ACI-350.3-2006.pdf
ACI 350.3-06 Seismic Design of Liquid-Containing Concrete Structures and Commentary (ACI 350.3-06) An ACI Standard Reported by ACI Committee 350 Seismic Design of Liquid-Containing Concrete Structures and Commentary ISBN 0-87031-222-7 Copyright by the American Concrete Institute, Farmington Hills, MI. All rights reserved. This material may not be reproduced or copied, in whole or part, in any printed, mechanical, electronic, film, or other distribution and storage media, without the written consent of ACI. The technical committees responsible for ACI committee reports and standards strive to avoid ambiguities, omissions, and errors in these documents. In spite of these efforts, the users of ACI documents occa- sionally find information or requirements that may be subject to more than one interpretation or may be incomplete or incorrect. Users who have suggestions for the improvement of ACI documents are requested to contact ACI. 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Sachdev Chair Jon B. Ardahl Vice Chair John W. Baker Secretary Walter N. BennettCarl A. Gentry*Dennis C. KohlJerry Parnes Lucian I. Bogdan Gautam Ghosh*Nicholas A. LegatosAndrew R. Philip Steven R. CloseCharles S. HanskatRamon E. Lucero*Narayan M. Prachand Patrick J. Creegan*Keith W. JacobsonAndrew R. Minogue Risto Protic* Ashok K. Dhingra*Dov KaminetzkyLawrence G. Mrazek*William C. Sherman* Robert E. DoyleM. Reza Kianoush*Javeed A. Munshi*Lawrence M. Tabat* Anthony L. FelderDavid G. Kittridge Subcommittee Members Iyad M. AlsamsamDaniel J. McCarthy Clifford T. Early, Jr.Carl H. Moon Paul HedliG. Scott Riggs Jerry A. HollandJohn F. Seidensticker Lawrence E. KaiserPaul J. St. John Salvatore MarquesPaul Zoltanetzky, Jr. Seismic Design of Liquid-Containing Concrete Structures and Commentary (ACI 350.3-06) AN ACI STANDARD REPORTED BY ACI COMMITTEE 350 Environmental Engineering Concrete Structures Consulting Members William Irwin Terry Patzias Lawrence Valentine *Members of Seismic Provisions Subcommittee. Seismic Provisions Subcommittee Chair. Seismic Provisions Subcommittee Secretary. SEISMIC DESIGN OF LIQUID-CONTAINING CONCRETE STRUCTURES350.3-1 Seismic Design of Liquid-Containing Concrete Structures and Commentary (ACI 350.3-06) REPORTED BY ACI COMMITTEE 350 This standard prescribes procedures for the seismic analysis and design of liquid-containing concrete structures. These procedures address the loading side of seismic design and are intended to complement ACI 350-06, Section 1.1.8 and Chapter 21. Keywords: circular tanks; concrete tanks; convective component; earth- quake resistance; environmental concrete structures; impulsive component; liquid-containing structures; rectangular tanks; seismic resistance; sloshing; storage tanks. INTRODUCTION The following paragraphs highlight the development of this standard and its evolution to the present format: From the time it embarked on the task of developing an ACI 318-dependent code, ACI Committee 350 decided to expand on and supplement Chapter 21, “Special Provisions for Seismic Design,” to provide a set of thorough and comprehensive procedures for the seismic analysis and design of all types of liquid-containing environmental concrete structures. The committees decision was influenced by the recognition that liquid-containing structures are unique structures whose seismic design is not adequately covered by the leading national codes and standards. A seismic design subcommittee was appointed with the charge to implement the committees decision. The seismic subcommittees work was guided by two main objectives: 1. To produce a self-contained set of procedures that would enable a practicing engineer to perform a full seismic analysis and design of a liquid-containing structure. This meant that these procedures should cover both aspects of seismic design: the “loading side” (namely the determination of the seismic loads based on the mapped maximum considered earthquake spectral response accelerations at short periods (Ss) and 1 second (S1) obtained from the Seismic Ground Motion maps Fig. 22-1 through 22-14 of ASCE 7-05, Chapter 22 and the geometry of the structure); and the “resistance side” (the detailed design of the structure in accordance with the provisions of ACI 