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DOD Protective Design Manuals Have Wide Application PDF

DOD Protective Design Manuals Have Wide Application - PDF (Page 17)
Patrick Lindsey, PE, Protective Design Center, US Army Corps of Engineers, Omaha, NE

Factors such as site selection, building location of the site, use of fences and clear space, as well as vegetation and structural reinforcements are all critical to protecting a building and its occupants from various threats. Incorporating protection into a facility's design is the best way to achieve a desired level of protection at a reasonable cost. Patrick Lindsey of the Protective Design Center summarizes many of the key features and considerations to be accounted for, and introduces the DOD resources available.

The AMPTIAC Quarterly

Volume 6, Number 4

DOD Protective Design Manuals Have Wide Application

Introduction

Many manuals are available within the DOD to aid engineers in the design of facilities subjected to blast loadings from bombs. Facility design in consideration of exterior blast loadings starts with locating a site that is adequate for the facility and level of protection required. The design basis threat (as defined by the installation master planning team) identifies the weapons, tools and tactics that could be used in an attack against the facility. The site or master planners then review the site plan and the design basis threat to determine if the amount of standoff distance that is available can provide a proper level of protection. The planners will then incorporate the use of controlled and non-controlled perimeters, locate appropriate exclusion or non-exclusion zones, define the standoff distances, and identify facility clear zones. They will also locate the facility's entry control points for vehicles and personnel. Should the site be inadequate for a structure built with standard construction techniques, then blast loadings will need to be accounted for to give the facility the same level of protection at the reduced standoff distance.

Background History of Standards

Military Hardened Structures Progression Since the invention of dynamite by Alfred Nobel in 1866, blast effects on structures have been observed. In 1870, Rankine and Hugoniot published their analytical solution to normal shocks in an ideal gas and these relationships have formed the foundation for studying gas dynamics and the interaction of shock waves with structures. It is well known that internal blasts are more damaging than exterior blast effects as the shock and gas pressure combine to act on the structure.

In the last 50 years, the engineering units within the Military developed many mathematical models to capture the structural interaction with blast waves. After World War II, these models started to show development when damage levels for masonry structures we re correlated to crater size, crater location, and explosive weights used in bombing runs. Damage level was a measure of the amount of structure remaining based on the blast pressure and impulse the structure experienced from those bombs. From those early days of the 1950's other observations were noted that relate the many blast parameters to scaling laws, thus making it easy for engineers to develop models for predicting categories of damage based on: weight of explosive, range, and type of structure. The 1950's were also the beginning of the nuclear age, and many design ideas were developed during this era. A lot of the bunker mentality commonly associated with explosive effects came from this time period.

Anybody who has handled explosives knows the dangers associated with that endeavor, as many accidents have occurred as a result of their handling. A vast amount of knowledge was acquired from accident investigations of catastrophic events. To protect personnel, a Tri-Service group from the Army, Navy and Air Force was formed to develop a manual to give engineers a procedure that lets them design "Structures to Resist the Effects of Accidental Explosions" (commonly known as technical manual TM 5-1300). The primary purpose of the manual is to present methods for protective construction used in facilities for the development, testing, production, storage, maintenance, modification, inspection, demilitarization, and disposal of explosive materials. This manual was used as the standard for explosive effects for about thirty years. By using this manual, engineers could design structures to resist the effects of blast waves and fragments preventing the propagation of explosive effects from one structure to the next, or to prevent the mass detonation of explosives and provide protection to personnel and valuable equipment. Instrumental to this approach was a well-developed understanding of:

  • the blast load parameters
  • the response of structures to blast loads
  • how to establish proper details for construction to develop the proper structural response
  • establishing guidelines for siting explosives facilities.

Technical manual TM 5-855-1, "Fundamentals of Protective Design for Conventional Weapons" also came out of the post- World War II era. While this manual is dedicated to the design of structures to resist conventional weapons, during the 1970's great advances were made in the area of numerical modeling of nuclear weapon effects. These include the effects of dynamic response of aboveground, and belowground structures to airblast, blast-induced ground shock, cratering, and the response of various materials to these effects. These modeling techniques were then applied to the conventional weapons arena and the manual has been updated several times since its original printing.

This manual and TM 5-1300 deal with primarily concrete and steel structures, but not everybody works in those types of structures. Additional work has produced more data on how conventional construction responds to blast loads and that data has been incorporated into the new design guidance.

