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1、AC1 307-98 Design and Construction of Reinforced Concrete Chimneys (AC1 307-98) Reported by AC1 Committee 307 Victor A. Bochicchio David J. Bird Chairman Secretary John J. Carty Jagadish R. Joshi Randolph W. Snook Brian Cooley Erick N. Larson John C. Sowizal Phillip B. Davidson Robert A. Porthouse B
2、arry J. Vickery Shu-Jin Fang Ronald E. Purkey Chung-Yee John Wei Milton Hartstein Scott D. Richart Edward L. Yordy Thomas Joseph Wadi S. Rumman This standard gives material, construction, and design requirements for cast-in-place and precast reinforced concrete chimneys. It sets forth mini- mum load
3、ings for design and contains methods for determining the con- crete and reinforcement required us a result of these loadings. The method of analysis applies primarily to circular chimney shells; howeveu, a general procedure for analysis of noncircular shapes is included. This standard is written in
4、explicit, mandatory language, and as such, is intended for reference in project speci3cations. Equations are provided for determining the temperature gradient through the concrete resultingfuom the diffrence in temperature of the gases inside the chimney and the surrounding atmosphre. Methods for co
5、mbining the effects of dead and wind (or earthquake) loads with temperature both verti- cally and circumferentially are included in the standard. These methods permit the designer to establish minimum concrete and reinforcement requirements. This standard refers extensively to “Building Code Require
6、ments for Structural Concrete” CI 318); construction requirements are generally in accordance with ACI 318; and notation is in accordance with ACI 104. Keywords: chimneys; compressive strength; concrete construction; earthquake-resistant structures; formwork (construction); foundations; high tempera
7、ture; linings; loads (forces); moments; openings; precast concrete; quality control; reinforced concrete; reinforcing steels; specifications; static loads; strength; structural analysis; structural design; temperature; thermal gradient; wind pressure AC1 Committee Reports, Guides, Standard Practices
8、, and Commentaries are intended for guidance in planning, de- signing, executing, and inspecting construction. This doc- ument is intended for the use of individuals who are competent to evaluate the significance and limitations of its content and recommendations and who will ac- cept responsibility
9、 for the application of the material it contains. The American Concrete Institute disclaims any and all responsibility for the stated principles. The Institute shall not be liable for any loss or damage arising there- from. Reference to this document shall not be made in con- tract documents. If ite
10、ms found in this document are de- sired by the Architect/Engineer to be a part of the contract documents, they shall be restated in mandatory language for incorporation by the Architect/Engineer. CONTENTS p. 3072 1.1-Scope 1.2-Drawings 1.3-Regulations 1 .,“th a, k q.,A; ! l . ,b I - +. 5.1General 5.
11、2-Design Loads 5.3-Required strength 5.LDesign strength 5.5-Nominal moment strength: Circular shells 5.6-Noncircular shapes 5.7-Design for circumferential bending c;$l;qs$ss, p. 3yq2 6.1-General 6.2-Vertical temperature stresses 6.3-Circumferential temperature stresses Testing and Materials referred
12、 to in this standard are listed in the following with their serial designations, including the year of adoption or revision, and are declared to be a part of this standard as if fully set forth here. AC1 104-71 (Revised 1982) (Reapproved 1987) AC1 3 18-95 ASCE 7-95 ASTM A 615-95 ASTM A 617-96 CHAPTE
13、R I-GENERAL 1.1-Scope This standard covers the design and construction of circular cast-in-place or precast reinforced concrete chimney shells. If other shapes are used, their design shall be substan- tiated in accordance with the principles used here. The standard does not include the design of lin
14、ings, but includes the effects of linings on the concrete shell. A precast chimney shell is defined as a shell constructed wholly from precast reinforced concrete sections, assembled one atop another, to form a freestanding, self-supporting cantilever. Vertical reinforcement and grout are placed in
15、cores as the precast sections are erected to provide structural continuity and stability. The use of precast panels as stay-in- place forms is considered cast-in-place construction. 1.2-Drawings Drawings of the chimney shall be prepared showing all features of the work, including the design strength
16、 of the concrete, the thickness of the concrete chimney shell, the size and position of reinforcing steel, details and dimen- sions of the chimney lining, and information on chimney accessories. 1.3-Regulations 1.3.1 The design and construction of the chimney shall meet the requirements of all ordin
17、ances and regulations of authorities having jurisdiction, except that where such requirements are less conservative than the comparable requirements of this standard, this standard shall govern. 1.3.2 Consideration shall be given to the recommendations of the Federal Aviation Administration with res
