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1、 *Members of ACI 350 Seismic Design Subcommittee who prepared this report. Charles S. Hanskat Chairman Lawrence M. Tabat* Secretary Nicholas A. Legatos* Subcommittee Chairman Andrew R. Philip* Subcommittee Secretary James P. ArchibaldA. Ray FranksonDov KaminetzkyDavid M. Rogowsky Jon B. Ardahl*Anand
2、 B. Gogate*M. Reza Kianoush*Satish K. Sachdev Walter N. BennettWilliam J. Hendrickson*David G. KittridgeWilliam C. Schnobrich* Steven R. CloseJerry A. HollandLarry G. Mrazek*Sudhaker P. Verma Ashok K. Dhingra*William J. IrwinJerry ParnesRoger H. Wood Anthony L. Felder Voting Subcommittee Members Osa
3、ma Abdel-Aai*Clifford T. EarlyJack MollWilliam C. Sherman* John BakerClifford GordonCarl H. MoonLauren A. Sustic Patrick J. Creegan*Paul HedliJaveed A. Munshi*Lawrence J. Valentine David A. CrockerKeith W. JacobsonTerry PatziasMiroslav Vejvoda Ernst T. CviklDennis C. KohlNarayan M. PrachandPaul Zolt
4、anetzky Robert E. DoyleBryant MatherJohn F. Seidensticker Seismic Design of Liquid-Containing Concrete Structures (ACI 350.3-01) and Commentary (350.3R-01) REPORTED BY ACI COMMITTEE 350 ACI Committee 350 Environmental Engineering Concrete Structures SEISMIC DESIGN OF LIQUID-CONTAINING CONCRETE STRUC
5、TURES350.3/350.3R-1 Seismic Design of Liquid-Containing Concrete Structures (ACI 350.3-01) and Commentary (ACI 350.3R-01) REPORTED BY ACI COMMITTEE 350 This standard prescribes procedures for the seismic analysis and design of liquid-containing concrete struc- tures. These procedures address the “lo
6、ading side” of seismic design and shall be used in accordance with ACI 350-01/ACI 350R-01, Chapter 21. Keywords: circular tanks; concrete tanks; convective component; earth- quake resistance; environmental concrete structures; impulsive component; liquid-containing structures; rectangular tanks; sei
7、smic resistance; slosh- ing; storage tanks. INTRODUCTION The following outline highlights the development of this document and its evolution to the present format: From the time it embarked on the task of developing an “ACI 318-dependent” code, Committee 350 decided to expand on and supplement Chapt
8、er 21, “Special Provi- sions for Seismic Design,” in order 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- contain
9、ing structures are unique structures whose seis- mic design is not adequately covered by the leading national codes and standards. A seismic design sub- committee was appointed with the charge to implement the committees decision. The seismic subcommittees work was guided by two main objectives: (a)
10、 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 “load- ing side” (namely the determination of the
11、seismic loads based on the seismic zone of the site, the speci- fied effective ground acceleration, and the geometry of the structure), and the “resistance side” (the detailed design of the structure in accordance with the provi- sions of the code, so as to safely resist those loads). (b) To establi
12、sh 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. While there are currently at least two national stan- dards that provide detailed proce
13、dures for the seismic analysis and design of liquid-containing structures (References 17 and 18), these are limited to circular, prestressed concrete tanks only. As the “loading side” of seismic design is outside the scope of Chapter 21, ACI 318, it was decided to maintain this practice in ACI 350 a
14、s 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 environmen- tal engineering structures. This approach offers at least two ad- vantages: (a) It allows ACI 350 to maintain ACI 318s practice o
15、f limiting its seismic design provisions to the “resistance side” only; and (b) it makes it easier to update these seismic provi- sions so as to keep up with the frequent changes and improve- ments in the field of seismic hazard analysis and evaluation. The seismic force levels and Rw-factors includ
16、ed herein pro- vide results at allowable stress levels, such as are included for seismic design in the 1994 Uniform Building Code. When comparing these provisions with other documents defining ACI Committee Reports, Guides, Standards, and Commentaries are in- tended for guidance in planning, designi
17、ng, executing, and inspecting con- struction. 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 Conc
