1、ACI 357R-84(Reapproved 1997)Guide for the Design and Construction ofFixed Offshore Concrete StructuresReported by ACI Committee 357Harvey H. Haynes, chairmanA. Leon AbolitzArthur R. AndersonJal N. BirdyIrvin BoazAnthony D. BoydWilliam J. CichanskiAssociate MembersNicholas CarinoJohn ClarkeA.E. Fiora
2、to, secretaryGeorge F DavenportJoseph A. DobrowolskiJ.M. DuncanSvein FjeldBen C. Gerwick, Jr.Odd E. GjervEivind HognestadThe report provides a guide for the design and construc-tion of fixed reinforced andlor prestressed concrete struc-tures for service in a marine environment. Only fixed struc-ture
3、s which are founded on the seabed and obtain theirstability from the vertical forces of gravity are covered.Contents include: materials and durability; dead, defor-mation, live, environmental, and accidental loads; designand analysis; foundations; construction and installation;and inspection and rep
4、air. Two appendixes discuss environ-mental loads such as wave, wind, and ice loads in detail, andthe design of offshore concrete structures for earthquakeresistance.Keywords: anchorage (structural); concrete construction; constructionmaterials; cracking (fracturing); dynamic loads; earthquakes; eart
5、hquake re-sistant structures; foundations; grouting; harbor structures; inspection;loads (forces); ocean bottom; offshore structures; post-tensioning; pre-stressed concrete; prestressing steels; reinforced concrete; repairs; staticloads; structural analysis; structural design; underwater constructio
6、n.CONTENTSPreface, page 357R-2Notation, page 357R-2Chapter 1-General, page 357R-21.1 -scope 1.3-Auxiliary systems and1.2-Instrumentation interfacesACI Committee Reports, Guides, Standard Practices, and Commen-taries are intended for guidance in designing, planning, executing, orinspecting constructi
7、on and in preparing specifications. Reference tothese documents shall not be made in the Project Documents. If itemsfound in these documents are desired to be part of the Project Docu-ments, they should be phrased in mandatory language and incorpo-rated into the Project Documents.William A. lngraham
8、 Charles E. SmithRichard W. Litton Raymond J. SmithAlan H. Mattock Stanley G. StiansenKarl H. Runge Alfred A. YeeB.P. Malcolm Sharples Shu-Yin YuMasatane KokubuW. Frank ManningT.H. MonnierChapter 2-Materials and durability, page 357R-32.l-General 2.13-Concrete cover of2.2-Testing reinforcement2.3-Qu
9、ality control 2.14-Details of reinforcement2.4-Durability 2.15-Physical and chemical2.5-Cement damage2.6-Mixing water 2.16-Protection of prestressed2.7-Aggregates anchorages2. g-concrete 2.17-Anchorages for embedments2.9-Admixtures and connections to steel work2.10-Reinforcing and 2.18-Electrical gr
10、oundprestressing steel 2.19-Durability of pipes containing2.11-Post-tensioning ducts pressure2.12-Grout 2.20-Epoxy resinsChapter 3-Loads, page 357R-63.1-Classifications 3.2-Design phasesChapter 4-Design and analysis, page 357R-64.l-General 4.5-Special requirements4.2-Strength 4.6-Other strength requ
11、irements4.3-Serviceability 4.7-Structural analysis4.4-Design conditionsChapter 5-Foundations, page 357R-105.1 -Site investigation 5.3-Scour5.2-Stability of the sea floor 5.4-Design of mat foundationsChapter 6-Construction, installation, andrelocation, page 357R-12Supersedes ACI 357-78 (Reaffirmed 19
12、82).Copyright 0 1984, American Concrete Institute. All rights reserved including rightsof reproduction and use in any form or by any means, including the making of copiesby any photo process, or by any electronic or mechanical device, printed or written ororal, or recording for sound or visual repro
13、duction or for use in any knowledge or re-trieval system or device, unless permission in writing is obtained from the copyrightproprietors.357R-1357R-2ACI COMMITTEE REPORT6.1- General6.2- Buoyancy and floatingstability6.3- Construction joints6.4- Concreting in hot orcold weather6.5- Curing of concre
14、te6.6- Reinforcement6.7- Prestressing tendons,ducts, and grouting6.9- Construction while afloat ortemporarily grounded6.10- Towing6.11- Installation6.12- Construction on site6.13- Connection of adjoiningstructures6.14- Prevention of damagedue to freezing6.15- Relocation6.8- Initial flotationChapter
15、7- lnspectlon and repair, page 357R-167.1- General 7.3- Repair of concrete7.2- Surveys 7.4- Repairs to cracksChapter References, page 357R-178.1- Standards-type referencesAppendix A-Environmental loads,page 357R-18A.1- IntroductionA.2- Wave loadsA.3- Wave diffractionA.4- CurrentsA.5- Design wave ana
