Security Bollards and Post Covers
The aftermaths of the 1995 Oklahoma City bombing and also the September 11, 2001, attacks saw a sharp surge in the installation of bollards for security purposes. Anti-ram installations include not just posts, but other objects created to resist impact without presenting the appearance of a protective barrier, such as large planters or benches that removable bollards for sale. Once the design threat is determined the resistance necessary to stop it may be calculated. (See ‘Security Design Concepts’ – below). Specification of anti-ram perimeter takes under consideration both the mass and the speed of an approaching attack vehicle, with the latter being considered the more significant.
In accordance with Weidlinger Associates principal, Peter DiMaggio – a professional in security design – careful assessment of the surrounding website is required. “Street and site architecture will determine the utmost possible approach speed,” he stated. “If there are no strategies to your building using a long haul-up, an attack vehicle cannot build up high speed, and the resistance of the anti-ram barriers could be adjusted accordingly.”
Anti-ram resistance is commonly measured using a standard created by the Department of State, called the K-rating. K-4, K-8 and K-12 each reference the opportunity to stop a truck of the specific weight and speed and prevent penetration from the payload a lot more than 1 m (3 ft) beyond the anti-ram barrier. Resistance depends not only on the size and strength from the bollard itself, but also on the way it is anchored and the substrate it’s anchored into.
Videos of bollard crash tests are featured on several manufacturer’s Internet sites. The truck impacts two or three bollards at high speed, and also the front of the vehicle often crumples, wrapping completely around the centermost post. Area of the cab may fly off the truck, the front or rear end could rise several feet inside the air, and front or rear axles might detach. The bollards as well as their footings are sometimes lifted several feet upward. In most successful tests, the payload on the back of the truck will not penetrate more than 1 meter past the collection of bollards, thus satisfying the conventional.
The most basic security bollard is a piece of 203-mm (8-in.), 254-mm (10-in.), or 305-mm (12 in.) carbon steel structural pipe. Some impact resistance is achieved even with a 102-mm (4-in.) pipe, depending on the engineering of its foundation. It is usually filled with concrete to improve stiffness, although unfilled pipe with plate stiffeners inside may actually produce better resistance in the same diameter pipe. Without any kind of internal stiffening, the pipe’s wall-thickness needs to be significantly greater. For fixed-type security bollards, simple pipe bollards might be functionally sufficient, if properly mounted. Undecorated pipe-type bollards can also be specially manufactured.
The greatest downside of a plain pipe is aesthetics. A bit of painted pipe fails to truly blend into – significantly less enhance – most architectural schemes. However, this is often overcome by a decorative bollard cover. Many standalone bollards which do not have impact-resistance that belongs to them are made with alternative mounting capability to slip over standard pipe sizes, forming a beautiful and architecturally appropriate impact-resistance system. These decorative covers can be accessible to enhance specially engineered (but non-decorative) pipe-type bollards.
Security Design Concepts
Much of modern security design focuses on the threat of bomb attacks. The most significant element in protecting against explosions will be the distance involving the detonation and also the target. The force of the blast shockwave diminishes as a purpose of the square from the distance. The greater distance that may be placed between the detonation as well as the protected structure – known as standoff distance – the higher the threat resistance or, conversely, the less blast resistance needs to be included in the structure. Therefore, creation of secure perimeter is the first step in the overall design of blast resistance.
Standoff is valuable architecturally because it allows a building to get protected with out to resemble a bunker. Additionally, it has economic impact, since it is frequently less costly to create standoff rather than bomb-proof the structure itself. Security bollards and other anti-ram installations are made and positioned to create standoff by thwarting the delivery of explosives near to the target by way of a vehicle.
Any security design depends on an estimate of the dimensions of threat to become resisted – the ‘design threat.’ The force of the explosion which can be expected is directly related to the body weight- and volume-carrying capabilities of the delivery vehicle. Explosives are measured with regards to tonnes of trinitrotoluene (TNT). The most potent molecular explosives such, as Composition 4 (i.e. C-4), are approximately another stronger than TNT, whereas a fuel and fertilizer bomb – like was utilized in Oklahoma City – is much less powerful than TNT. Reasonable approximations can be created about how much explosive power can be delivered by a person carrying a backpack, a passenger vehicle, a pickup truck, a flatbed truck, etc. according to the weight-and volume-carrying capacity.
You will find three basic kinds of bollard mountings: fixed, removable, and operable (retractable or fold-down). Fixed bollards could be mounted into existing concrete, or placed in new foundations. Manufactured bollards are frequently created with their particular mounting systems. Standalone mountings could be as non-invasive as drilling into existing concrete and anchoring with epoxy or concrete inserts. Such surface-mounted bollards can be used purely aesthetic installations and substantial visual deterrence and direction, but provide only minimal impact resistance.
Bollards designed to control impact are usually baked into concrete several feet deep, if site conditions permit. Engineering in the mounting is dependent upon design threat, soil conditions along with other site-specific factors. Strip footings that mount several bollards have better resistance, spreading the impact load over a wider area. For sites where deep excavation is not desirable or possible (e.g. an urban location using a basement or subway underneath the pavement), stainless bollard created using shallow-depth installation systems are available for both individual posts and sets of bollards. In general, the shallower the mounting, the broader it must be to resist impact loading.
A removable bollard typically features a permanently installed mount or sleeve below grade, while the sleeve’s top is flush using the pavement. The mating bollard can be manually lifted out from the mount to allow access. This etxxdy is meant for locations in which the change of access is occasionally needed. It may incorporate a locking mechanism, either exposed or concealed, to avoid unauthorized removal. Both plain and decorative bollards are available for this type of application. Most removable bollards are certainly not intended for high-impact resistance and therefore are usually not found in anti-ram applications.
Retractable bollards telescope down below pavement level, and may be either manual or automatically operated. Manual systems sometimes have lift-assistance mechanisms to help ease and speed deployment. Automatic systems might be electric or hydraulic and often add a dedicated backup power installation so the bollard remains functional during emergencies. Retractable systems are generally unornamented.
Bollards are as ubiquitous because they are overlooked. They talk to the requirement for defining space, among the basic tasks from the built environment. Decorative bollards and bollard covers give you a versatile solution for bringing pleasing form to a variety of functions. All the different options is vast in terms of both visual style and satisfaction properties. For security applications, a design professional with security expertise needs to be within the planning team.