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DNV-OS-C502 Offshore Concrete Structures
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Sec.1
C. Definitions
Sec.1
C 100 Verbal forms
Sec.1 C
101 Shall: Indicates a
mandatory requirement to be followed for fulfilment or compliance
with the present standard. Deviations are not permitted unless formally
and rigorously justified, and accepted by all relevant contracting
parties.
Sec.1 C
102 Should: Indicates a
recommendation that a certain course of action is preferred or particularly
suitable. Alternative courses of action are allowable under the
standard where agreed between contracting parties but shall be justified
and documented.
Sec.1 C
103 May: Indicates a permission,
or an option, which is permitted as part of conformance with the
standard.Sec.1
C 200 Terms
Sec.1 C
201 Accidental Limit States (ALS): Ensures
that the structure resists accidental loads and maintain integrity
and performance of the structure due to local damage or flooding.
Sec.1 C
202 Accidental Loads (A): Rare
occurrences of extreme environmental loads, fire, flooding, explosions,
dropped objects, collisions, unintended pressure differences, leakage
of LNG etc.
Sec.1 C
203 Aggregates are the
main ingredient both with respect to volume and weight in a structural
concrete mix.
Sec.1 C
204 Air Gap: Free distance
between the 100 year design wave and the underside of a topside
structure supported on column supports allowing the wave to pass
under the topside structure. When air gap is sufficiently large,
then no wave pressure is applied to the topside structure.
Sec.1 C
205 AS-BUILT Documentation: Documentation
of the offshore Structure as finally constructed. Includes design
basis/design brief documents, updated designed calculations, updated
construction drawings, construction records and approved deviations
reports.
Sec.1 C
206 Atmospheric zone: The
external surfaces of the unit above the splash zone.
Sec.1 C
207 Cathodic protection: A
technique to prevent corrosion of a steel surface by making the
surface to be the cathode of an electrochemical cell.
Sec.1 C
208 Cement is the binder
component in a structural concrete mix
Sec.1 C
209 Characteristic load: The
reference value of a load to be used in the determination of load
effects. The characteristic load is normally based upon a defined
fractile in the upper end of the distribution function for load.
Sec.1 C
210 Characteristic resistance: The
reference value of structural strength to be used in the determination
of the design strength. The characteristic resistance is normally
based upon a 5% fractile in the lower end of the distribution
function for resistance.
Sec.1 C
211 Characteristic material strength: The
nominal value of material strength to be used in the determination
of the design resistance. The characteristic material strength is
normally based upon a 5% fractile in the lower end of the
distribution function for material strength.
Sec.1 C
212 Characteristic value: The
representative value associated with a prescribed probability of
not being unfavourably exceeded during some reference period.
Sec.1 C
213 Classification Note: The
Classification Notes cover proven technology and solutions which
is found to represent good practice by DNV, and which represent
one alternative for satisfying the requirements stipulated in the
DNV Rules or other codes and standards cited by DNV. The classification notes
will in the same manner be applicable for fulfilling the requirements
in the DNV offshore standards.
Sec.1 C
214 Coating: Metallic,
inorganic or organic material applied to steel surfaces for prevention
of corrosion.
Sec.1 C
215 Concrete Grade: A parameter
used to define the concrete strength. Concrete Grade for different
characteristic values of concrete strength is provided in Sec.6 Table C1.
Sec.1 C
216 Corrosion allowance: Extra
wall thickness added during design to compensate for any anticipated
reduction in thickness during the operation.
Sec.1 C
217 Cryogenic Temperature: The
temperature of the stored LNG.
Sec.1 C
218 Deck mating: The operation
when the deck floated on barges are mated with the concrete support
structure.
Sec.1 C
219 Deformation loads (D): Loads
effects on the Terminal caused by termal effects, prestressing effects,
creep/shrinkage effects, differential settlements/deformations
etc.
Sec.1 C
220 Design Hazards: Hazards,
which based on risk assessment is likely to occur. The Design Hazards
are mitigated into the structural design of the Terminal.
Sec.1 C
221 Design brief: An agreed
document where owners requirements in excess of this standard should
be given.
Sec.1 C
222 Design temperature: The
design temperature for a unit is the reference temperature for assessing
areas where the unit can be transported, installed and operated.