After the Marine barracks bombing in Beirut, Lebanon in 1983, the DOD looked for a group to develop procedures that could be implemented to prevent this type of incident from recurring. The Army established the Corps of Engineers Protective Design Center to take on this mission and its main purpose was to provide physical security and antiterrorism protection to military assets. The first document created by this group was called the Security Engineering Manual, which became the TM 5-853 series of manuals on security engineering. Much of the blast and fragment technology developed for TM 5-1300 and TM 5-855-1 had direct application to the area of security engineering. Within this series of manuals, aggressors, weapons, tools and explosives are defined to develop a design basis threat against specific assets. With this information protective measures are designed to counter these threats and protect the defined assets.

The physical security portion is that part of security concerned with physical measures designed to safeguard personnel; prevent or delay unauthorized access to equipment, installations, material, and documents; and to safeguard against espionage, damage, and theft. Prior to this period, many of the regulations were not interrelated or tied to design procedures, and at times it was difficult to determine what level of protection was being provided for an asset. This manual brought threats and protective measures together as a security engineering design procedure, balancing the design basis threat against the level of protection.

The antiterrorism aspects of facility design are the defensive measures used to reduce the vulnerability of individuals and property to terrorist attacks and often include a limited response and containment of the aggressor by local military forces, or a response force. Therefore, security engineering is the process of identifying practical, risk-managed short and long-term solutions to reduce and/or mitigate dynamic manmade hazards by integrating multiple factors, including construction, equipment, manpower, and procedures.

Continue reading in AMPTIAC Special Issue Quarterly - PDF 68 Pages.

Military Hardened Structures Progression

Application of DOD Manuals to Antiterrorism

Security Engineering Definitions
Controlled Perimeter
Standoff Distance
Level of Protection
Nonexclusive Zones
Clear Zones
Facility Clustering
Lines of Sight
Minimum Measures

Entry Control Points
Approach Road
Visitor and Truck Access Control Center
Entry Control Point
Gates and Barriers

Site Planning
Vantage Points
Minimum Standoff Distances
Unobstructed Space
Railroad Location

Building Layout
Parking Beneath Buildings
Drive-up / Drop Off
Superstructure
Building Location
Asset Location

Also see: Designing Blast Hardened Structures For Military & Civilian Use - PDF, Page 53.

VHSC Very-High-Strength-Concretes For Use In Blast And Penetration-Resistant Structures PDF

Dr. J. Donald Cargile, Impact and Explosion Effects Branch;
Ed F. O'Neil and Billy D. Neeley, Concrete and Materials Division;

Geotechnical and Structures Laboratory, US Army Corps of Engineers, Engineer Research and Development Center, Vicksburg, MS

You may be thinking that there is nothing we can tell you about concrete that won't cure insomnia, but you'd be wrong. How does advanced concrete 4 to 5 times stronger than standard concrete sound? The folks at ERDC are working to drastically improve this ubiquitous material, both in its general compressive strength and its resistance to fragmentation in impact events. Donald Cargile and his colleagues present the experimental data and demonstrate that concrete has a lot of development potential left in it.

VHSC Very High Strength Concretes - PDF, page 61.

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Introduction

Most fixed protective structures employ concrete in some way. The US Army Engineer Research and Development Center (ERDC) is conducting research to provide force protection in everything from foxholes to fixed facilities and against threats ranging from small arms to advanced conventional, and even terrorist weapons. Concrete is a highly economical material, it can be cast into many shapes, and can be formulated for varying degrees of strength and durability. It is primarily used for its compressive strength, as concrete is much stronger in compression than it is in tension. With the proper use of tensile reinforcement, concrete can be used in many tensile-loaded applications, such as flexural members, eccentrically loaded compression members, and direct tension members. Because of the wide use and availability of concrete, it is useful to elaborate on its fundamentals. Additionally, a better understanding of the complex creation of concrete variants will assist engineers and architects in choosing the best materials that address aesthetic, engineering, and protective considerations.

Advantages of Higher Strength Concrete and its Application to Structural Protection

Limitations of Conventional Concrete

VHSC Principles ( Very High Strength Concrete )

Tensile Properties

The tensile strengths of VHSCs can be higher than those of conventional concretes. As mentioned previously, tensile strength of VHSC may nominally be only 10 MPa, while it's compressive strength is on the order of 180 MPa. The addition of steel fibers increases the first-crack load, increases the ultimate load-bearing capacity, and dramatically increases the flex- ural toughness.