18、rete Institute disclaims any and all responsibility for the stated principles. The Institute shall not be li- able for any loss or damage arising therefrom. Reference to this commen- tary shall not be made in contract documents. If items found in this Commentary are desired by the Architect/Engineer
19、 to be a part of the con- tract documents, they shall be restated in mandatory language for incorpora- tion by the Architect/Engineer. ACI 350.3-01/350.3R-01 became effective on December 11, 2001. Copyright 2001, American Concrete Institute. All rights reserved including rights of reproduction and u
20、se 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 record- ing for sound or visual reproduction or for use in any knowledge or retrieval system or device, unless permission in writing is obtai
21、ned from the copy- right proprietors. 350.3/350.3R-2ACI STANDARD/COMMENTARY seismic forces at strength levels (for example, the 1997 Uni- form Building Code or the 2000 International Building Code), the seismic forces herein should be increased by the applicable factors to derive comparable forces a
22、t strength levels. The user should note the following general design methods used herein, which represent some of the key differences in methods relative to traditional methodologies used, such as in Reference 3: (1) Instead of assuming a rigid tank directly accel- erated by ground acceleration, thi
23、s documents assumes ampli- fication of response due to natural frequency of the tank; (2) this document includes the response modification factor; (3) rather than combining impulsive and convective modes by al- gebraic sum, this document combines these nodes by square- root-sum-of-the-squares; (4) t
24、his document includes the effects of vertical acceleration; and (5) this document includes an ef- fective mass coefficient, applicable to the mass of the walls. -,-,- SEISMIC DESIGN OF LIQUID-CONTAINING CONCRETE STRUCTURES350.3/350.3R-3 CONTENTS CHAPTER 1GENERAL REQUIREMENTS 350.3/350.3R-5 1.1Scope
25、1.2Notation CHAPTER 2TYPES OF LIQUID-CONTAINING STRUCTURES .350.3/350.3R-11 2.1Ground-supported structures 2.2Pedestal-mounted structures CHAPTER 3GENERAL CRITERIA FOR ANALYSIS AND DESIGN350.3/350.3R-13 3.1Dynamic characteristics 3.2Design loads 3.3Design requirements CHAPTER 4EARTHQUAKE DESIGN LOAD
26、S .350.3/350.3R-15 4.1Earthquake pressures above base 4.2Application of site-specific response spectra CHAPTER 5EARTHQUAKE LOAD DISTRIBUTION350.3/350.3R-21 5.1General 5.2Shear transfer 5.3Dynamic force distribution above base CHAPTER 6STRESSES350.3/350.3R-27 6.1Rectangular tanks 6.2Circular tanks CH
27、APTER 7FREEBOARD 350.3/350.3R-29 7.1Wave oscillation CHAPTER 8EARTHQUAKE-INDUCED EARTH PRESSURES 350.3/350.3R-31 8.1General 8.2Limitations 8.3Alternative methods -,-,- 350.3/350.3R-4ACI STANDARD/COMMENTARY CHAPTER 9DYNAMIC MODEL.350.3/350.3R-33 9.1General 9.2Rectangular tanks (Type 1) 9.3Circular ta
28、nks (Type 2) 9.4Spectral amplification factors Ci and Cc 9.5Effective mass coefficient 9.6Pedestal-mounted tanks CHAPTER 10COMMENTARY REFERENCES350.3/350.3R-49 APPENDIX ADESIGN METHOD350.3/350.3R-51 RA.1General outline of design method -,-,- SEISMIC DESIGN OF LIQUID-CONTAINING CONCRETE STRUCTURES350
29、.3/350.3R-5 STANDARDCOMMENTARY 1.1Scope This document describes procedures for the design of liquid-containing concrete structures subjected to seis- mic loads. These procedures shall be used in accor- dance with Chapter 21 of ACI 350-01. R1.1Scope This document is a companion document to Chapter 21
30、 of the American Concrete Institute Committee code 350, “Code Requirements for Environmental Engineering Concrete Structures (ACI 350-01) and Commentary (350R-01).”(1) This document provides directions to the designer of liquid- containing concrete structures for computing seismic forces that are to
31、 be applied to the particular structure. The designer should also consider the effects of seismic forces on compo- nents outside the scope of this document, such as piping, equipment (for example, clarifier mechanisms), and connect- ing walkways, where vertical or horizontal movements between adjoin
32、ing structures or surrounding backfill could adversely influence the ability of the structure to function properly.(2) 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. R1.2Notati
33、on CHAPTER 1GENERAL REQUIREMENTS 1.2Notation Ac=spectral acceleration, expressed as a frac- tion of the acceleration due to gravity, g, from a site-specific response spectrum, corresponding to the natural period of the first (convective) mode of sloshing, Tc, at 0.5% of critical damping Ai=spectral
