Guide to Nonlinear Modeling Parameters for Earthquake-Resistant Structures
Reported by ACl Committee 374
ACI 374.3R-16
Guide to NonlinearModelingParametersfor Earthquake-Resistant Structures
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GuidetoNonlinearModelingParametersfor Earthquake-ResistantStructures
Reportedby ACICommittee374
Jeffrey I. Dragovich Chair
Insung Kim* Secretary
Stavroula J. Pantazopoulou Chris P. PantelidesJeffrey Rautenberg Jose A. PincheiraMario E. Rodriguez Jose I. RestrepoMurat Satcioglu Felipe SavedaGuillermo Santana
Mark A. Aschheim John F. BonacciJoseph M. Bracci Sergio F BrenaNed M. Cleland Paul J. BrienenJuan Francisco Correal Daza Joe FerzliDavid C. Fiekds
Shamim A. Sheikh Mehrdad SasaniMyoungsu Shin Hitoshi ShioharaJohn H. Tessem Roberto StarkJohn W. Wallace Tom C. XiaFemando Yanez
Task group tht dvloped this gude Alar Celestin was als am mer f e tk group and pimary at.
Consulting Members
Andrew W. Tayfer
Special acknowledgements to Laura Basualdo Anna Birely Reza Dashtpeyma Wassim Ghannoum and Andrew Shuck for their contributions to this guide.
CONTENTS
This gaide provides information regarding nomlinear modeling ofresisting earthqagke lods. The reported modeling parameters ponents in special moment frame znd sructral wall systems(LDPs) performing nonlinear analyzis for performance-based provide a modeling option for licensed design professionalsseismic design of reinforced concrete building structures designedand derailed in accordance witt ACI 318.
CHAPTER1-INTRODUCTIONAND SCOPE p.21.1-Introduction p. 21.2-Scope p.2
CHAPTER2-NOTATIONAND DEFINITIONS p.3 2.1-Notation p. 32.2-Definitions p. 4
Keywords: backbone curve; beams; columns; coupling beams. earth- quake-resistant structures; flexure; joints; modeling parameters nonlinearanalyss; performance-based engineering; seismic design; shear special concrete moment frames; special concrete shear walls; special structuralwalls.
CHAPTER3-GENERAL p.43.1General p.4 3.2-Backbone curve selection procedure p. 5
CHAPTER4-NONLINEARMODELING PARAMETERSFORSPECIALCONCRETEMOMENT FRAMES p.5 4.1Modeling parameters for columns p. 54.2Modeling parameters for beams and beam-columnjoints (ASCE/SEI 41) p. 5
intended for guidance in planing designing xecting and ACI Committee Reports Guides and Commentaries areinspecting construtioThis doument is intended for the use of individuals who are petent to evaluate the significanceand limitations of its content and remendations and who will accept responsibility for the application of the material itcontains. The American Concrete Institute disclaims any and all reponsibility for the stated principles. The Institute shllnot 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 they shallerestatedinmandatory langugeforincoporation by the Architect/Engineer. @Seismicisolation
STRUCTURALWALLS AND COUPLING BEAMS p.7 CHAPTER5-NONLINEARMODELING PARAMETERSFORSPECIALCONCRETE
5.1Modeling parameters for special struetural walls andcoupling beams controlled by flexure p. 7
5.2-Modeling parameters for structuralcoupling beams controlled by shear p. 11
CHAPTER6-SUMMARYANDCONCLUSIONS p.12
CHAPTER7-REFERENCES p.12Authored documents p. 13
CHAPTER 1-INTRODUCTION AND SCOPE
1.1-Introduction
This guide provides nonlinear modeling parameters thatwill assist the licensed design professional (LDP) in the use of performance-based seismic design of new concretebuildings. Performance objectives are assigned for the given structure and pliance with the performanceobjectives are then evaluated based on the deformation ofstructural elements rather than evaluated based on strength under prescriptive requirements. Deformations in structuralponents allow the LDP to understand damage levels related to seismic hazards.
There are currently several documents that providegeneral analysis procedures for the design of new build- ings using performance-based engineering (ASCE/SEI 7:Structural Engineers Association of Northerm Califomia [SEAONC] 2008; Los Angeles Tall Buildings StructuralDesign Couneil [LATBSDC] 2014; Pacific EarthquakeAlthough these documents provide a means for seismic Engineering Research Center [PEER] [PEER/ATC 2010]).criteria that are similar to ASCE/SEI 41 they do not provide design indicative of earthquake hazards and acceptancethe required information for modeling nonlinear behavior ofa structural ponent based on detailing conditions such as the development of force-deformation backbone curvesthat can be used to generate the backbone curves of struc- shown in Fig. 1.1. This guide provides modeling parameterstural members of special moment frame and structural wallsystems detailed per Chapter 18 of ACI 318-14.