18、pect to chim- ney heights and aviation obstruction lighting and marking, and the standards of the Underwriters Laboratories regarding lightning protection and grounding. 1.4-Reference standards Standards of the American Concrete Institute, the Ameri- can Society of Civil Engineers, and the American
19、Society for ASTM A 706-96 ASTM C 33-93 ASTM C 150-95 ASTM C 309-95 ASTM C 595-95 Preparation of Notation for Concrete Building Code Requirements for Re- inforced Concrete Minimum Design Loads for Buildings and Other Structures Standard Specification for Deformed and Plain Billet Steel Bars for Concr
20、ete Reinforcement Standard Specification for Axle-Steel Deformed and Plain Bars for Concrete Reinforcement Standard Specification for Low-Alloy Steel Deformed Bars for Concrete Reinforcement Standard Specification for Concrete Aggregates Standard Specification for Portland Cement Standard Specificat
21、ion for Liquid Membrane-Forming Compounds for Curing Concrete Standard Specification for Blended Hydraulic Cement CHAPTER 2-MATERIALS 2.1 -General except as otherwise specified here. All materials and material tests shall conform to AC1 3 18, 2.2-Cement The same brand and type of cement shall be use
22、d through- out the construction of the chimney. The cement used shall conform to the requirements for Type I, Type II, Type III, or Type V of ASTM C 150, or Type IS or Type IP of ASTM C 595. 2.3-Aggregates 2.3.1 Concrete aggregates shall conform to ASTM C 33. 2.3.2 The maximum size of coarse aggrega
23、te shall be not larger than l/x of the narrowest dimension between forms nor larger than 1/2 the minimum clear distance between reinforcing bars. 2.4-Rei nfo rcemen t Reinforcement shall conform to ASTM A 615, A 617, or A 706. Deformed reinforcement with a specified yield stress fy exceeding 60,000
24、psi shall be permitted provided the ul- timate tensile strain shall equal or exceed 0.07. Copyright American Concrete Institute Provided by IHS under license with ACI Licensee=IHS Employees/1111111001, User=listmgr, listmgr Not for Resale, 03/05/2007 01:36:51 MSTNo reproduction or networking permitt
25、ed without license from IHS -,-,- REINFORCED CONCRETE CHIMNEYS 307-3 CHAPTER 3-CONSTRUCTION REQUIREMENTS 3.1 -General Concrete quality, methods of determining strength of con- crete, field tests, concrete proportions and consistency, mix- ing and placing, and formwork and details of reinforcement sh
26、all be in accordance with AC1 318, except as stated otherwise here. 3.2-Concrete quality less than 3000 psi at 28 days. The specified concrete compressive strength shall not be 3.3-Strength tests The 28-day compressive strength of the concrete shall be determined from a minimum of two sets of cylind
27、ers (consisting of three specimens each) per 8-hr shift (slipform) or per lift (jump form). For precast sections, a minimum of two sets shall be taken from each class of concrete cast each day and from each 100 yd3 of concrete placed each day. 3.4-Forms 3.4.1 Forms for the chimney shell shall be mad
28、e of metal, wood, or other suitable materials. If unlined wooden forms are used, they shall be of selected material with tongue-and- groove joints and shall be kept continuously wet to prevent shrinking and warping due to exposure to the elements. A nonstaining form oil shall be permitted to be used
29、. Form oil shall not be used unless it is a nonstaining type and it has been established that specified protective coatings or paint can be applied to concrete exposed to form oil. 3.4.2 Forms shall be sufficiently tight to prevent leakage of mortar. 3.4.3 No construction load shall be supported upo
30、n any part of the structure under construction until that portion of the structure has attained sufficient strength to safely support its weight and the loads placed thereon. 3.4.4 Forms shall be removed in such manner as to ensure the safety of the structure. Forms shall be permitted to be removed
31、after concrete has hardened to sufficient strength to maintain its shape without damage and to safely support all loads on it, including temporaiy construction loads. 3.4.5 Ties between inner and outer chimney shell forms shall not be permitted. 3.4.6 Construction joints shall be properly prepared t
32、o facilitate bonding. As a minimum, all laitance and loose material shall be removed. 3.5-Reinforcement placement 3.5.1 Circumferential reinforcement shall be placed around the exterior of, and secured to, the vertical bars. All reinforcing bars shall be tied at intervals of not more than 2 ft. Part
33、icular attention shall be paid to placing and securing the circumferential reinforcement so that it cannot bulge or be displaced during the placing and working of the concrete so as to result in less than the required concrete cover over this circumferential reinforcement. 3.5.2 Vertical reinforceme
