Regulations for Seismic Design - World List 2024

	United States [ Back to Country Index ]
REGULATION
Name		The International Building Code
Year		2018
Issued by		Regulatory agencies at the Federal, State and Local levels of government typically adopt by reference the International Building Code, 2018 Edition, published by the International Code Council, 2018. https://www.iccsafe.org/products-and-services/i-codes/2018-i-codes/ibc/
PDF file*
		*already offered for previous List or newly provided for current List
INQUIRY SHEET
About the edition		The International Building Code specifies most structural design criteria through reference to a series of national consensus standards developed by professional and industry associations. General requirements, loading and system selection criteria are adopted by reference to the ASCE 7-16 standard “Minimum Design Loads and Associated Criteria for Buildings and Other Structures,” published by the American Society of Civil Engineers, 2016 (https://www.asce.org/asce-7/).  Material-specific design criteria including capacity determination and detailing criteria are contained in standards published by the American Institute of Steel Construction (AISC-360-16, 341-16, 358-16); the American Concrete Institute (ACI 318-14); the Masonry Society (TMS 402/602-16); and the American Wood Council (NDS-2018). Under ASCE 7-16, buildings are classified into one of four Risk Categories associated with the structure’s intended use or occupancy. Design criteria tied to each Risk Category are intended to meet acceptable target reliabilities, taken as not greater than a 10% risk of collapse for ordinary occupancy (Risk Category I & II) buildings; 5% for high occupancy buildings and buildings with substantive quantities of hazardous materials (Risk Category III) and 2.5% for buildings critical to emergency response and recover including hospitals, fire stations, and emergency communications centers (Risk Category IV), all conditioned on the occurrence of a reference Risk-Targeted Maximum Considered Earthquake (MCER) shaking intensity. Throughout most of the U.S. the MCER is defined as occurring at that hazard level that produces a 1% probability of collapse in 50 years, considering a standard fragility and the site-specific seismic hazard. Individual return periods generally vary from 1,500 to 3,000 years. At sites within a few kilometers of major active faults, the MCER is defined as the 84th percentile shaking intensity associated with a characteristic (practical maximum) earthquake magnitude on the proximate fault. In addition to these collapse safety goals, criteria also seek to secure nonstructural components in events having 2/3 the MCER shaking intensity and to provide increased probability of post-earthquake functionality for Risk Category IV structures. The standard specifies minimum required lateral strength reduced from theoretical elastic spectral response for the MCER factored by 2/3R, where R is a structural system-specific response modification factor intended to account for inherent inelastic response capability. Distribution of forces throughout the structure may be determined by a simplified equivalent lateral force analysis, modal response spectrum analysis or linear response history analysis. Drifts under the specified seismic forces is limited based on Risk Category, building height, and structural system. Nonlinear response history analysis may also be used to determine required design forces and drift compliance. The standard also specifies required strength for anchorage of nonstructural components and functionality criteria for certain designated seismic systems. For the seismic retrofit of existing buildings, the International Existing Building Code is used (https://codes.iccsafe.org/content/IEBC2018P3). The latest version was produced in 2018. The IEBC adopts another standard ASCE/SEI 41-17, “Seismic Evaluation and Retrofit of Existing Buildings,” that enables evaluation of a structure’s ability to meet one of several performance levels (Immediate Occupancy, Life Safety, Collapse Prevention) for a given intensity of shaking. The standard presents a three-tiered process for seismic evaluation according to a range of building performance including: a deficiency-based procedure tied to specific model building types and analytical procedures of varying complexity. The IEBC specifies the required performance for buildings conforming to different Risk Categories, as defined in the IBC. The IEBC requires upgrade of structures only upon the occurrence of certain triggering events including occupancy change, substantive alteration or repair. The International Residential Code (IRC) is also frequently adopted and contains many prescriptive seismic requirements for residential construction (https://codes.iccsafe.org/content/IRC2018P3).
		The development of the next series of standards is currently underway.  The next version of the ASCE 7 standard is ASCE 7-22 and is targeted for adoption in the 2024 International Building Code.
Language		English
Distributed media		See links above in the “About the edition” section. A free version of the Earthquake Loads Section of the 2018 IBC is at: https://codes.iccsafe.org/content/IBC2018P3/chapter-16-structural-design#IBC2018P3_Ch16_Sec1613
Free or charged		Documents published by the International Code Council and the Building Seismic Safety Council are free. Documents published by the American Society of Civil Engineers are copyrighted and must be purchased.
Editorial Note