An ACl Standard
Code Requirements for SeismicAnalysisand Design of Liquid-Containing ConcreteStructures (ACI 350.3-20) and Commentary
ReportedbyAClCommittee350
CodeRequirementsforSeismicAnalysis andDesign ofLiquid-ContainingConcrete Structures (ACI350.3-20) and Commentary
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CodeRequirementsforSeismicAnalysisand DesignofLiquid-ContainingConcreteStructures (ACI350.3-20)andCommentary
AnACI Standard
ReportedbyJointACICommittee350
Memibers of Seismic Prowvisions Subcon ittee.
Seismic Proni ne Chait.
desin of liquid-containing concrete stctres. These procedures This Code prescribes procedures for the seismic analysis andplememr Sectiom 1. 1.9 and Chapter 13 of ACI 350-20. adress the loading side of seismic design and are intended t0
inendedfor guidancen plaing desining xetn an ACI Commitee Repors Guides and Commentaries areinsetingontonhisdoutsenddfthu of individuals who are petent to evaluate the significanceand limitations of its content and remendations and who odedscontains. The American Concrete Institute disclaims any and allresponsibility for the stated principles.The Institute shallnot be 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 the Architect/Engineer to be a part of the contract documents by the Architect/Engineer. they shall be restated inmandatory language for incorporation
Andrew R. Minogue Secretary
Shashiprakash G. SuraliLawrence M. Tabet* John M. TehaneyWiiam A. Wallace Miroslav VejvodaJeffrey S. Ward
Keywerds: circular tanks; concrete tanks; convective ponent; earth- qakeresistance; environmenal concrete stuctures: mpuliveonent;lquid-tinng st tanltak sismresta slhn: storage tanks.
PREFACE
From the time it embarked on the task of developing an ACI 318-dependent code ACI Commitee 350 decided to expand onosdssdds hensive procedures for the seismic analysis and design of monly used types ofliquidcontaining structures of crcular andunique structures whose seismic design is not adequatly covered by the leading national codes and standards A scismic design rectangular configurations.The mittes decision was infuenced by therecognition that liquid-containing structures aresubmitte was appointed with the charge to implement the mittce’s decision.
The seismic submittce's work was guided by two main objectives:
(1) Produce a self-contained set of procedures that would enable a practicing engineer to perform a full seismic analysis anddesign of a liquid-containing structure. These procedures should cover both aspects of seismic design: the “loading side which is the determination of the seismic loads based on the mapped risk-adjusted maximum considered earthquake spec-tral response accelerations at short periods (S ) and 1 second (S ) obtained from the Seismic Ground Motion maps (ASCE/SEI 7-16Chapte22)and th gemetry ofthestructure; and the“resistance side which is thedetaild desig ofthe structure in accordance with the provisions of ACI 350-20 to resist those loads safely.
all types of tanksretangular as wellas crcular; and renforced conerete as well as prestressd. (2) Establish the scope of the new procedures consistent with the overall scope of ACI 350-20. This required the inclusion of
There are currently at lcast two national standards that provide detailed procedures for the seismic analysis and design ofliquid-containing structures: ANSI/AWWA D110-13 (R18) which is limited to circular prestressed concrete tanks; and ANS1/
as well.Accordingly the basic scope fomat and mandatory language of Chapter 21 of AC1 31811 were retained with only As the loading side of seismic design is outside the scope of ACI 318 it was decided to maintain this practice in ACI350enough revisions to adapt the seismic provisions to cnvironmental engincering structures. Provisions similar to Section 1.1.9 ofACI 318-11 are included in AC1 350. This approach offers at least two advantages:
(1) Allows ACI 350 to maintain the ACI 318 practice of limiting its seismic design provisions to the resistance side only.opds
seismic hazard analysis and evaluation.
The forces due to carthquake determined in accordance with this Code are intended to be used in the determination of loadthis Code provide results at strength levels such as those included for seismic design in the International Code Council (ICC) effects due to earthquake E in accordance with Chapter 9 of ACI 350-20. The seismic force levels and R-factors included inASCE/SEI7-16.When paring these provisions with other documents defining seismic forces at allowable stress levels forexample the 1997 Uniform Building Code [UBC-1997]) the seismic forces in this Code should be reduced by the applicablefactors to derive parable forces at allowable stress levels.
Users should note the following general design methods used in this Code which represent the evolution of seismic designof liquid-containing structures over a number of years since ASCE (1984) as follows:
assumes amplification of response due to natural frequcney of the tank.(b) The response modification factor is included. (c) Rather than bining impulsive and convective modes by algebraic sum this Code bines these modes by(d) The effects of vertical acceleration are included. square-root-sum-of-the-squares.(e) An effective mass coeficient applicable to the mass of the walls is included.than water refer to Veletsos and Shivakumar (1997). For further information on seismic behavior of liquid-containing structures refer to Housner (1957 1963b). For fluids other
CONTENTS
CHAPTER6-STRESSES p.266.1--Rectangular tanks p. 266.2-Cireular tanks p 26
PREFACE p.2
CHAPTER1-GENERALREQUIREMENTS p.4 1.1-Scope.p.41.2-Notation p.41.3Definitions p. 10
CHAPTER7-FREEBOARD p.27 7.1-Wave oscillation. p.27
CHAPTER8-EARTHQUAKE-INDUCEDEARTH PRESSURES p.328.1-General p.32 8.2-Limitations p.338.3-Altemative methods.p.33
STRUCTURES p.11 CHAPTER2-TYPESOFLIQUID-CONTAINING2.1Ground-supported structures p.112.2-Pedestal-mounted struetures p. 12
CHAPTER9-DYNAMICMODEL p.349.2--Rectangular tanks (Type 1).p.36 9.1General p.349.4-Seismic response coefficients C C and C p.44 9.5Site-speifie scismie response coeficients C Cand Cp.45 9.6--Effective mass coefficient E p. 469.7Pedestal-mounted tanks p. 46
AND DESIGN p.13 CHAPTER3-GENERALCRITERIAFORANALYSIS3.1-Dynamic characteristies p. 133.2-Design loads p. 13 3.3Design requirements p. 13
CHAPTER4-EARTHQUAKEDESIGNLOADS p.144.1--Earthquake pressures above base of tank wall. p. 144.2--Application of site-specific response spectra p. 17
CHAPTER10-COMMENTARYREFERENCES p.47
CHAPTER5-EARTHQUAKELOAD DISTRIBUTION p.195.1General p. 195.2-Shear transfer.p. 19 5.3Dynamic force distribution above base of tank wall p.21
APPENDIXA-DESIGN METHOD p.49A.1General outline of design method p. 49
