Strut-and-tie modelling of reinforced concrete pile caps

OFFSHORE STANDARD DNV-OS-C502 OFFSHORE CONCRETE STRUCTURES

301 The standard is applicable to Design, Construction, Inspection and Maintenance of Offshore Concrete Structures, using concrete as the structural material in the support structure as defiied in 302 below.
302 The standard can be used in the structural design of the following types of support structures:
~ GBS (Gravity Based Structures) offshore concrete structures for oil/gas production
~ GBS structures for oil/gas production with oil storage facility
~ Floating concrete structures for production of oil/gas. The structure may be of any type floating structure, i.e. Tension leg platform (TLP), Column stabilised units and Barge type units
~ Concrete harbours
~ Artificial concrete export/import harbours, either floating or fixed and with storage facilities, allowing transport of articles and goods with small boats to the artificial harbour
for reloading on large sea going vessels. Cargo may be different types or ore or oil/gas
~ Deep water caisson type concrete foundation of bridges
~ Floating foundations for bridges, parking houses or storage buildings.
303 Appendices A to F are appended to the standard. These appendices contain guidelines for the design of Offshore Concrete Structures.
304 Floating Offshore Concrete structures shall be designed with freeboard and intact stability in accordance with DNVOS-
C301. For temporary phases the stability shall be in accordance with DNV Rules for Planning and Execution of Marine Operations.
305 The development and design of new concepts for Offshore Concrete Structures requires a systematic hazard identification process in order to mitigate the risk to an acceptable risk level. Hazard identification is therefore a central tool in this standard in order to identiSl hazards and mitigate these to an acceptable risk level.

OFFSHORE STANDARD DNV-OS-C503 CONCRETE LNG TERMINAL STRUCTURES AND CONTAINMENT SYSTEMS

301 The standard is applicable to LNG Export and Import Terminal Structures using concrete as the structural material in the support structure as defined in 302 and 303 below.
302 LNG Export Terminal Structures LNG export terminals are, by nature, located near the coast and are designed to liquesl the natural gas which will then be loaded onto LNG carriers. An LNG export terminal generally includes: an incoming natural gas metering and receiving station, including in the case of a two phase incoming pipeline, a slug catcher condensate stabilisation and storage gas treatment units in which any acid gases, water, heavier hydrocarbons and, if appropriate, mercury which might be present in the incoming gas are extracted liquefaction units which produce LNG and within which, ethane, propane, commercial butane, heavier hydrocarbons and nitrogen can be extracted. A proportion of the extracted hydrocarbons can be used as refrigerant make up. A liquefaction unit uses very specific equipment such as cryogenic spool-wound or brazed plate-fin exchangers and high-powered turbo compression units. Two refrigerant cycles in cascade are usually employed LNG storage tanks and the relevant loading plants for filling LNG carriers generation andor purchase and distribution of the utilities necessary for the plant to operate (electricity, steam, cooling water, compressed air, nitrogen, fuel gas etc.) general off-site installations, (gas and liquid flare systems, effluent treatment, fiie fighting systems etc.). Most of the gas treating steps can be commonly found in gas treatment plant for the production of sales gas. e.g. acid gas removal, dehydration, hydrocarbon dew point and liquid natural gas (LNG) recovery.
303 LNG Import Terminals
LNG import terminals are designed to receive LNG from LNG carriers, to unload, store and convert it into the gaseous phase for sending it out to the gas network or gas consumers. Thus an LNG receiving terminal provides several essential functions which are:
~ unloading
~ storage
~ LNG recovery and pressurising
~ vaporising
~ gas quality adjustment.
304 Appendices A-D are appended to the standard. These appendices contain guidelines for the design of Terminals in accordance with approach for Land LNG Terminal Structures in accordance with the approach used for the design of Land LNG Terminal Structures modified with the environmental condition of an offshore terminal.
305 The standard is combining the design and construction experience from the fixedfloating offshore structures DNVOS- C502, DNV Rules for Classification of Ships Pt.5 Ch.5, IMO - IGC Code “the International Code for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk” and the experience from design and construction of land based storage tank for LNG as presented in EN-1473 andNFPA 59A.
306 For the detailed design of primary steel containment tanks reference is made to Rules for Classification of Ships Part 5 Chapter 5, IGC- IMO Code, EN-1473 and NFPA 59A. See Appendices C “General Design Principles LNG Containment Structures” and D “Detailed Structural Design of Containment System” for Guidelines for the design of the primary steel containment tanks in accordance with conventional tanks at land. The environmental impact on offshore terminals are included in these guidelines.
307 On ships, the IGC-IMO type B independent tanks are widely used. These tanks are designed, constructed and inspected in accordance with the requirements in the IGC - IMO Code. The DNV Rules for Classification of Ships Part 5 Section 5 gives detailed requirements for the design of Independent tanks Type B. Site specific data shall be considered in the design of Terminal Structures and Containment Systems.
308 The development and design of new concepts for LNG terminals requires a systematic hazard identification process in order to mitigate the risk to an acceptable risk level. Hazard
identification is therefore a central tool in this standard in order to identiSl hazards and mitigate these to an acceptable risk level.

OFFSHORE STANDARD DNV-OS-C105 STRUCTURAL DESIGN OF TLPS (LRFD METHOD)

301 A TLP is usually applied for drilling, production and export of hydrocarbons. Storage may also be a TLP function.
302 A TLP may be designed to function in different modes, typically operation and survival. Also horizontal movement (e.g. by use of catenary or taut mooring) of TLP above wells may be relevant. Limiting design criteria when going from one mode of operation to another shall be established.
303 The TLP unit should also be designed for transit relocation, if relevant.
304 For novel designs, or unproved applications of designs where limited, or no direct experience exists, relevant analyses and model testing shall be performed which clearly demonstrate that an acceptable level of safety can be obtained, i.e. safety level is not inferior to that obtained when applying this standard to traditional designs.
305 Requirements concerning riser systems are given in DNV-OS-F201.
306 In case of application of a catenary or taut mooring system in combination with tendons, reference is made to DNVOS-E301.
307 Requirements related to stability (intact and damaged) are given in Sec.6 for ULS condition and Sec.8 for ALS condition.

BS EN 13747:2005 Precast concrete products — Floor plates for floor systems

This European standard deals with the requirements, the basic performance criteria and evaluation of conformity for precast floor plates made of reinforced or prestressed normal weight concrete according to EN 1992-1-1:2004, used in conjunction with cast-in-situ concrete (topping) for the construction of composite floor slabs. Annex B gives different types of composite slabs made with floor plates. These floor plates, with or without void formers, can include lattice girders or stiffening ribs incorporated during the precasting. They shall be manufactured in factories by casting, slip forming or extrusion. The products covered by this standard are intended to be used as part of structural floors in applications such as:
- floors and roofs of buildings (including industrial and storage buildings, public buildings as schools, hospitals, etc.);
- parking/circulation areas;
- cover for culverts;
- etc.
The products may be used in seismic areas provided they fulfil the requirements specific to this use.
This standard does not cover:
- reinforced floor plates with a nominal thickness less than 40 mm;
- prestressed floor plates with a nominal thickness less than 50 mm;
- floor plates with a very smooth upper face, such as defined in 6.2.5 of EN 1992-1-1:2004.