There are 3 basic varieties of bollard mountings: fixed, removable, and operable (retractable or fold-down). Fixed bollards may be mounted into existing concrete, or installed in new foundations. Manufactured bollards are often designed with their particular 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 designed to control impact are often baked into concrete several feet deep, if site conditions permit. Engineering from the mounting is dependent 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 over a wider area. For sites where deep excavation is not desirable or possible (e.g. an urban location having a basement or subway under the pavement), bollards created using shallow-depth installation systems are available for both individual posts and teams of bollards. In general, the shallower the mounting, the broader it must be to face up to impact loading.
A removable bollard typically has a permanently installed mount or sleeve below grade, as the sleeve’s top is flush with the pavement. The mating bollard may be manually lifted out of the mount to allow access. This technique is supposed for locations where the change of access is occasionally needed. It can add a locking mechanism, either exposed or concealed, to stop unauthorized removal. Both plain and decorative bollards are accessible for this type of application. Most removable bollards are certainly not created for high-impact resistance and they are usually not utilized in anti-ram applications.
Retractable bollards telescope down below pavement level, and could be either manual or automatically operated. Manual systems sometimes have lift-assistance mechanisms to ease and speed deployment. Automatic systems might be electric or hydraulic and quite often add a dedicated backup power installation therefore the bollard remains functional during emergencies. Retractable systems are usually unornamented.
Bollards are as ubiquitous since they are overlooked. They speak with the requirement for defining space, one of the basic tasks from the built environment. Decorative bollards and bollard covers give you a versatile solution for bringing pleasing form to a number of functions. All the different options is vast with regards to both visual style and gratification properties. For security applications, a design professional with security expertise should be contained in the planning team.
According to Weidlinger Associates principal, Peter DiMaggio – an expert in security design – careful assessment from the surrounding website is required. “Street and site architecture determines the utmost possible approach speed,” he stated. “If you will find no strategies to your building using a long run-up, an attack vehicle cannot build up high-speed, and the resistance in the anti-ram barriers can be adjusted accordingly.”
Anti-ram resistance is often measured employing a standard developed by the Department of State, known as the K-rating. K-4, K-8 and K-12 each refer to the opportunity to stop a truck of a specific weight and speed preventing penetration from the payload greater than 1 m (3 ft) past the anti-ram barrier. Resistance depends not only on the size and strength of the bollard itself, but in addition on the way it is anchored as well as the substrate it’s anchored into.
Videos of bollard crash tests are featured on several manufacturer’s Web sites. The truck impacts two or three bollards at high speed, and also the front in the vehicle often crumples, wrapping completely across the centermost post. Portion of the cab may disappear the truck, the front or rear end could rise several feet in 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 from the truck fails to pauxnp greater than 1 meter past the line of bollards, thus satisfying the conventional.
The simplest security bollard is a bit of 203-mm (8-in.), 254-mm (10-in.), or 305-mm (12 in.) carbon steel structural pipe. Some impact resistance is achieved despite having a 102-mm (4-in.) pipe, depending on the engineering of their foundation. It is often filled with concrete to boost 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 must 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.