34、acceleration, expressed as a frac- tion of the acceleration due to gravity, g, from a site-specific response spectrum, corresponding to the natural period of the tank and the impulsive component of the stored liquid, Ti, at 5% of critical damping As=cross-sectional area of base cable, strand, or con
35、ventional reinforcement, in.2 (mm2) Av=spectral acceleration, expressed as a frac- tion of the acceleration due to gravity, g, from a site-specific response spectrum, corresponding to the natural period of vibra- tion of vertical motion, Tv, of the tank and the stored liquid, at 5% of critical dampi
36、ng b=ratio of vertical to horizontal design accel- eration B=inside length of a rectangular tank, perpen- dicular to the direction of the earthquake force, ft (m) C=period-dependent spectral amplification factor (Cc, Ci, or Cv as defined below) Cc=period-dependent spectral amplification factor for t
37、he horizontal motion of the con- vective component (for 0.5% of critical damping) (Eq. (9-33) -,-,- 350.3/350.3R-6ACI STANDARD/COMMENTARY STANDARDCOMMENTARY Ci=period-dependent spectral amplification factor for the horizontal motion of the impul- sive component (for 5% of critical damping) (Eq. (9-3
38、1) and (9-32) Cl, Cw=coefficients for determining the fundamental frequency of the tank-liquid system (see Eq. (9-24) and Fig. 9.10) Cv=period-dependent spectral amplification factor for vertical motion of the contained liquid (Eq. (4-16) d,dmax=freeboard (sloshing height) measured from the liquid s
39、urface 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) Gp=shear m
40、odulus 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 neces- sary to compute the overturning of the wall with respect to the tank floor, excluding base pressure (that is, excluding the pressure on
41、the floor itself). EBP hydrodynamic design is used to determine the need for hold-downs in non-fixed base tanks. EBP is also used in determining the design pressure acting on walls. (For explanation, see Reference 3) h = as defined in R9.2.4, ft (m) IBP refers to the hydrodynamic design in which it
42、is neces- sary to investigate the overturning of the entire structure with respect to the foundation. IBP hydrodynamic design is used to determine the design pressure acting on the tank floor and the underlying foundation. This pressure is trans- ferred directly either to the subgrade or to other su
43、pporting structural elements. IBP accounts for moment effects due to dynamic fluid pressures on the bottom of the tank by increasing the effective vertical moment arm to the applied forces. (For explanation, see Reference 3) hc (EBP), hc (IBP)= height above the base of the wall to the center of grav
44、ity of the convective lateral force, ft (m) hi(EBP), hi (IBP)= height above the base of the wall to the center of gravity of the impulsive lateral force, ft (m) hr=height from the base of the wall to the cen- ter of gravity of the tank roof, ft (m) hw=height from the base of the wall to the cen- ter
45、 of gravity of the tank shell, ft (m) HL=design depth of stored liquid, ft (m) Hw=wall height (inside dimension), ft (m) I=importance factor, from Table 4(c) IBP=Including Base Pressure (datum line at the base of the tank including the effects of the tank bottom and supporting structure) k=flexural
46、stiffness of a unit width of a rectilin- ear tank wall, lb/ft2 (kPa) ka=spring constant of the tank wall support system, lb/ft2 (kPa) Ka=active coefficient of lateral earth pressure Ko=coefficient of lateral earth pressure at rest L=inside length of a rectangular tank, parallel to the direction of t
47、he earthquake force, ft (m) Lp=length of individual elastomeric bearing pads, in. (mm) Ls=effective length of base cable or strand taken as the sleeve length plus 35 times the strand diameter, in. (mm) m=mass = mi + mw, lb-s2/ ft4 (kN.s2/m4) -,-,- SEISMIC DESIGN OF LIQUID-CONTAINING CONCRETE STRUCTU
48、RES350.3/350.3R-7 STANDARDCOMMENTARY mi=impulsive mass of contained liquid per unit width of a rectangular tank wall, lb-s2/ ft4 (kN.s2/m4) mw=mass per unit width of a rectangular tank wall, lb-s2/ ft4 (kN.s2/m4) Mb=bending moment on the entire tank cross section just above the base of the tank wall
49、, ft-lb (N.m) Mo=overturning moment at the base of the tank including the tank bottom and supporting structure, ft-lb (kN.m) Ncy=in circular tanks, hoop force at liquid level y, due to the convective component of the accelerating liquid, pounds per foot of wall height (kN/m) Nhy=in circular tanks, hydrodynamic hoop force a