Guide Specifications for Internal Redundancy of Mechanically-Fastened Built-Up Steel Members - AASHTO

Abstract

GENERAL

These provisions shall be used for the evaluation of internal redundancy in built-up members traditionally designated as Fracture Critical Members (FCM).

These provisions shall be used during the design of new members or the evaluation of existing members built-up from plates and rolled shapes that are mechanically fastened using high-strength bolts or rivets and subject to flexure or axial tension.

Members satisfying the requirements of these provisions shall be considered to possess sufficient internal redundancy to provide safety against complete brittle fracture of the entire member, in the event sudden fracture of an individual tension load-carrying component occurs.

Such members shall be classified as Internally Redundant Members (IRMs).

In new designs, IRMs shall be identified on the contract plans.

A member shall be considered to be in the faulted state when any single tension load-carrying component of the built-up member, e.g., a single angle, cover plate, or an individual component of an axial member, is assumed to be completely severed