901‐1:2015, Petroleum and natural gas industries — Specific requirements for offshore structures — Part 1:
Metocean design and operating conditions
ISO 19901‐2, Petroleum and natural gas industries — Specific requirements for offshore structures — Part 2: Seismic
design procedures and criteria
ISO 19902, Petroleum and natural gas industries — Fixed steel offshore structures
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 19900, ISO 19901‐1, ISO 19901‐2 and
ISO 19902, and the following apply.
NOTE Other terms and definitions relevant for the use of this part of ISO 19905 are found in ISO 19901‐4 and ISO 19906.
3.1
abnormal wave crest
3 4
wave crest with probability of typically 10 to 10 per annum
3.2
accidental situation
exceptional situation of the structure
EXAMPLES Impact, fire, explosion, local failure, loss of intended differential pressure (e.g. buoyancy).
3.3
action
external load applied to the structure (direct action) or an imposed deformation or acceleration (indirect action)
EXAMPLE An imposed deformation can be caused by fabrication tolerances, settlement, temperature change or
moisture variation.
Note 1 to entry: An earthquake typically generates imposed accelerations.
[SOURCE: ISO 19900:2013, 3.3]
3.4
assessment
site-specific assessment
evaluation of the stability and structural integrity of a jack‐up and, where applicable, its seabed restraint or
support against the actions determined in accordance with the requirements of this part of ISO 19905
Note 1 to entry: An assessment can be limited to an evaluation of the components or members of the structure which, when
removed or damaged, could cause failure of the whole structure, or a significant part of it.

To be published. Replaces ISO 19901‐1:2005.
© ISO 2016 – All rights reserved
ISO 19905-1:2016(E)
3.5
assessment situation
jack‐up configuration together with the environmental loading to be assessed
Note 1 to entry: For discussion on configuration, see 5.4.1.
Note 2 to entry: The assessment situations are checked against the acceptance criteria of this part of ISO 19905 to demonstrate
that the relevant limit states are not exceeded.
3.6
assessor
entity performing the site‐specific assessment
3.7
backfill
submerged weight of all of the soil that can be present on top of the spudcan
Note 1 to entry: Backfilling can occur during or after preloading. W refers to the submerged weight of the backfilling that
BF,o
occurs up to achieving the preload reaction. W refers to the submerged weight of the backfilling that occurs after the
BF,A
maximum preload has been applied and held. Both W and W can comprise backflow and/or infill. For discussion of the
BF,o BF,A
effects, see A.9.3.2.1.4.
3.8
backflow
soil that flows from beneath the spudcan around the sides and onto the top
Note 1 to entry: Backflow is part of backfill (3.7).
3.9
basic variable
one of a specified set of variables representing physical quantities which characterize actions, environmental
influences, geometrical quantities, or material properties including soil properties
[SOURCE: ISO 19900:2013, 3.7]
3.10
boundary conditions
actions and constraints on a (section of a) structural component (or a group of structural components) by other
structural components or by the environment surrounding it
Note 1 to entry: Boundary conditions can be used to generate reaction forces at locations of restraint.
[SOURCE: ISO 19902:2007, 3.6]
3.11
chart datum
local datum used to fix water depths on a chart or tidal heights over an area
Note 1 to entry: Chart datum is usually an approximation to the level of the lowest astronomical tide.
[SOURCE: ISO 19901‐1:2015, 3.2]
3.12
consequence category
classification system for identifying the environmental, economic and indirect personnel safety consequences of
failure of a jack‐up
© ISO 2016 – All rights reserved
ISO 19905-1:2016(E)
Note 1 to entry: Categories for environmental and economic consequences are the following (see 5.3.3):
 C1: high environmental or economic consequence;
 C2: medium environmental or economic consequence;
 C3: low environmental or economic consequence.
[SOURCE: ISO 19902:2007, definition 3.11, modified]
3.13
critical component
structural component, failure of which could cause failure of the whole structure, or a significant part of it
Note 1 to entry: A critical component is part of the primary structure.
[SOURCE: ISO 19902:2007, 3.12]
3.14
dynamic amplification factor
DAF
ratio of a dynamic action effect to the corresponding static action effect
Note 1 to entry: For a jack‐up, the dynamic action effect is best simulated by means of a concentrated or distributed inertial
loadset. It is usually not appropriate to factor the static actions to simulate the effects of dynamic actions.
Note 2 to entry: The DAF excluding the mean values, K , can typically be obtained from a single degree‐of‐freedom
DAF,SDOF
(SDOF) calculation. In this case, it is defined as the ratio of the amplitude of a dynamic action effect to the amplitude of the
corresponding static action effect for periodic excitation of a linear one degree‐of‐freedom model approximation of jack‐up
behaviour.