350, so as to resist those loads safely); and 2. To establish the scope of the new procedures consistent with the overall scope of ACI 350. This required the inclusion of all types of tanksrectangular, as well as circular; and reinforced concrete, as well as prestressed. (Note: While there are currently at least two national standards that provide detailed procedures for the seismic analysis and design of liquid-containing structures (ANSI/AWWA 1995a,b), these are limited to circular, prestressed concrete tanks only). As the loading side of seismic design is outside the scope of ACI 318, Chapter 21, it was decided to maintain this practice in ACI 350 as well. Accordingly, the basic scope, format, and mandatory language of Chapter 21 of ACI 318 were retained with only enough revisions to adapt the chapter to environmental engineering structures. Provisions similar to Section 1.1.8 of ACI 318 are included in ACI 350. This approach offers at least two advantages: 1. It allows ACI 350 to maintain ACI 318s practice of limiting its seismic design provisions to the resistance side only; and 2. It makes it easier to update these seismic provisions so as to keep up with the frequent changes and improvements in the field of seismic hazard analysis and evaluation. ACI Committee Reports, Guides, Standards, and Commentaries are intended for guidance in planning, designing, executing, and inspecting construction. This Commentary is intended for the use of individuals who are competent to evaluate the significance and limitations of its content and recommendations and who will accept responsibility 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 therefrom. Reference to this commentary shall not be made in contract docu- ments. If items found in this Commentary are desired 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. ACI 350.3-06 supersedes 350.3-01 and became effective on July 3, 2006. Copyright © 2006, American Concrete Institute. All rights reserved including rights of reproduction and use in any form or by any means, including the making of copies by any photo process, or by any electronic or mechanical device, printed or written or oral, or recording for sound or visual reproduction or for use in any knowledge or retrieval system or device, unless permission in writing is obtained from the copyright proprietors. 350.3-2ACI STANDARD/COMMENTARY The seismic force levels and R-factors included in this standard provide results at strength levels, such as those included for seismic design in the 2003 International Building Code (IBC), particularly the applicable connection provisions of 2003 IBC, as referenced in ASCE 7-02. When comparing these provisions with other documents defining seismic forces at allowable stress levels (for example, the 1994 Uniform Building Code UBC or ACI 350.3-01), the seismic forces in this standard should be reduced by the applicable factors to derive comparable forces at allowable stress levels. The user should note the following general design methods used in this standard, which represent some of the key differences relative to traditional methodologies, such as those described in ASCE (1984): 1. Instead of assuming a rigid tank for which the acceleration is equal to the ground acceleration at all locations, this standard assumes amplification of response due to natural frequency of the tank; 2. This standard includes the response modification factor; 3. Rather than combining impulsive and convective modes by algebraic sum, this standard combines these modes by square-root-sum-of-the-squares; 4. This standard includes the effects of vertical acceleration; and 5. This standard includes an effective mass coefficient, applicable to the mass of the walls. SEISMIC DESIGN OF LIQUID-CONTAINING CONCRETE STRUCTURES350.3-3 CONTENTS CHAPTER 1GENERAL REQUIREMENTS 5 1.1Scope 1.2Notation CHAPTER 2TYPES OF LIQUID-CONTAINING STRUCTURES . 11 2.1Ground-supported structures 2.2Pedestal-mounted structures CHAPTER 3GENERAL CRITERIA FOR ANALYSIS AND DESIGN. 13 3.1Dynamic characteristics 3.2Design loads 3.3Design requirements CHAPTER 4EARTHQUAKE DESIGN LOADS 15 4.1Earthquake pressures above base 4.2Application of site-specific response spectra CHAPTER 5EARTHQUAKE LOAD DISTRIBUTION. 