16、lysisA.6- Wave responsespectrum analysisA.7- Dynamic response analysisA.8- Wind loadsA.9- Ice loadsA.10- EarthquakesA.11- ReferencesAppendix B-Design for earthquakes,page 357R-19B.1- Introduction B.6- Dynamic analysisB.2- Overall design B.7- Stress analysisprocedure B.8- Failure modesB.3- Seismicity
17、 study B.9- Ductility requirementsB.4- Site response study B.10- Aseismic design detailsB.5- Selection of design B.11- Other factorscriteriaPREFACEConcrete structures have been used in the North Sea andother offshore areas of the world. With the rapid expansion ofknowledge of the behavior of concret
18、e structures in the sea,and discoveries of hydrocarbons off North American shores,there will likely be an increased use of such structures. Thisreport was developed to provide a guide for the design andconstruction of fixed offshore concrete structures. Referenceto the following documents is acknowl
19、edged:API Recommended Practice for Planning, Designing, andConstructing Fixed Offshore Platforms, API RP2A, Ameri-can Petroleum Institute.Recommendations for the Design and Construction ofConcrete Sea Structures, Federation International de laPrecontrainte. Rules for the Design, Construction, and In
20、spection of Off-shore Structures, Det Norske Veritas.Where adequate data were available, specific recommen-dations were made, while in less developed areas particularpoints were indicated for consideration by the designer. Thedesign of offshore structures requires much creativity of thedesigner, and
21、 it is intended that this guide permit and encour-age creativity and usage of continuing research advance-ments in the development of structures that are safe, service-able and economical.NOTATIONA = accidental loadcm= hydrodynamic coefficientD = dead load, diameter of structural memberE = environme
22、ntal loadEC= concrete modulus of elasticityEi= initial modulus of elasticityEo= frequently occurring environmental loadEImu= extreme environmental load4= reinforcing steel modulus of elasticityL = live loadLX= maximum live loadL, = minimum live loadT = deformation loadW/C = water-cement ratiob = sec
23、tion width4= diameter of reinforcing bar:= effective tension zone= stress in concreteP= allowable design stress in concreteL= stress in reinforcing bar= allowable design stress in reinforcing barf= mean tensile strength of concretek= yield stress of reinforcing bars= 28-day strength of concrete (ACI
24、 318)h = section thicknessX = depth of compression zoneYC= material factor for cohesive soilsYf= material factor for friction type soilsYL= load multiplierY,= material factorY IlKY = material factor for concreteYms= material factor for reinforcing barsA*$= increase in tensile stress in prestressing
25、steel withreference to the stress at zero strain in the concretei= strain= wave length0= strength reduction factorCHAPTER 1-GENERAL1.1-ScopeThis report is intended to be used as a guide for the designof fixed reinforced and/or prestressed concrete structures forservice in a marine environment. Only
26、fixed structures whichare founded on the seabed and obtain their stability from thevertical forces of gravity are covered herein. Such structuresmay be floated utilizing their own positive buoyancy duringconstruction and installation, however.This report is not intended to cover maritime structuress
27、uch as jetties or breakwaters, or those which are constructedprimarily as ships or boats. ACI 318 should be used togetherwith this report. Because of the nature of the marine environ-ment, certain recommendations herein override the require-ments of ACI 318.1.2-InstrumentationIn regions of the struc
28、ture or foundation where it is neces-FIXED OFFSHORE CONCRETE STRUCTURES 357R-3sary to actively control conditions to insure an adequate mar-gin of safety for the structure, instrumentation should beprovided to monitor the conditions. Such conditions mightbe fluid level, temperature, soil pore water
29、pressure, etc.Adequate instrumentation should be provided to insureproper installation of the structure.When new concepts and procedures that extend the fron-tier of engineering knowledge are used, instrumentationshould be provided to enable measured behavior to be com-pared with predicted behavior.