Note 3 to entry: The DAF including the mean values, K , can typically be obtained from a random wave calculation. In
DAF,RANDOM
this case, it is defined as the ratio of the absolute value of a dynamic action effect to the absolute value of the corresponding
static action effect, each including their mean value.
[SOURCE: ISO 19902:2007, definition 3.16, modified]
3.15
deterministic analysis
analysis in which the response is determined from a single combination of actions
3.16
exposure level
classification system used to define the requirements for a structure based on consideration of life‐safety and of
environmental and economic consequences of failure
Note 1 to entry: An exposure level 1 (L1) jack‐up is the most critical and exposure level 3 (L3) the least (see 5.5).
[SOURCE: ISO 19902:2007, definition 3.18, modified]
3.17
extreme storm event
extreme combination of wind, wave and current conditions to which the structure can be subjected during its
deployment
Note 1 to entry: This is the metocean event used for ULS storm assessment (see 5.5.4 and 6.4).
3.18
fixed load
permanent parts of the jack‐up, including hull, legs and spudcans, outfit, stationary and moveable‐fixed equipment
© ISO 2016 – All rights reserved
ISO 19905-1:2016(E)
Note 1 to entry: Moveable‐fixed equipment normally includes the drilling package structure and associated permanently
attached equipment.
3.19
footprint
sea floor depression which remains when a jack‐up is removed from a site
3.20
foundation
soil and spudcan supporting a jack‐up leg
3.21
foundation fixity
rotational restraint offered by the soil to the spudcan
3.22
foundation stability
ability of the foundation to provide sufficient support to remain stable when subjected to actions and incremental
deformation
3.23
global analysis
determination of a consistent set of internal forces and moments, or stresses, in a structure that are in equilibrium
with a defined set of actions on the entire structure
Note 1 to entry: When a global analysis is of a transient situation (e.g. earthquake), the inertial response is part of the
equilibrium.
[SOURCE: ISO 19902:2007, definition 3.23, modified]
3.24
independent leg jack-up
jack‐up unit with legs that can be raised and lowered independently
3.25
inertial loadset
set of actions that approximates the effect of the inertial forces
Note 1 to entry: An inertial loadset is used only in quasi‐static analyses.
3.26
infill
soil above the plan area of the spudcan arising from sediment transport or hole sidewall collapse
Note 1 to entry: Infill is part of backfill (3.7).
3.27
intrinsic wave frequency
wave frequency of a periodic wave in a reference frame that is stationary with respect to the wave
Note 1 to entry: If there is no current, the reference frame is also stationary with respect to the sea floor. If there is a current,
the reference frame moves with the same speed and in the same direction as the current.
3.28
jack-up
mobile offshore unit with a buoyant hull and one or more legs that can be moved up and down relative to the hull
© ISO 2016 – All rights reserved
ISO 19905-1:2016(E)
Note 1 to entry: A jack‐up reaches its operational mode by lowering the leg(s) to the seabed and then raising the hull to the
required elevation. The majority of jack‐ups have three or more legs, each of which can be moved independently and which are
supported in the seabed by spudcans.
3.29
jack-up owner
representative of the companies owning or chartering the jack‐up
3.30
joint probability metocean data
combinations of wind, wave and current that produce the action effect that can be expected to occur at a site, on
average, once in the return period
3.31
leaning instability
instability of an independent leg jack‐up that can arise when the rate of increase of actions on the foundation with
jack‐up inclination exceeds the rate of increase of foundation capacity with depth
3.32
life-safety category
classification system for identifying the applicable level of life‐safety of personnel on a jack‐up
Note 1 to entry: Categories for life‐safety are the following (see 5.5.2):
 S1: manned non‐evacuated;
 S2: manned evacuated;
 S3: unmanned.
[SOURCE: ISO 19902:2007, definition 3.27, modified]
3.33
limit state
state beyond which the structure no longer fulfils the relevant assessment criteria
[SOURCE: ISO 19900:2013, definition 3.28, modified]
3.34
load case
compatible load arrangements, sets of deformations and imperfections considered simultaneously with
permanent actions and fixed variable actions for a particular design or verification
[SOURCE: ISO 19902:2007, 3.29]
3.35
long-term operation
operation of a jack‐up on one particular site for more than the RCS special survey period
3.36
lowest astronomical tide
LAT
level of low tide when all harmonic components causing the tides are in phase
Note 1 to entry: The harmonic components are in phase approximately once every 19 years, but these conditions are
...