The design temperature is to be lower or equal to the lowest daily mean temperature in
air for the relevant areas. For seasonal restricted operations the lowest daily mean temperature in
air for the season may be applied. The cargo temperature shall be
taken into account in the determination of the cargo temperature.
Sec.1 C
223 Design value: The value
to be used in the deterministic design procedure, i.e. characteristic
value modified by the resistance factor or load factor.
Sec.1 C
224 Driving voltage: The
difference between closed circuit anode potential and the protection
potential.
Sec.1 C
225 Ductility: The property
of a steel or concrete member to sustain large deformations without
failure.
Sec.1 C
226 Ductility level Earthquake (DLE): The
ductility level earthquake is defined probabilistically as an earthquake
producing ground motion with a mean recurrence as a minimum of 10
000 years.
Sec.1 C
227 Environmental Loads (E): Loads
from wind, wave, tide, current, snow, ice and earthquake.
Sec.1 C
228 Expected loads and response history: Expected
load and response history for a specified time period, taking into account
the number of load cycles and the resulting load levels and response
for each cycle.
Sec.1 C
229 Expected value: The
most probable value of a load during a specified time period.
Sec.1 C
230 Fatigue: Degradation
of the material caused by cyclic loading.
Sec.1 C
231 Fatigue critical: Structure
with calculated fatigue life near the design fatigue life.
Sec.1 C
232 Fatigue Limit States (FLS): Related
to the possibility of failure due to the effect of cyclic loading.
Sec.1 C
233 Functional Loads: Permanent
(G) and variable loads (Q), except environmental loads (E), to which
the structure can be exposed.
Sec.1 C
234 Grout is a cementitious
material and includes the constituent materials; cement, water and
admixture. Appropriate aggregates may be included
Sec.1 C
235 Guidance note: Information
in the standards in order to increase the understanding of the requirements.
Sec.1 C
236 Hazards Identification: A
list of critical elements, if failed, will have the potential to
cause, or contribute substantially to, a major accident. The list
is based on consequence of failure only, not on likelihood for failure
of the individual hazards.
Sec.1 C
237 High Strength Concrete: A concrete
of Grade in excess of C65.
Sec.1 C
238 Hindcasting: A method
using registered meteorological data to reproduce environmental
parameters. Mostly used for reproducing wave parameters.
Sec.1 C
239 Inspection: Activities
such as measuring, examination, testing, gauging one or more characteristics
of an object or service and comparing the results with specified
requirements to determine conformity.
Sec.1 C
240 Light Weight Aggregate Concrete
(LWA): A concrete made with lightweight aggregates conforming
to requirements contained in recognized standards, e.g. relevant
ASTM, ACI or EN standard.
Sec.1 C
241 Limit State: A state
beyond which the structure no longer satisfies the requirements.
The following categories of limit states are of relevance for structures:ULS = ultimate
limit statesFLS = fatigue limit statesALS = accidental limit statesSLS = serviceability limit states.
Sec.1 C
242 Limit State Design: Design
of the Offshore Concrete Structure in the limit states of ULS, SLS,
FLS and ALS.
Sec.1 C
243 Load and Resistance Factor Design
(LRFD): Method for design where uncertainties in loads
are represented with a load factor and uncertainties in resistance
are represented with a material factor.
Sec.1 C
244 Load effect: Effect
of a single design load or combination of loads on the equipment
or system, such as stress, strain, deformation, displacement, motion,
etc.
Sec.1 C
245 Lowest daily mean temperature: The
lowest value on the annual mean daily average temperature curve
for the area in question. For temporary phases or restricted operations,
the lowest daily mean temperature may be defined for specific seasons.Mean
daily average temperature: the statistical mean average
temperature for a specific calendar day.Mean: statistical
mean based on number of years of observations.Average: average
during one day and night.
Sec.1 C
246 Lowest waterline: Typical
light ballast waterline for ships, transit waterline or inspection
waterline for other types of units.
Sec.1 C
247 Mill certificate: A document
made by the Manufacturer of cement which contains the results of
all the required tests and which certifies that the tests have been
carried out by the Manufacturer on samples taken from the delivered
cement themselves.