34、nt projecting above the forms for the chimney shell or cores of precast sections shall be so supported as to prevent the breaking of the bond with the freshly placed concrete. 3.5.3 Not more than 50 percent of bars shall be spliced along any plane unless specifically permitted and approved by the re
35、sponsible engineer. 3.5.4 The concrete cover over the circumferential rein- forcement shall be a minimum of 2 in. for cast-in-place chimneys and 1- in. for precast units manufactured under plant control conditions. 3.6-Concrete placement No vertical construction joints shall be used for cast-in- pla
36、ce chimney shells. Horizontal construction joints for jump-form and precast construction shall be maintained at approximately uniform spacing throughout the height of the chimney. Concrete shall be deposited in approximately level layers no greater than 16-in. deep. Particular care shall be ex- erci
37、sed when casting concrete in thin wall sections and when casting cores of precast sections. Grout used to seat precast sections shall have a compressive strength at least equal to the design strength of the shell. 3.7-Concrete curing 3.7.1 Immediately after the forms have been removed all necessary
38、finishing of concrete shall be done. 3.7.2 As soon as fiiishing has been completed, both faces of concrete shall be cured by coating with a membrane cur- ing compound or other method approved by the engineer. The curing compound shall comply with ASTM C 309 and shall be applied in strict accordance
39、with the manufacturers recommendations. If coatings are to be applied to the con- crete, the curing compound shall be of a type compatible with these coatings. 3.8-Construction tolerances 3.8.1 The chimney shell shall be constructed within the tolerance limits set forth here. 3.8.1.1 Vertical alignm
40、ent o f centerpoint-The center- point of the shell shall not vary from its vertical axis by more than 0.001 times the height of the shell at the time of mea- surement, or l in., whichever is greater. Locally, the center- point of the shell shall not be changed by more than 1 in. per 10 ft. 3.8.1.2 D
41、iameter-The measured outside shell diameter at any section shall not vary from the specified diameter by more than 1 in. plus 0.01 times the specified or theoretical diame ter. 3.8.1.3 Wall thickness-The measured wall thickness shall not vary from the specified wall thickness by more than -/, in., +
42、/, in. for walls 10-in.-thick or less, or by more than-/, in., +1 in. for walls greater than 10-in.-thick. A single wall thickness measurement is defiied as the average of at least four measurements taken over a 60-deg arc. 3.8.2 Openings and embedments-Tolerances on the size and location of opening
43、s and embedments in the shell cannot Copyright American Concrete Institute Provided by IHS under license with ACI Licensee=IHS Employees/1111111001, User=listmgr, listmgr Not for Resale, 03/05/2007 01:36:51 MSTNo reproduction or networking permitted without license from IHS -,-,- 307-4 MANUAL OF CON
44、CRETE PRACTICE be uniformly established due to the varying degrees of accuracy required depending on the nature of their use. Appropriate tolerances for opening and embedment sizes and locations shall be established for each chimney. 3.9-Precast erection 3.9.1 The precast sections shall be erected i
45、n a manner and at a rate that ensures that sufficient strength has been attained in grout, core concrete, and all connecting components to safely support construction and applicable design loads. 3.9.2 Precast sections shall be keyed if necessary to transfer shear and grouted to level and seal joint
46、s. CHAPTER 4-SERVICE LOADS AND GENERAL DESIGN CRITERIA 4.1-General 4.1.1 The chimney shell shall be designed for the effects of gravity, temperature, wind, and earthquake in accordance with AC1 3 18, except as stated otherwise here. 4.1.2 The chimney shell shall be designed for load combi- 3 , natio
47、ns in accordance with the provisions of t. Design of chimney shell: Strength method. 4.1.3 4.1.3.1 The chimney shell shall not be less than 8-in. thick when cast in place, or less than 7-in. thick when com- posed of precast sections. 4.1.3.2 The chimney shell thickness, through openings, shall not b
48、e less than 1/24 the height of the opening. The thickened shell shall extend at least 1/2 the height of the opening above and below the opening. Properly designed buttresses or other means of lateral restraint may be used in place of this requirement; however, the buttresses shall be ignored when ca
49、lculating vertical strength. 4.1.3.3 When the internal diameter of the shell exceeds 28 ft, the minimum thickness shall be increased l/x in. for each 1-ft increase in internal diameter. 4.1.4 A chimney shell that supports lining loads shall com- ply with the requirements of this standard with the lining in place. The interaction of the liner with the shell shall be considered. 4.1.5 Consideration shall be given to loadings during the construction phase. 4.1.6 If required during construction, te
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