21 5.1General 5.2Shear transfer 5.3Dynamic force distribution above base CHAPTER 6STRESSES. 27 6.1Rectangular tanks 6.2Circular tanks CHAPTER 7FREEBOARD. 29 7.1Wave oscillation CHAPTER 8EARTHQUAKE-INDUCED EARTH PRESSURES 31 8.1General 8.2Limitations 8.3Alternative methods CHAPTER 9DYNAMIC MODEL. 33 9.1General 9.2Rectangular tanks (Type 1) 9.3Circular tanks (Type 2) 9.4Seismic response coefficients Ci, Cc, and Ct 9.5Site-specific seismic response coefficients Ci, Cc, and Ct 9.6Effective mass coefficient 9.7Pedestal-mounted tanks CHAPTER 10COMMENTARY REFERENCES 53 350.3-4ACI STANDARD/COMMENTARY APPENDIX ADESIGN METHOD.55 A.1General outline of design method APPENDIX BALTERNATIVE METHOD OF ANALYSIS BASED ON 1997 Uniform Building Code.57 B.1Introduction B.2Notation (not included in Section 1.2 of this standard) B.3Loading side, general methodology B.4Site-specific spectra (Section 1631.2(2) B.5Resistance side B.6Freeboard SEISMIC DESIGN OF LIQUID-CONTAINING CONCRETE STRUCTURES350.3-5 STANDARDCOMMENTARY 1.1Scope This standard describes procedures for the design of liquid-containing concrete structures subjected to seismic loads. These procedures shall be used in accordance with Chapter 21 of ACI 350-06. R1.1Scope This standard is a companion standard to Chapter 21 of the American Concrete Institute, “Code Requirements for Environ- mental Engineering Concrete Structures and Commentary (ACI 350-06)” (ACI Committee 350 2006). This standard provides directions to the designer of liquid- containing concrete structures for computing seismic forces that are to be applied to the particular structure. The designer should also consider the effects of seismic forces on components outside the scope of this standard, such as piping, equipment (for example, clarifier mechanisms), and connecting walkways where vertical or horizontal movements between adjoining structures or surrounding backfill could adversely influence the ability of the structure to function properly (National Science Foundation 1981). Moreover, seismic forces applied at the interface of piping or walkways with the structure may also introduce appreciable flexural or shear stresses at these connections. R1.2Notation CHAPTER 1GENERAL REQUIREMENTS 1.2Notation As=cross-sectional area of base cable, strand, or conventional reinforcement, in.2 (mm2) b=ratio of vertical to horizontal design accel- eration B=inside dimension (length or width) of a rectan- gular tank, perpendicular to the direction of the ground motion being investigated, ft (m) Cc, Ci, and Ct=period-dependent seismic response coeffi- cients defined in 9.4 and 9.5. Cl, Cw=coefficients for determining the fundamental frequency of the tank-liquid system (refer to Eq. (9-24) and Fig. 9.3.4(b) Cs=period-dependent seismic coefficient d,dmax=freeboard (sloshing height) measured from the liquid surface at rest, ft (m) D=inside diameter of circular tank, ft (m) EBP=excluding base pressure (datum line just above the base of the tank wall) Ec=modulus of elasticity of concrete, lb/in.2 (MPa) Es=modulus of elasticity of cable, wire, strand, or conventional reinforcement, lb/in.2 (MPa) Fa=short-period site coefficient (at 0.2 second period) from ASCE 7-05, Table 11.4-1 Fv=long-period site coefficient (at 1.0 second period) from ASCE 7-05, Table 11.4-2 Gp=shear modulus of elastomeric bearing pad, lb/in.2 (MPa) g=acceleration due to gravity 32.17 ft/s2 (9.807 m/s2) EBP refers to the hydrodynamic design in which it is necessary to compute the overturning of the wall with respect to the tank floor, excluding base pressure (that is, excluding the pressure on the floor itself). EBP hydrodynamic design is used to determine the need for hold-downs in nonfixed base tanks. EBP is also used in determining the design pressure acting on walls. (For explanation, refer to Housner 1963.) For Cs, refer to “International Building Code (IBC)” (International Code Council 2003), Section 1617.4. 350.3-6ACI STANDARD/COMMENTARY STANDARDCOMMENTARY hc = height above the base of the wall to the center of gravity of the convective lateral force for the case excluding base pressure (EBP), ft (m) hc= height above the base of the wall to the center of gravity of the convective lateral force for the case including base pressure (IBP), ft (m) hi =height above the base of
