Secondary Structural Elements - all other load bearing
The following are primary TMs (see Good Engineering
members, such as floor beams, slabs, etc.;
Practice Guidelines, Item 18, in this section for additional
Primary Non-Structural Elements - elements (including
their attachments) which are essential for life safety
Air Force Engineering and Services Center. Protective
systems or elements which can cause substantial injury if
Construction Design Manual, ESL-TR-87-57. Prepared
failure occurs, including ceilings or heavy suspended
for Engineering and Services Laboratory, Tyndall Air
mechanical units; and
Force Base, FL. (1989)
Secondary Non-Structural Elements - all elements not
U.S. Department of the Army. Fundamentals of
covered in primary non-structural elements, such as
Protective Design for Conventional Weapons,
partitions, furniture, and light fixtures.
TM 5- 855-1. Washington, DC, Headquarters, U.S.
Priority should be given to the critical elements that are
Department of the Army. (1986)
essential to mitigating the extent of collapse. Designs for
U.S. Department of the Army. Security Engineering, TM
secondary structural elements should minimize injury
5-853 and Air Force AFMAN 32-1071, Volumes 1, 2, 3,
and damage. Consideration should also be given to
and 4. Washington, DC, Departments of the Army and
reducing damage and injury from primary as well as
Air Force. (1994)
secondary non-structural elements.
U.S. Department of the Army. Structures to Resist the
Loads and Stresses. Where required, structures shall be
Effects of Accidental Explosions, Army TM 5-1300, Navy
designed to resist blast loads. The demands on the
NAVFAC P-397, AFR 88-2. Washington, DC,
structure will be equal to the combined effects of dead,
Departments of the Army, Navy and Air Force. (1990)
live , and blast loads. Blast loads or dynamic rebound may
occur in directions opposed to typical gravity loads.
U.S. Department of Energy. A Manual for the Prediction
of Blast and Fragment Loading on Structures, DOE/TIC
For purposes of designing against progressive collapse,
11268. Washington, DC, Headquarters, U.S.
loads shall be defined as dead load plus a realistic estimate
Department of Energy. (1992)
of actual live load. The value of the live load may be as
low as 25 percent of the code-prescribed live load.
Structural and Non-Structural Elements. To address
blast, the priority for upgrades should be based on the
The design should use ultimate strengths with dynamic
relative importance of a structural or non-structural
enhancements based on strain rates. Allowable responses
element, in the order defined below:
are generally post elastic.
Primary Structural Elements - the essential parts of the
building's resistance to catastrophic blast loads and
progressive collapse, including columns, girders, roof
Revised March 2005 PBS-P100