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RE: journalist query - factors of safety

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This safety factor is of interest for comparison, but I would clarify the following:
1. ASCE 7 applies to "buildings and other structures that are subject to building code requirements".  (It does not apply to levees.)
2. ASCE 7 load combinations are to be used "for proportioning elements" of the structure and are to be used with "design specifications for conventional structural materials".  I do not see the load factors in these load combinations as being applicable to factors of safety for global stability issues such as sliding, overturning, flotation, slope stability, etc. For example, IBC requires a factor of safety of 1.5 against sliding and overturning for retaining walls - I would not apply 0.6D to such stability calculations.

William C. Sherman, PE
(Bill Sherman)
CDM, Denver, CO
Phone: 303-298-1311
Fax: 303-293-8236
email: shermanwc(--nospam--at)


From: Khashayar (Casey) Hemmatyar [mailto:khemmatyar(--nospam--at)]
Sent: Friday, November 04, 2005 3:01 PM
To: seaint(--nospam--at)
Subject: re: journalist query - factors of safety

Based on ACSE 7-02 a minimum safety factor of 1.67 (1/0.6) has to be achieved:


ACSE 7-02;

Section 2.4.1 Basic Load Combinations. (ASD)

7.             0.6D + W + H

8.             0.6D + 0.7 E + H


H = load due to lateral earth pressure, ground water

pressure, or pressure of bulk materials;




Khashayar (Casey) Hemmatyar, PE