Very-high-strength concretes exhibit near-linear stress-strain characteristics up to failure when fabricated without the addi- tion of fibers. Their fracture energy, defined as the area beneath the load-deflection curve, is somewhat less than 140 J/m2.The addition of fibers to the matrix improves the behavior of the concrete in the post-first-crack region of the load-to-failure cycle. In VHSC, various percentages and types of steel fibers have been used but the best overall results (incorporating cost considerations) have been obtained with hooked-ended, steel fibers 30 mm in length and 0.5 mm in diameter. The large number of small fibers which cross the path of potential cracks, coupled with the good bond between fiber and matrix, provide high resistance to fiber pullout during ten- sile-cracking, and greatly increase the toughness of the materi- al. Figure 1 shows the load-deflection curve of a typical VHSC beam. By comparison, a load-deflection curve for a conven- tional concrete and a conventional fiber-reinforced concrete are added. Comparison of the areas under the curves gives a rela- tive relationship for the increase in toughness afforded by the very-high-strength concrete. The greatest effect is in the area of the curve beyond the first-crack load, where the sample's load- deflection behavior transitions from linear to non-linear. Up until this load, the tensile-carrying-capacity of the concrete has been responsible for the shape of the curve. In the unreinforced concrete, the magnitude of the first-crack load is about one- tenth that of the VHSC and the load and deflection of the post-first-crack portion of the curve is very small. Likewise, even with conventional fiber-reinforced concrete the first-crack strength is low er than VHSC and the post-first-crack portionof the curve is also smaller. Toughness is a measure of the amount of energy that must be expended to open cracks in the matrix under tensile loading. An example of toughness would be the resistance to a projectile passing through a material. This toughness is important in the performance of protective structures. The amount of energy required to penetrate the VHSC concrete will be greater than that required to penetrate conventional concrete. This means that some projectiles will be less effective at penetrating the structure, and perhaps will even be stopped by the VHSC. If the projectile completely passes through the VHSC, the exit velocity will be lower than that through the same mass of con- ventional concrete. Also, the amount of material fragmented from the back of a protective-structure member as the projec- tile passes through (also called spall) will be reduced by the steel fibers in the VHSC matrix.

Continue reading: AMPTIAC Advanced Materials & Processes Technology Information Analysis Center - Special Issue Quarterly PDF, 68 Pages.

Underground Buildings : Architecture & Environment : New Book

Underground BuildingsSkyscrapers are the headliners and underground buildings are the virtually unnoticed understudies of architecture.

Every day, tens of thousands Americans use more than 700 public and commercial structures and 5000 private homes that nestle within the earth. Major new subterranean structures are under construction or are on the drawing boards.

Subsurface Buildings explores underground buildings , examines their impact on architecture and the environment, and addresses such questions as;

  1. Why would anyone want to bury a building underground?
  2. Are underground buildings safe?
  3. How do architects feel about designing buildings that are hidden within the earth?
  4. What is the environmental impact of subterranean architecture?

A dozen Subsurface Buildings articles use photo's, drawings, and descriptions to answer questions like these while showing that underground buildings are surprisingly common and appealing.

Author, Loretta Hall

» Hardened Structures : Complete design / build services for all types of underground structures and shelters, including homes. Confidential Client Inquiry

» Underground Buildings: Architecture & Enviroment

Survival Top 50 Blog Article / USAEBN USA Emergency Broadcasting Network

Hardened Structures

Tactics to try and remove you from your home will likely be ineffective if it's fortified by Hardened Structures, a Virginia-based construction company that offers ballistic hardened exteriors, installed on the outer walls and windows of your house. The custom exteriors are built not only to withstand bullets, but also forced entry, biological and chemical agents, and shock from underneath due to bombs going off nearby. Higher-level protection can resist damage from tornadoes, hurricanes and other natural disasters.
Hardened Structures can build a basic fallout shelter for around $40,000. Necessary options such as air filtration and sewage systems cost a little extra, but should be included for anyone serious about surviving indefinitely. Despite being around since 1991, the company is still relatively uknown and maintains a low-profile. It guarantees confidentiality with all projects.
Survival Top 50 Blog Article