Aci 318

ACI 318-08 - Seismic Requirements -- Luis E. Garcia

Seismic Design Requirements in ACI 318-08
By:

Chapter 1 General Requirements
Modifications in
Scope Terminology

Luis Enrique García
President American Concrete Institute – ACI – 2008-2009 Partner Proyectos y Diseños Ltda. Consulting Engineers Professor Universidad de los Andes Bogotá, Colombia

R1.1.9 – Provisions for earthquakeresistance
Commentary was expanded to:
Explain changes in terminology used Simplify adoption and interaction of ACI 318-08 with model codes and other documents

R1.1.9 – Provisions for earthquake resistance
In this version of ACI 318 (2008), for the first time, earthquake resistance requirements are defined in function of the Seismic Design Category — SDC required for the structure and notdirectly associated with the seismic risk zone. The minimum SDC to use is governed by the legally adopted general building code of which ACI 318 forms a part.
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ACI 318-08 - Seismic Requirements -- Luis E. Garcia

TABLE R1.1.9.1 — CORRELATION BETWEEN SEISMIC-RELATED TERMINOLOGY IN MODEL CODES
Code, standard, or resource document and edition ACI 318-08; IBC 2000, 2003; 2006; NFPA 5000,2003, 2006; ASCE 798, 7-02, 7-05; NEHRP 1997, 2000, 2003 BOCA National Building Code 1993, 1996, 1999; Standard Building Code 1994, 1997, 1999; ASCE 7-93, 7-95; NEHRP 1991, 7 93, 7 95; 1994 Uniform Building Code 1991, 1994, 1997
*SDC

Level of seismic risk or assigned seismic performance or design categories as defined in the Code

Chapter 2 Notation and Definitions
There were importantchanges in notation of the whole document and all individual Chapter notation was moved to Chapter 2. There are a few new definitions related to Chapter 21. All definitions, old and new, were moved to Chapter 2.

SCD* A, B

SCS C

SCD D, E, F

SPC† A, B

SPC C

SPC D; E

Seismic Zone 0, 1

Seismic Zone 2

Seismic Zone 3, 4

†SPC

= Seismic Design Category as defined in code,standard, or resource document. = Seismic Performance Category as defined in code, standard, or resource document

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Chapter 21 Earthquake-resistant structures
Chapter 21 was reorganized in function of Seismic Design Categories (SDC) A, B, C, and D, E, and F in incremental order from ordinary to special: A → B → C → D, E, F

Seismic Design Category and Energy Dissipation Capacity
SDC Seismic Di S i i Design Category Denomination (Energy di i ti (E dissipation capacity) Must comply with in ACI 318-08

A B C D, E, F

Chapters 1 to 19 and 22

Ordinary Intermediate Special

Chapters 1 to 19, 22, and 21.2 Chapters 1 to 19, 22, and 21.3 y 21.4 Chapters 1 to 19, 22, And 21.5 to 21.13

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ACI 318-08 - Seismic Requirements -- Luis E. Garcia

ACI 318-08 – Chapter 21Earthquake-resistant structures
Content 21.1 – General requirements 21.2 21 2 – Ordinary moment frames B 21.3 – Intermediate moment frames C 21.4 – Intermediate precast structural walls 21.5 – Flexural members of special moment frames 21.6 – Special moment frame members subjected to bending and axial load 21.7 – Joints of special moment frames D 21.8 – Special moment frames constructed using precast concrete21.9 – Special structural walls and coupling beams E 21.10 – Special structural walls constructed using precast concrete F 21.11 – Structural diaphragms and trusses 21.12 – Foundations 21.13 – Members not designated as part of the seismic-forceresisting system

21.1 – General requirements
Scope

Chapter 21 contains provisions considered to be the minimum requirements for a cast-in-place orprecast concrete structure capable of sustaining a series of oscillations into the inelastic range of response without critical deterioration in g strength. Therefore, the objective is to provide energy dissipation capacity in the nonlinear range of response.

TABLE R21.1.1 — SECTIONS OF CHAPTER 21 TO BE SATISFIED IN TYPICAL APPLICATIONS

Component resisting earthquake effect, unless otherwise...