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NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards' was established by an act of Congress on March 3, 1901. The Bureau's overall goal is to strengthen and advance the Nation's science and technology and facilitate their effective application for public benefit. To this end, the Bureau conducts research and provides: (1) a basis for the Nation's physical measurement system, (2) scientific and technological services for industry and government, (3) a technical basis for equity in trade, and (4) technical services to promote public safety. The Bureau's technical work is performed by the National Measurement Laboratory, the National Engineering Laboratory, and the Institute for Computer Sciences and Technology,

THE NATIONAL MEASUREMENT LABORATORY provides the national system of physical and chemical and materials measurement; coordinates the system with measurement systems of other nations and furnishes essential services leading to accurate and unitorm physical and chemical measurement throughout the Nation's scientific community, industry, and commerce; conducts materials research leading to improved methods of measurement, standards, and data on the properties of materials needed by industry, commerce, educational institutions, and Government; provides advisory and research services to other Government agencies; develops, produces, and distributes Standard Reference Materials; and provides calibration services. The Laboratory consists of the following centers:

Absolute Physical Quantities: – Radiation Research – Thermodynamics and
Molecular Science — Analytical Chemistry Materials Science.

THE NATIONAL ENGINEERING LABORATORY provides technology and technical services to the public and private sectors to address national needs and to solve national problems; conducts research in engineering and applied science in support of these efforts; builds and maintains competence in the necessary disciplines required to carry out this research and technical service; develops engineering data and measurement capabilities; provides engineering measurement traceability services; develops test methods and proposes engineering standards and code changes; devy "ps and proposes new engineering practices; and develops and improves mechanisms to tra er results of its research to the ultimate user. The Laboratory consists of the following centers:

Applied Mathematics – Electronics and Electrical Engineering? – Mechanical
Engineering and Process Technology – Building Technology – Fire Research
Consumer Product Technology – Field Methods.

THE INSTITUTE FOR COMPUTER SCIENCES AND TECHNOLOGY conducts research and provides scientific and technical services to aid Federal agencies in the selection, acquisition, application, and use of computer technology to improve effectiveness and economy in Government operations in accordance with Public Law 89-306 (40 U.S.C. 759), relevant Executive Orders, and other directives; carries out this mission by managing the Federal Information Processing Standards Program, developing Federal ADP standards guidelines, and managing Federal participation in ADP voluntary standardization activities; provides scientific and technological advisory services and assistance to Federal agencies; and provides the technical foundation for computer-related policies of the Federal Government. The Institute consists of the following centers:

Programming Science and Technology – Computer Systems Engineering.

"Headquarters and Laboratories at Gaithersburg, MD, unless otherwise noted;
mailing address Washington, DC 20234.
Some divisions within the center are located at Boulder, CO 80303.

Development of a Probability Based Load Criterion
for American National Standard A58

Building Code Requirements for Minimum Design Loads
in Buildings and Other Structures

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U.S. DEPARTMENT OF COMMERCE, Philip M. Klutznick, Secretary

Luther H. Hodges, Jr., Deputy Secretary

Jordan J. Baruch, Assistant Secretary for Productivity, Technology and Innovation
NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

Issued June 1980

16

258AA XLI

372

Library of Congress Catalog Card Number: 80-600067

National Bureau of Standards Special Publication 577
Nat. Bur. Stand. (U.S.), Spec. Publ. 577, 228 pages (June 1980)

CODEN: XNBSAV

U.S. GOVERNMENT PRINTING OFFICE

WASHINGTON: 1980

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402

Price $6.00
(Add 25 percent additional for other than U.S. mailing)

ABSTRACT

Recommended load factors and load combinations are presented which are compatible

with the loads in the proposed 1980 version of American National Standard A58, Building

Code Requirements for Minimum Design Loads in Buildings and Other Structures.

The load

effects considered are due to dead, occupancy live, snow, wind and earthquake loads.

The

load factors were developed using concepts of probabilistic limit states design which

incorporate state-of-the-art load and resistance models and available statistical information.

Reliabilities associated with representative structural members and elements designed

according to current (1979) structural specifications were calculated for reinforced and

prestressed concrete, structural steel, cold-formed steel, aluminum, masonry and glued

laminated timber construction.

The report presents the rationale for selecting the criterion

format and load factors and describes the methodology to be followed by material specification

groups for determining resistance factors consistent with the implied level of reliability

and the statistical data.

The load factors are intended to apply to all types of structural

materials used in building construction.

Key words:

Aluminum; buildings (codes); design (buildings); concrete (prestressed);

concrete (reinforced); limit states; loads (forces); ma sonry; probability theory;

reliability; safety; specifications; standards; statistical analysis; steel;

structural engineering; timber.

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