1、ACI 349.1R-07Reinforced Concrete Designfor Thermal Effects onNuclear Power Plant StructuresReported by ACI Committee 349American Concrete InstituteAdvancing concrete knowledgeReinforced Concrete Design for Thermal Effectson Nuclear Power Plant StructuresFirst printingJune 2007ISBN 978-0-87031-246-05
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10、tained by contacting ACI.Most ACI standards and committee reports are gathered together in the annually revised ACI Manual ofConcrete Practice (MCP).American Concrete Institute38800 Country Club DriveFarmington Hills, MI 48331U.S.A.Phone: 248-848-3700Fax: 248-848-3701www.concrete.orgACI 349.1R-07 su
11、persedes ACI 349.1R-91 and was adopted and published May 2007.Copyright 2007, American Concrete Institute.All rights reserved including rights of reproduction and use in any form or by anymeans, including the making of copies by any photo process, or by electronic ormechanical device, printed, writt
12、en, or oral, or recording for sound or visual reproductionor for use in any knowledge or retrieval system or device, unless permission in writingis obtained from the copyright proprietors.349.1R-1ACI Committee Reports, Guides, Standard Practices, andCommentaries are intended for guidance in planning
13、,designing, executing, and inspecting construction. Thisdocument is intended for the use of individuals who arecompetent to evaluate the significance and limitations of itscontent and recommendations and who will acceptresponsibility for the application of the material it contains.The American Concr
14、ete Institute disclaims any and allresponsibility for the stated principles. The Institute shall notbe liable for any loss or damage arising therefrom.Reference to this document shall not be made in contractdocuments. If items found in this document are desired by theArchitect/Engineer to be a part
15、of the contract documents, theyshall be restated in mandatory language for incorporation bythe Architect/Engineer.Reinforced Concrete Design for Thermal Effectson Nuclear Power Plant StructuresReported by ACI Committee 349ACI 349.1R-07This report presents a design-oriented approach for considering t
16、hermaleffect on reinforced concrete structures. Although the approach is intended toconform to the general provisions of Appendix E of ACI 349, it is notrestricted to nuclear power plant structures. The general behavior of structuresunder thermal effects is discussed together with the significant is
17、sues toconsider in reinforcement design. Two types of structuresframes andaxisymmetric shellsare addressed. For frame structures, a rationale isdescribed for determining the extent of component cracking that can beassumed for purposes of obtaining the cracked structure thermal forces andmoments. Sti
18、ffness coefficients and carryover factors are presented in graph-ical form as a function of the extent of component cracking along its lengthand the reinforcement ratio. Fixed-end thermal moments for cracked compo-nents are expressed in terms of these factors for: 1) a temperature gradientacross the
19、 depth of the component; and 2) end displacements due to auniform temperature change along the axes of adjacent components. For theaxisymmetric shells, normalized cracked section thermal moments arepresented in graphical form. These moments are normalized with respect tothe cross-sectional dimension
20、s and the temperature gradient across thesection. The normalized moments are presented as a function of the internalaxial forces and moments acting on the section and the reinforcement ratio.Use of the graphical information is illustrated by examples.Keywords: cracking (fracturing); frames; nuclear
21、power plants; shells;structural analysis; structural design; temperature; thermal effect; thermalgradient; thermal properties.CONTENTSChapter 1Introduction, p. 349.1R-21.1General1.2Thermal effects and structural responses1.3General guidelines1.4Analysis techniques1.5Consideration of thermal effects
22、in analysis1.6Stiffness and deformation effects1.7SummaryChapter 2Notation and definitions, p. 349.1R-52.1Notation2.2DefinitionsChapter 3Frame structures, p. 349.1R-73.1Scope3.2Section cracking3.3Component cracking3.4Cracked component fixed-end moments, stiffnesscoefficients, and carryover factors3.
23、5Frame design exampleOmesh B. Abhat Branko Galunic Charles J. Hookham*Richard S. Orr*Adeola K. Adediran Partha S. Ghosal*Scott A. Jensen*Bozidar StojadinovicHansraj G. Ashar Herman L. Graves, III Jagadish R. Joshi Barendra K. TalukdarRanjit L. Bandyopadhyay Orhan Gurbuz*Richard E. Klingner Donald T.
