Design for Security with Concrete
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Buildings are designed to resist loads prescribed by building codes.
These include gravity loads such as building weight and live load,
wind, seismic loads and fire. Depending on the building type, configuration,
and location other loads such as water pressure, snow, soil pressure,
rain, and temperature effect may also need to be accounted for.
Explosive
blast, whether accidentally or intentionally caused, is another
force that needs to be taken into account. Blast generally results
in a high-amplitude impulse loading which lasts for a very short
period of time and produces high pressure loading. The loading in
many situations is local in the sense that only those elements closest
to the blast may be directly impacted. Elements far from the blast
site may experience little or no direct impact due to sharp attenuation
(dissipation) of blast energy with distance. The forces experienced
by structural components depend on the size, geometry and proximity
of the explosion. For decades, blast-resistant design was applied
almost exclusively to military facilities. Since the 1995 Oklahoma
City bombing, however, concern for blast resistance has spread to
other sectors as well.
Explosive or other accidents may cause damage to one or limited
number of structural members leading to additional collapse of adjoining
members, which in turn leads to additional collapse. This sequence
of failure is known as progressive
collapse. Following the Alfred P. Murrah Federal Building bombing
in 1995, an executive order was issued by the federal government
to establish construction standards for federal buildings subject
to terrorist attack.
In response to this executive order, several committees and departments
developed criteria for blast-resistance building design The Interagency
Security Committee (ISC) was organized to issued the Security
Design Criteria for New Federal Office Buildings and Major Modernization
Projects. The General Services Administration published Progressive
Collapse Analysis and Design Guidelines for New Federal Office Buildings
and Major Modernization Project in 2000 and revised it in June
2003 to meet the progressive collapse requirements of the ISC. The
U.S. Department of Defense (DoD) created the Unified Facilities
Criteria (UFC) system to provide guidelines for design and construction
of all DoD construction projects and introduced design for progressive
collapse mitigation and prevention. The general planning, layout,
and discussions on different level of protection for building are
discussed in the DoD document; UFC 4010-01 DoD Minimum Antiterrorism
Standard for Buildings. Detailed design for progressive collapse
is introduced in UFC 4-023-03 Design of Buildings to Resist
Progressive Collapse.
The main purpose of structural design for building is to protect
their inhabitants and contents from harm. To achieve this purpose
all possible loads and hazard scenarios during the life time of
the building should be considered. Every building is unique, not
every building faces the same risks, and not every potential threat
justifies the same precautions, but it is important to evaluate
all potential hazard and risks and take appropriate precautions
to promote the safety and security of buildings and the people who
occupy them.
Concrete and Explosive
Blast |
| Concrete has many favorable attributes with regard to blast
response. Blast load durations are very short term compared
to other extreme structural loads, and are often shorter than
the natural period of many structural elements. Because of this
blast waves do not excite the mass of the structure in the same
way as longer period, cyclic loading. The mass of concrete structures
provides a direct resistance to the blast wave. The inherent
continuity of reinforced concrete structures allows properly
detailed structures to respond in a predictable manner, and
also provides a degree of reserve capacity with the potential
to develop alternate load path and resistance mechanisms under
extreme conditions. Properly detailed concrete structures have
substantial ductility and energy dissipation characteristics,
which are necessary to resist blast effect. Also, the potential
for fires from explosions is very high, both from the explosion
itself as well as from secondary fires caused by damage. The
inherent fire resistance of concrete is attractive, particularly
due to the potential of having a compromised fire suppression
system following a blast event. |
| Publications |
NEW!

|
Blast
Resistant Design Guide for Reinforced Concrete Structures
(EB090)
This guide, which includes a foreword by Dr. Gene Corley, provides
structural engineers with a practical treatment of the design
of cast-in-place reinforced concrete structures to resist the
effects of blast loads. Readers will be able to understand the
principles of blast-resistant design, determine the kind and
degree of resistance a structure needs, and specify the materials
and details required to provide it. Guidelines are provided
for detailing requirements for blast resistance and detailing
philosophy and reinforcement splicing are introduced for columns,
beams, slabs, walls and joints. It includes a final chapter
devoted to design methods that can protect structures against
progressive collapse. |
 |
PCA
Notes on ACI 318-08 Building Code Requirements for Structural
Concrete with Design Applications (EB708)
The tenth edition of this classic PCA resource has been updated
to reflect code changes introduced in the latest version of
Building Code Requirements for Structural Concrete,
ACI 318-08. These notes will help users apply code provisions
related to the design and construction of concrete structures.
Each chapter of the manual starts with a description of the
latest code changes. Emphasis is placed on “how-to-use”
the code. Numerous design examples illustrate application of
the code provisions. |
 |
Seismic
Detailing of Concrete Buildings (SP382)
This publication contains a comprehensive summary of the seismic
detailing requirements contained in Building Code Requirements
for Structural Concrete (318-05) and Commentary (318R-05),
which is adopted by reference in the 2006 International
Building Code. A supplemental CD is included with reinforcement
details for beams, columns, two-way slabs, walls and foundations.
|
 |
Simplified
Design: Reinforced Concrete Buildings of Moderate Size and Height
(EB104)
The publication presents timesaving analysis, design, and detailing
methods for reinforced concrete buildings, particularly economical
for buildings with one- to seven-stories. Revised and updated
to ACI 318-02, it incorporates loading calculations and seismic
design provisions in accordance with IBC 2003 and ASCE 7-02. |
 |
An
Engineering Guide to: Concrete Buildings and Progressive Collapse
Resistance (IS545)
The response of reinforced concrete buildings to blast load
is discussed. The U.S. General Services Administration (GSA)
progressive collapse analysis and guidelines are introduced.
The results of a PCA study on applying the GSA method of analysis
to concrete moment resisting frame buildings is presented. The
publication also includes a brief introduction to blast load.
|
 |
Structural
Integrity Requirements for Concrete Buildings (RP436)
Upon reading this reprinted article from Structural Engineer
and completing the quiz to earn CEU credits, the reader will
learn, the reader should be able to understand the structural
integrity requirements for reinforced concrete buildings in
accordance with the American Concrete Institute’s Building
Code Requirements for Structural Concrete (ACI 318-05).
The reader will learn the detailing provisions to achieve structural
integrity for cast-in-place joists, beams, two-way slabs, lift
slabs, and precast concrete construction. |
| Helpful Articles |
U.S.
– GSA Progressive Collapse Design Guidelines Applied to
Concrete Moment-Resisting Frame Buildings
Originally published in 2004 ASCE/SEI Structures Congress
proceedings, Nashville, Tenn. |
Capacity
of Joints to Resist Impact Loads in Concrete Moment-Resisting
Frame Buildings
Originally published in 2007 ASCE/SEI Structures Congress
proceedings, Long Beach, Calif. |
Fire
and Concrete Structures
Originally published in 2007 ASCE/SEI Structures Congress
proceedings, Long Beach, Calif.
|
| New
Engineers Under Fire |
| High-Strength
Concrete and Fire |
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