There are 3 basic types of bollard mountings: fixed, removable, and operable (retractable or fold-down). Fixed bollards can be mounted into existing concrete, or set up in new foundations. Manufactured bollards are frequently made with their very own mounting systems. Standalone mountings can be as non-invasive as drilling into existing concrete and anchoring with epoxy or concrete inserts. Such surface-mounted bollards can be used as purely aesthetic installations and substantial visual deterrence and direction, but provide only minimal impact resistance.
Bollards made to protect against impact are generally embedded in concrete several feet deep, if site conditions permit. Engineering of the mounting depends upon design threat, soil conditions as well as other site-specific factors. Strip footings that mount several bollards provide better resistance, spreading the impact load spanning 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), bollards created using shallow-depth installation systems are accessible for both individual posts and teams of bollards. In general, the shallower the mounting, the broader it should be to face up to impact loading.
A removable bollard typically has a permanently installed mount or sleeve below grade, while the sleeve’s top is flush using the pavement. The mating bollard could be manually lifted out from the mount to allow access. This technique is intended for locations where the change of access is occasionally needed. It could add 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 utilized in anti-ram applications.
Retractable bollards telescope down below pavement level, and might be either manual or automatically operated. Manual systems sometimes have lift-assistance mechanisms to ease and speed deployment. Automatic systems may be electric or hydraulic and quite often add a dedicated backup power installation therefore the bollard remains functional during emergencies. Retractable systems are generally unornamented.
Bollards are as ubiquitous because they are overlooked. They speak to the requirement for defining space, one of many 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 available options is vast in terms of both visual style and performance properties. For security applications, a design professional with security expertise needs to be included in the planning team.
According to Weidlinger Associates principal, Peter DiMaggio – a specialist in security design – careful assessment of the surrounding website is required. “Street and site architecture determines the highest possible approach speed,” he stated. “If you can find no strategies to your building with a long term-up, an attack vehicle cannot build up high speed, as well as the resistance in the anti-ram barriers may be adjusted accordingly.”
Anti-ram resistance is commonly measured using a standard developed by the Department of State, referred to as K-rating. K-4, K-8 and K-12 each refer to the opportunity to stop a truck of any specific weight and speed and stop penetration from the payload more than 1 m (3 ft) past the anti-ram barrier. Resistance depends not merely on the size and strength of the bollard itself, but in addition on the way it is anchored and also the substrate it’s anchored into.
Videos of bollard crash tests are featured on numerous manufacturer’s Web sites. The truck impacts several bollards at high speed, and also the front from the vehicle often crumples, wrapping completely across the centermost post. Portion of the cab may disappear the truck, the front side or rear end could rise several feet inside the air, and front or rear axles might detach. The bollards and their footings are often lifted several feet upward. In most successful tests, the payload on the back of the truck does not pauxnp more than 1 meter past the line of bollards, thus satisfying the typical.
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 their foundation. It is often full of concrete to increase stiffness, although unfilled pipe with plate stiffeners inside may actually produce better resistance in the same diameter pipe. Without any form of internal stiffening, the pipe’s wall-thickness needs to be significantly greater. For fixed-type security bollards, simple pipe bollards may be functionally sufficient, if properly mounted. Undecorated pipe-type bollards are also specially manufactured.