30、1.3-Auxiliary systems and interfacesSpecial consideration should be given to planning and de-signing auxiliary nonstructural systems and their interfaceswith a concrete structure.Auxiliary mechanical, electrical, hydraulic, and controlsystems have functional requirements that may have a signifi-cant
31、 impact on structural design. Special auxiliary systemsmay be required for different design phases of an installation,including construction, transportation, installation, opera-tion, and relocation.Unique operating characteristics of auxiliary systemsshould be considered in assessing structural loa
32、d conditions.Suitable provisions should be made for embedments andpenetrations to accommodate auxiliary equipment.CHAPTER 2-MATERIALS AND DURABILITY2.1-GeneralAll materials to be used in the construction of offshoreconcrete structures should have documentation demonstrat-ing previous satisfactory pe
33、rformance under similar site con-ditions or have sufficient backup test data.2.2-Testing2.2.1- Tests of concrete and other materials should be per-formed in accordance with applicable standards of ASTMlisted in the section of ACI 318 on standards cited. Completerecords of these tests should be avail
34、able for inspection dur-ing construction and should be preserved by the owner duringthe life of the structure.2.2.2- Testing in addition to that normally carried out forconcrete Structures, such as splitting or flexural tensile tests,may be necessary to determine compliance with specified du-rabilit
35、y and quality specifications.2.3-Quality control2.3.1- Quality control during construction of the con-crete structure is normally the responsibility of the contrac-tor. Supervision of quality control should be the responsibil-ity of an experienced engineer who should report directly totop management
36、 of the construction firm. The owner mayprovide quality assurance verification independent of theconstruction firm.2.4-Durability2.4.1- Proper ingredients, mix proportioning, construc-tion procedures, and quality control should produce dur-able concrete. Hard, dense aggregates combined with a lowwat
37、er-cement ratio and moist curing have produced concretestructures which have remained in satisfactory condition for40 years or more in a marine environment.2.4.2- The three zones of exposure to be considered onan offshore structure are:(a) The submerged zone, which can be assumed to be con-tinuously
38、 covered by the sea water.(b) The splash zone, the area subject to continuous wettingand drying.(c) The atmospheric zone, the portion of the structureabove the splash zone.2.4.3- Items to be considered in the three zones are:(a) Submerged zone-Chemical deterioration of the con-crete, corrosion of th
39、e reinforcement and hardware, andabrasion of the concrete.(b) Splash zone-Freeze-thaw durability, corrosion of thereinforcement and hardware and the chemical deteriorationof the concrete, and abrasion due to ice.(c) Atmospheric zone-Freeze-thaw durability, corrosionof reinforcement and hardware, and
40、 fire hazards.2.5-Cement2.5.1- Cement should conform to Type I, II, or III port-land cements in accordance with ASTM C 150 and blendedhydraulic cements which meet the requirements of ASTM C595.2.5.2- The tricalcium aluminate content (C3A) shouldnot be less than 4 percent to provide protection for th
41、e rein-forcement. Based on past experience, the maximum tri-calcium aluminate content should generally be 10 percent toobtain concrete that is resistant to sulfate attack. The abovelimits apply to all exposure zones.2.5.3- Where oil storage is expected, a reduction in theamount of tricalcium alumina
42、te (C3A) in the cement may benecessary if the oil contains soluble sulfates. If soluble sul-fides are present in the oil, coatings or high cement contentsshould be considered.2.5.4- Pozzolans conforming to ASTM C 618 may beused provided that tests are made using actual job materials toascertain the
43、relative advantages and disadvantages of theproposed mix with special consideration given to sulfate re-sistance, workability of the mix, and corrosion protectionprovided to the reinforcement.2.6-Mixing water2.6.1.- Water used in mixing concrete should be cleanand free from oils, acids, alkalis, sal
44、ts, organic materials, orother substances that may be deleterious to concrete or rein-forcement. Mixing water should not contain excessiveamounts of chloride ion. (See Section 2.8.6).2.7-Aggregates2.7.1- Aggregates should conform to the requirements ofASTM C 33 or ASTM C 330 wherever applicable.357R
45、-4 ACI COMMITTEE REPORT2.7.2- Marine aggregates may be used when conformingto ASTM C 33 provided that they have been washed by freshwater so that the total chloride and sulfate content of the con-crete mix does not exceed the limits defined in Section 2.8.6.2.8-Concrete2.8.1- Recommended water-cemen
46、t ratios and minimum28-day compressive strengths of concrete for the three ex-posure zones are given in Table 2.1.2.8.2- Measures to minimize cracking in thin sectionsand to prevent excessive thermal stresses in mass concrete arenecessary if more than 700 pounds of cement per cubic yardof concrete a
47、re used (415 kg per cubic meter). A minimumcement content of 600 pounds per cubic yard (356 kg percubic meter) is recommended to obtain high quality paste ad-jacent to the reinforcement for corrosion protection.2.8.3- The rise of temperature in concrete because of ce-ment heat of hydration requires
48、strict control to prevent steeptemperature stress gradients and possible thermal cracking ofthe concrete on subsequent cooling. Reducing the tem-perature rise may be difficult in the rich mixes and thick sec-tions required in concrete sea structures.The control of concrete temperatures includes sele
49、ction ofcements which have low heat of hydration, reduced rates ofplacement, precooling of aggregates, the use of ice to replacesome or all of the mixing water and liquid nitrogen cooling,as described in ACI 207.4R. Pozzolans may be used to re-place a portion of the cement to lower the heat of hydration.2.8.4- When freeze-thaw durability is required, the con-crete should contain entrained air as recommended by Table1.4.3 of ACI 201.2R. Air entrainment is the most effectivemeans of providing freeze-thaw resistance to the cement
