There are 3 basic types of bollard mountings: fixed, removable, and operable (retractable or fold-down). Fixed bollards may be mounted into existing concrete, or set up in new foundations. Manufactured bollards are frequently created with their 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 for purely aesthetic installations and substantial visual deterrence and direction, but provide only minimal impact resistance.
Bollards designed to control impact are often a part of 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 have better resistance, spreading the impact load spanning a wider area. For sites where deep excavation will not be desirable or possible (e.g. an urban location having a basement or subway under the pavement), bollards made out of shallow-depth installation systems are for sale to both individual posts and sets of bollards. Generally speaking, the shallower the mounting, the broader it must be to resist 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 from the mount to permit access. This technique is meant for locations where the change of access is occasionally needed. It could incorporate a locking mechanism, either exposed or concealed, to prevent unauthorized removal. Both plain and decorative bollards are available for this kind of application. Most removable bollards are certainly not intended for high-impact resistance and 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 could be electric or hydraulic and often add a dedicated backup power installation and so the bollard remains functional during emergencies. Retractable systems tend to be unornamented.
Bollards are as ubiquitous since they are overlooked. They talk to the requirement for defining space, one of many basic tasks in the built environment. Decorative bollards and bollard covers give you a versatile solution for bringing pleasing form to a variety of functions. The plethora of options is vast with regards to both visual style and performance properties. For security applications, a design professional with security expertise should be included in the planning team.
According to Weidlinger Associates principal, Peter DiMaggio – an expert in security design – careful assessment from the surrounding site is required. “Street and site architecture will determine the maximum possible approach speed,” he said. “If you can find no methods to the property with a long term-up, an attack vehicle cannot develop high speed, and also the resistance of the anti-ram barriers may be adjusted accordingly.”
Anti-ram resistance is commonly measured employing a standard created by the Department of State, referred to as K-rating. K-4, K-8 and K-12 each reference the ability to stop a truck of any specific weight and speed preventing penetration in the payload more than 1 m (3 ft) beyond 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 as well as the substrate it’s anchored into.
Videos of bollard crash tests are featured on several manufacturer’s Websites. The truck impacts 2 or 3 bollards at high-speed, as well as the front of the vehicle often crumples, wrapping completely round the centermost post. Part of the cab may fly off the truck, the top 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 often lifted several feet upward. In all successful tests, the payload on the back from the truck fails to pauxnp more than 1 meter beyond the collection 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 a 102-mm (4-in.) pipe, depending on the engineering of the foundation. It is usually full of concrete to boost stiffness, although unfilled pipe with plate stiffeners inside may actually produce better resistance within the same diameter pipe. Without any type of internal stiffening, the pipe’s wall-thickness must be significantly greater. For fixed-type security bollards, simple pipe bollards may be functionally sufficient, if properly mounted. Undecorated pipe-type bollards can also be specially manufactured.