24、 WardPeter J. Carrato James A. Hammell Nam-Ho Lee Andrew S. WhittakerRonald A. Cook Gunnar A. Harstead*Dan J. Naus*Albert Y. C. WongRolf Eligenhausen Christopher Heinz Dragos A. Nuta Charles A. Zalesiak*Werner A. F. Fuchs*Committee 349 members who were major contributors to the development of this r
25、eport.Ronald J. Janowiak*Chair349.1R-2 ACI COMMITTEE REPORTChapter 4Axisymmetric structures, p. 349.1R-214.1Scope4.2 |e/d| 0.7 for compressive N and tensile N4.3General e/d4.4Design examplesChapter 5References, p. 349.1R-325.1Referenced standards and reports5.2Cited referencesAppendix AExamples in m
26、etric, p. 349.1R-33A.1Frame design example from 3.5A.2Design examples from 4.4CHAPTER 1INTRODUCTION1.1GeneralACI 349, Appendix E, provides general considerations indesigning reinforced concrete structures for nuclear powerplants subject to thermal effects. Thermal effects are definedto be the exposu
27、re of a structure or component thereof tovarying temperature at its surface or temperature gradientthrough its cross section; the resulting response of theexposed structure is a function of its age and moisturecontent, temperature extreme(s), duration of exposure, anddegree of restraint. The terms “
28、force,” “moment,” and“stress” apply and are used in this report where a structure isrestrained against thermally induced movements. Furthertreatment of these forces, moments, and stresses arecontained in this report as a function of type of structure.The Commentary to Appendix E, Section RE.1.2, of
29、ACI349-06 (ACI Committee 349 2006) instructs the designer toconsider the following:1. Linear thermal strain causes stress only under conditionsof restraint, and a portion of such stress may be self-relieving.Mechanisms for relief are: cracking, yielding, relaxation,creep, and other time-dependent de
30、formations; and2. Accident temperature transients may be of such shortduration that the resulting temperature distributions andcorresponding stress changes are not significant. Therefore,these temperature transients may not adversely affect thesafe shutdown capacity of the plant.The Commentary to Ap
31、pendix E, Section RE.3.3, ofACI 349-06 addresses three approaches that considerthermal effects in conjunction with all mechanical loadsacting on the structure. One approach is to consider the structureuncracked under the mechanical loads and cracked under thethermal effects. The results of two such
32、analyses are thencombined.The Commentary to Appendix E also contains a method oftreating temperature distributions across a cracked section.In this method, an equivalent linear temperature distributionis obtained from the temperature distribution, which cangenerally be nonlinear. The linear temperat
33、ure distribution isthen separated into a pure gradient T and into the differencebetween the mean and base (stress-free) temperatures Tm Tb.This report discusses approaches for making an assessmentof thermal effects that are consistent with the aforementionedprovisions. The goal is to present a desig
34、ner-orientedapproach for determining the reduced thermal moments thatresult from cracking of the concrete structure. Thermaleffects should be considered in design for serviceability. Thereport discusses conditions under which it can be shown thatthe thermal effects do not adversely affect the safe s
35、hutdowncapacity of the plant. Behavior and general guidance isaddressed in Chapter 1. Chapter 2 addresses notation anddefinitions. Chapter 3 addresses frame structures, andChapter 4 deals with axisymmetric structures. For framestructures, general criteria are given in Sections 3.2 (Sectioncracking)
36、and 3.3 (Component cracking). The criteria arethen formulated for the moment distribution method ofstructural analysis in Section 3.4. Cracked component fixed-end moments, stiffness coefficients, and carryover factorsare derived and presented in graphical form. For axisymmetricstructures, an approac
37、h is described for regions away fromdiscontinuities, and graphs of cracked section thermalmoments are presented.This report is intended to propose simplifications that maybe used for structural assessments. It will permit exclusion ofthermal cases with small effect and a reduction of thermaleffects
38、for a large class of thermal cases without resorting tosophisticated and complex solutions (Appendix E, 349-06).Also, as a result of the report discussion, the design examples,and graphical presentation of cracked section thermal moments,it is hoped that a designer will better understand how thermal
39、effects are influenced by the presence of other loads and theresulting concrete response, primarily in the form ofcracking, although reinforcement yielding, concrete creep,nonlinear concrete stress-strain, and shrinkage are also verysignificant in mitigating thermal effects in concrete structures.1.
40、2Thermal effects and structural responsesThermal effects cause expansion or contraction of thecomponents in a structural system. If the components arerestrained, which is usually the case, stresses are induced. It issufficient to note that there are three types of thermal effects:1. Bulk temperature
41、 change. In this case, the entire structuralcomponent (or segments of the component) is subject to auniform temperature change;2. Thermal gradient. A temperature crossfall or thermalgradient is caused by different thermal conditions on twofaces of a structure, such as two sides of a wall or the top
42、andbottom of a beam; and3. Local thermal exposure. Elevated temperature at a localsurface caused by an external source such as operatingequipment or piping or an abnormal event such as a fire.Thermal effects will result in different states of stress andstrain in structural components as a function o
43、f restraints.The analysis for thermal effects must distinguish betweendifferent types of thermal effects and properly characterizethe structural response accordingly (for example, the degree offixity of end and boundary restraints, component stiffness,influence of cracking, and concrete and reinforc
44、ing steel strain).Thermal effects can arise from many sources including,but not limited to, process fluid transport; proximity to hotgasses, steam, or water passage (for example, reactor vesselor steam piping from reactor building to turbine); fire; orgradients formed when opposing faces of a struct
45、ure areDESIGN FOR THERMAL EFFECTS ON NUCLEAR POWER PLANT STRUCTURES 349.1R-3exposed to differing temperatures (for example, spent fuelpool) or cyclic gradients from plant startup and shutdown.Temperature change is manifested under one or more of thefollowing transfer mechanisms:1. Radiation. The ele
46、ctromagnetic transfer of heat from ahigher temperature source to a lower temperature surface ofthe concrete structure, such as from a radiator heating a roomand the surrounding wall and floor structures;2. Convection. The transfer of heat usually by the movementof a liquid or gas across a surface, s
47、uch as from environmentaltemperature changes in the air next to a concrete structure; and3. Conduction. The transfer of heat through a solid, suchas from a steam pipeline into the surrounding concrete at apenetration.There are many instances where all three mechanisms arepresent, such as in the case
48、 of a fire acting on a structure.Radiation and convection from the flame itself transfers heatto the impinged structure. The surface of the flame radiatesheat, which is absorbed by the concrete and reinforcing steel;finally, heat is transferred away from the flame-impinged areaby means of conduction
49、 through the structure. The structurewill also lose heat by means of convection and radiation.Response of a structure to thermal effects depends on thenature of the temperature distribution, end constraints, materialproperties, and mechanical loads. A proper thermal stressanalysis must take these parameters into account.Stresses in the concrete and reinforcement occur due torestraint of thermal movement and these stresses are generallyself-relieving. These thermal stresses are generally small, asmost thermal exposures are within prescribed ACI 349tempera
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