There are three basic kinds 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 usually created 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 purely aesthetic installations and substantial visual deterrence and direction, but provide only minimal impact resistance.
Bollards designed to control impact are generally embedded in concrete several feet deep, if site conditions permit. Engineering from the mounting depends upon design threat, soil conditions and 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 with a basement or subway underneath the pavement), bollards created using shallow-depth installation systems are accessible for both individual posts and groups 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, while the sleeve’s top is flush with all the pavement. The mating bollard can be manually lifted out of the mount to allow access. This method is intended for locations where the change of access is occasionally needed. It may include a locking mechanism, either exposed or concealed, to stop 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 are usually not used 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 help ease and speed deployment. Automatic systems might be electric or hydraulic and quite often incorporate a dedicated backup power installation so the bollard remains functional during emergencies. Retractable systems are usually unornamented.
Bollards are as ubiquitous as they are overlooked. They talk to the requirement for defining space, one of the basic tasks in 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 available options is vast with regards to both visual style and performance properties. For security applications, a design professional with security expertise needs to be within the planning team.
Based on Weidlinger Associates principal, Peter DiMaggio – a professional in security design – careful assessment in the surrounding site is required. “Street and site architecture determines the maximum possible approach speed,” he stated. “If you will find no methods to the building having a long haul-up, an attack vehicle cannot develop high speed, as well as the resistance in the anti-ram barriers can be adjusted accordingly.”
Anti-ram resistance is commonly measured using a standard created by the Department of State, referred to as K-rating. K-4, K-8 and K-12 each make reference to the opportunity to stop a truck of any specific weight and speed preventing penetration of the payload greater than 1 m (3 ft) beyond the anti-ram barrier. Resistance depends not only on the size and strength in the bollard itself, but additionally on the way it really 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 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 fly off the truck, the top or rear end could rise several feet in the air, and front or rear axles might detach. The bollards and their footings are sometimes lifted several feet upward. In all successful tests, the payload on the back of the truck will not pauxnp a lot more than 1 meter beyond the line of bollards, thus satisfying the conventional.
The simplest 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 despite having a 102-mm (4-in.) pipe, depending on the engineering of their foundation. It is usually filled with concrete to boost stiffness, although unfilled pipe with plate stiffeners inside could possibly produce better resistance within 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 may be functionally sufficient, if properly mounted. Undecorated pipe-type bollards can also be specially manufactured.