Sec.1 C
248 Mildly aggressive environment (LA): Indoor
structures in dry climate without aggressiveness
Sec.1 C
249 Moderately aggressive environment
(NA): outdoor structures or indoor structures in humid
environment and structures in fresh water
Sec.1 C
250 Non-cementitious materials
are defined within the context of this Standard as materials such
as epoxy and polyurethane which are specially made for use together
with structural concrete either to improve the concrete properties
or to supplement, repair or replace the concrete.
Sec.1 C
251 Non-destructive testing (NDT): Structural
tests and inspection of welds with radiography, ultrasonic or magnetic powder
methods.
Sec.1 C
252 Normal Strength Concrete: A concrete
of Grade C30 to C65. The Concrete Grade is derived from the characteristic cylinder
strength of concrete in accordance with Sec.6
Table C1.
Sec.1 C
253 Object Standard: The
standards listed in Table B2.
Sec.1 C
254 Offshore Standard: The
DNV offshore standards are documents which presents the principles
and technical requirements for design of offshore structures. The
standards are offered as DNV's interpretation of engineering
practice for general use by the offshore industry for achieving
safe structures.
Sec.1 C
255 Offshore installation: A
general term for mobile and fixed structures, including facilities,
which are intended for exploration, drilling, production, processing
or storage of hydrocarbons or other related activities or fluids.
The term includes installations intended for accommodation of personnel
engaged in these activities. Offshore installation covers subsea
installations and pipelines. The term does not cover traditional
shuttle tankers, supply boats and other support vessels which are
not directly engaged in the activities described above.
Sec.1 C
256 Operating conditions: Conditions
wherein a unit is on location for purposes of production, drilling
or other similar operations, and combined environmental and operational
loadings are within the appropriate design limits established for such
operations (including normal operations, survival, accidental).
Sec.1 C
257 Partial Load Factor: The
specified characteristic permanent, variable, deformation, environmental
or accidental loads are modified with a load factor. This load factor
is part of the safety approach and varies in magnitude for the different load
categories dependent on the individual uncertainties in the characteristic
loads.
Sec.1 C
258 Permanent Functional Loads (G): Self-weight,
ballast weight, weight of permanent installed part of mechanical
outfitting, external hydrostatic pressure, prestressing force etc.
Sec.1 C
259 Potential: The voltage
between a submerged metal surface and a reference electrode.
Sec.1 C
260 Prestressing systems: Tendons
(wires, strands, bars), anchorage devices, couplers and ducts or
sheaths are part of a prestressing system.
Sec.1 C
261 Quality Plan: A plan
implemented to ensure quality in the design, construction and in-service
inspection/maintenance. An interface manual shall be developed
defining all interfaces between the various parties and disciplines
involved to ensure that the responsibilities, reporting routines
and information routines are established.
Sec.1 C
262 Recommended Practice (RP): The
recommended practice publications cover proven technology and solutions
which have been found by DNV to represent good practice, and which
represent one alternative for satisfy the requirements stipulated
in the DNV offshore standards or other codes and standards cited
by DNV.
Sec.1 C
263 Reinforcement is defined
as the constituents of structural concrete providing the tensile
strength that will give the concrete its ductile characteristics.
In these Rules reinforcement is categorised as:| — | ordinary reinforcement |
| — | prestressing reinforcement |
| — | special reinforcement. |
Sec.1 C
264 Robustness: A robust
structure is a structure with low sensitivity to local changes in
geometry and loads.
Sec.1 C
265 Redundancy: The ability
of a component or system to maintain or restore its function when
a failure of a member or connection has occurred. Redundancy may
be achieved for instance by strengthening or introducing alternative
load paths
Sec.1 C
266 Reference electrode: Electrode
with stable open-circuit potential used as reference for potential
measurements.
Sec.1 C
267 Reliability: The ability
of a component or a system to perform its required function without
failure during a specified time interval.
Sec.1 C
268 Repair Materials: Material
used to structurally repair the Offshore Concrete Structure.
Sec.1 C
269 Risk: The qualitative
or quantitative likelihood of an accidental or unplanned event occurring
considered in conjunction with the potential consequences of such
a failure. In quantitative terms, risk is the quantified probability
of a defined failure mode times its quantified consequence.
Sec.1 C
270 Service temperature: Service
temperature is a reference temperature on various structural parts
of the unit used as a criterion for the selection of steel grades
or design for crackwidth etc. in SLS.