For example an engineer modeling the nonlinear defor-mation of a structural wall with specific reinforcement configurations for new design can select from the followingthree altematives: 1) develop modeling parameters fromtesting program; or 3) create force-deformation curves using existing experimental data; 2) develop and implement a new41) or guideline (ACI 369R) developed for seismic evalu- the information in the existing building standard (ASCE/SEIation and rehabilitation. The existing experimental data however are not always available and new testing programs may be limited by budget and project schedule. In addition the modeling parameters in the existing building standard do not always adequately represent the behavior of ponentsdesigned according to current codes.Furthemy @Seismicisolationnot be directly applied to new design due to f
Fig. 1.1Generalized force-deformation relations for struc-rural concrete ponents (ASCE/SEI 41). (Note: a b d e f and g are deformations as defined in the reportednonlinear modeling parameter tables.)
in parameter definition and requirements across documents.that can be used without performing one of the three alterna- This guide provides a set of nonlinear modeling parameterstives given.
1.2-Scope
This guide provides information about nonlinear modeling
(a) Special moment frames exracted from ASCE/SEI41 for which definitions and requirements are converted tothose of the codes for the design of new concrete buildings
average height of the beams framing into the joint hc in the direction of applied shear in. (mm)h= h = height of entire wall from base to top or clear effective shear span of wall in. (mm)height of wallsegment or wall pier in. (mm) moment of inertia of cracked section transformed= to concrete in.* (mma)1 = moment of inertia of gross concrete section about centroidal axis neglecting reinforcement in. (mm)L = length of member along which deformations are assumed to occur in. (mm)ts = development length in tension of deformed bar defoed wire orplain wire reinforcmen n (mm) assumed plastic hinge length minimum of thefor wall segments in. (mm) following: 0.5l the first-story height and 0.5h "y = length of entire wall or length of wall segment orwall pier considered in direction of shear force in. (mm)M = M = nominal flexural strength at section in.-Ib (N-mm) probable flexural strength of members with orwithout axial load determined using the propertiesof the member at the joint faces assuming a tensile stress in the longitudinal bars of at least 1.25f anda strength reduction factor Φ of 1.0 in.-Ib (N-mm) design axial force obtained from design loadp = binations that include overstrength factor or0 = determined from limit-state analysis Ib (N) generalized force demand in a ponent = yield strength of a ponent= ment in. (mm)= design shear force obtained from design load binations that include overstrength factor orV. design shear force for load binations including determined from limit-state analysis Ib (N)= earthquake effects Ib (N) (refer to ACI 318-14v. = nominal shear strength Ib (N) Sections 18.6.5.1 and 18.7.6.1.1)V. = shear strength of a column per ASCE/SEI 41 Eq. (10-3) Ib (N)V = shear demand on a column at flexural yielding ofplastic hinges per ASCE/SEI 41 Section 10.4.2.2.2 Ib (N)V = nominal shear strength provided by shearreinforce- ment Ib (N)= generalized deformation in. (mm) = = generalized yield deformation in (mm) yield strain of reinforcement in/in. (mm/mm)0 = generalized deformation radians generalized yield deformation radians0 中 = = strength reduction factorp = = yield curvature at section 1/in. (1/mm) ratio of nonprestressed tension reinforcementp′ = ratio of nonprestressed pression reinforcement ratio of A to bd producing balanced strain conditionP = ratio of A to b s
(b) Special structural walls and coupling beams extractedfrom ASCE/SEI 41 for which definitions and requirements are converted to those of the codes for the design of newconcrete buildings
from the latest experimental databases of structural po- (c) Special moment frames and structural walls developednents pliant with the requirements of Chapter 18 (ACI 318-14) for earthquake-resistant structures.
In regards to (c) the mean and mean minus one standarddeviation modeling parameter values are provided for these code-pliant specimen databases in an effort to demon-the LDP. The LDP can select modeling parameters based on strate a quantitative representation of data distribution forASCE/SEI 41 or the experimental database depending onproject constraints jurisdiction requirements or both.
The modeling parameters in this guide are meant to beused for the analytical modeling of structural ponents in earthquake-resistant systems as described. The guide however does not describe global behavior or provideinteraction between different systems in the buildings for example diaphragms and moment frames.
CHAPTER 2-NOTATION AND DEFINITIONS
2.1-Notation
A= grossarea of concrete setion bound by web thick-ness and length of section in the direction of shear force considered in.° (mm²)A gross area of concrete section in.² (mm²)A; effective cross-sectional area within a joint in a plane parallel to plane of beam reinforcementgenerating shear in the joint in.² (mm²) (ACI 318-14 Section 18.8.4.3)A = area of nonprestressed longitudinal tension rein-A= area of pression reinforcement in.² (mm²) forcement in.a (mm²)A = ‘ ueds m ua es jo ae (mm²)b = width of pression face of member in. (mm)b d = = web width or diameters of circular section in. (mm) distance from extreme pression fiber to centroidof longitudinal tension reinforcement in. (mm) effect ofhorizontal and vertical earthquake-inducedE = forcesE. E = modulus of elasticity of concrete psi (MPa) modulus of elasticity of reinforcement and struc-f tural steel psi (MPa) specified pressive strength of concrete psi= (MPa ' in MPa = 12f in psi)= specified yield strength of reinforcement psi (MPa) height of member along which deformations aresubgrade dimension from absolute base of wall to measured in. (mm)grade level in. (mn) @Seismicisolation