Sec.1 C
271 Serviceability Limit States (SLS): Corresponding
to the criteria applicable to normal use or durability.
Sec.1 C
272 Sheaths: Ducts for
post-tensioning tendons. Sheaths shall in general be of a semi rigid
or rigid type, water tight and with adequate stiffness to prevent
damages and deformations.
Sec.1 C
273 Slamming: Impact load
on an approximately horizontal member from a rising water surface
as a wave passes. The direction of the impact load is mainly vertical.
Slamming can also occur within tanks due to stored liquids.
Sec.1 C
274 Specified Minimum Yield Strength
(SMYS): The minimum yield strength prescribed by the
specification or standard under which the material is purchased.
Sec.1 C
275 Specially aggressive environment
(SA): Structures exposed to strong chemical attack which
will require additional protective measures. This may require specially
mixed concrete, membranes or similar.
Sec.1 C
276 Specified value: Minimum
or maximum value during the period considered. This value may take
into account operational requirements, limitations and measures
taken such that the required safety level is obtained.
Sec.1 C
277 Severely aggressive environment
(MA): Structures in saline water, in the splash zone
or exposed to sea spray, structures exposed to aggressive gases,
salt or other chemical substances, and structures exposed to repeated
freezing and thawing in a wet condition
Sec.1 C
278 Splash zone: The external
surfaces of the unit that are periodically in and out of the water.
The determination of the splash zone includes evaluation of all
relevant effects including influence of waves, tidal variations,
settlements, subsidence and vertical motions.
Sec.1 C
279 Stability: The ability
of the floating structure to remain upright and floating when exposed
to small changes in applied loads. The ability of a structural member to carry small additional loads
without buckling.
Sec.1 C
280 Strength level Earthquake (SLE): The
strength level earthquake is defined probabilistically as an earthquake
producing ground motion with a mean recurrence at a minimum interval
of 100 years.
Sec.1 C
281 Structural concrete is
defined as a cementitious composite material and is the main ingredient
for construction of concrete structures.
Sec.1 C
282 Submerged zone: The
part of the unit which is below the splash zone, including buried
parts.
Sec.1 C
283 Survival condition: A
condition during which a unit may be subjected to the most severe
environmental loadings for which the unit is designed. Drilling
or similar operations may have been discontinued due to the severity
of the environmental loadings. The unit may be either afloat or
supported on the sea bed, as applicable.
Sec.1 C
284 Target safety level: A
nominal acceptable probability of structural failure.
Sec.1 C
285 Temporary conditions: Design
conditions not covered by operating conditions,
e.g. conditions during fabrication, mating and installation phases,
transit phases, accidental
Sec.1 C
286 Temporary Phase: Reference
is made fabrication, mating, transit/towing and installation
phases.
Sec.1 C
287 Test report: A document
made by the Manufacturer which contains the results of control tests
on current production, carried out on products having the same method
of manufacture as the consignment, but not necessarily from the delivered
products themselves.
Sec.1 C
288 Tensile strength: Minimum
stress level where strain hardening is at maximum or at rupture
for steel. For concrete it is the direct tensile strength of concrete.
Sec.1 C
289 Transit conditions: All
unit movements from one geographical location to another.
Sec.1 C
290 Ultimate Limit States (ULS): Corresponding
to the maximum load carrying resistance.
Sec.1 C
291 Unit: is a general
term for an offshore structure.
Sec.1 C
292 Utilisation factor: The
fraction of anode material that can be utilised for design purposes.
For design of Terminal structures, the utilisation factor also means
the ratio of used strength to failure strength of concrete, reinforcement
or prestressing steel.
Sec.1 C
293 Variable Functional Loads (Q): Weight
and loads caused by the normal operation of the Offshore Structure.
Variable Functional Loads may vary in position, magnitude and direction
during the operational period and includes modules, gas weight,
stored goods, pressure of stored components, pressures from stored
LNG, temperature of LNG, loads occurring during installation, operational
boat impacts, mooring loads etc.
Sec.1 C
294 Verification: Examination
to confirm that an activity, a product or a service is in accordance
with specified requirements.
Sec.1 C
295 Works' certificate: A document
made by the Manufacturer which contains the results of all the required
tests and which certifies that the tests have been carried out by
the Manufacturer on samples taken from the delivered products themselves.
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