Precast concrete highway barriers ;are the go-to product for vehicular and construction worker safety, in addition to building security. Precast concrete barriers have the unique ability to not only realign stray vehicles but also reduce their speed. Upon impact, precast concrete barriers partially lift the stray vehicle off the pavement, which decreases the lateral resistance force between tires and pavement. Precast barriers can be installed in permanent or temporary applications.
What are the advantages of having corrugation in crash barriers?
The layout of corrugated beam barriers ;is that the beams are corrugated in the longitudinal direction so that it provides higher lateral stiffness with a thinner material. Moreover, the distance between beams posts and crashing vehicles are considerably increased.
In case the beam barriers are tensioned, it is intended to create a stiff beam erected on relatively weak posts. During vehicle collision, the posts would be separated from the beams and there would be lesser deceleration experienced by the vehicles.
Guardrail Offset Blocks and Associated Products
Features and Benefits
Environmentally safe and eco-friendly, Mondo guardrail blocks ;are made from post-consumer/post-industrial material diverted from the solid waste landfill.
All guardrail blocks are recyclable; there are no disposal costs for damaged blocks because they can be collected, returned, and recycled.
The Mondo block is crash tested to NCHRP Report 350 Standards, Test Level 3-11, and is approved by the Federal Highway Administration.
Lightweight and with a smooth bolt hole, the Mondo block is easier to install.
Material composition is recycled polyethylene, one of the toughest polymers available in the market.
Long-lasting, Mondo blocks are weather resistant and impervious to boring insects.
UV protection is added during manufacturing to extend service life.
Guardrail End Terminal with Outstanding Properties and Different Types
Guardrail terminal end ;not only can be divided into the roadside terminal and median terminal according to their install positions but also can be classified into round end terminal and fish end terminal according to their shape. End terminals are all processed through antiseptic treatment, such as galvanizing and plastic coating, which have superior properties.
1. Low cost, long service life.
2. High safety performance and high intensity.
3. Anti-corrosion, anti-aging, impact resistance.
4. Easy to install, elegant appearance.
End terminals are usually installed on the roadside barriers and median barriers. The end terminal is fixed on the end of the roadside barrier. The round end terminal makes the guardrail an elegant appearance, which has high intensity and is easy to install. W-beam fish end guardrail fixed on the bridge to protect pedestrian safety. Fish end terminals possess high-quality impact resistance.
Square Head Bolts
Square head bolts ;are used in applications where visibility is limited but durable fastening is required. These bolts have large, flat sides and are easy to tighten with a wrench. Square heads are best used in tight or dark spaces where a machinist or fabricator must tighten the bolt blind. It is simple to fit a tool over the square shape even when there are no visual markers available.
Steel Grade 5 Square Head Bolts
Grade 5 medium-strength square head bolts are used in applications where visibility is limited but durable fastening is required. These bolts have large, flat sides and are easy to tighten machinery and equipment with a wrench. Grade 5 steel hex head screws are marked with three radial lines. Square heads are best used in tight or dark spaces where a machinist or fabricator must tighten the bolt blind. It is simple to fit a tool over the square shape even when there are no visual markers available. These bolts come in a black oxide finish, which is corrosion resistant in dry environments, or are zinc-yellow coated for corrosion resistance in wet environments.
Anchor bolts ;are used to connect structural and non-structural elements to concrete. The connection can be made by a variety of different components: anchor bolts (also named fasteners), steel plates, or stiffeners. Anchor bolts transfer different types of load: tension forces and shear forces.
A connection between structural elements can be represented by steel columns attached to a reinforced concrete foundation. A common cause of a non-structural element attached to a structural one is the connection between a facade system and a reinforced concrete wall.
A cast-in-place anchor bolt
The simplest – and strongest – form of anchor bolt is cast-in-place, with its embedded end consisting of a standard hexagonal head bolt and washer, 90-bend, or some sort of forged or welded flange (see also stud welding). The last is used in concrete-steel composite structures as shear connectors. Other uses include anchoring machines to poured concrete floors and buildings to their concrete foundations. Various typically disposable aids, mainly of plastic, are produced to secure and align cast-in-place anchors prior to concrete placement. Moreover, their position must also be coordinated with the reinforcement layout. Different types of cast-in-place anchors might be distinguished:
For all the types of cast-in-place anchors, the load-transfer mechanism is the mechanical interlock, i.e. the embedded part of the anchors in concrete transfers and the applied load (axial or shear) via bearing pressure at the contact zone. At failure conditions, the level of bearing pressure can be higher than 10 times the concrete compressive strength, if a pure tension force is transferred. Cast-in-place type anchors are also utilized in masonry applications, placed in wet mortar joints during the laying of brick and cast blocks (CMUs).
Post-installed anchors can be installed in any position of hardened concrete after a drilling operation. A distinction is made according to their principle of operation.
A wedge anchor
The force-transfer mechanism is based on a friction mechanical interlock guaranteed by expansion forces. They can be furtherly divided into two categories:
The force-transfer mechanism is based on a mechanical interlock. A special drilling operation allows the creation of a contact surface between the anchor head and the hole's wall where bearing stresses are exchanged.
Bonded anchors ;
The force-transfer mechanism is based on bond stresses provided by binding organic materials. Both ribbed bars and threaded rods can be used and a change of the local bond mechanism can be appreciated experimentally. In ribbed bars, the resistance is prevalently due to the shear behavior of concrete between the ribs whereas for threaded rods friction prevails (see also anchorage in reinforced concrete). Bonded anchors are also referred to as adhesive anchors[ or chemical anchors. The anchoring material is an adhesive (also called mortar) usually consisting of epoxy, polyester, or vinyl ester resins. The performance of this anchor's types in terms of 'load-bearing capacity, especially under tension loads, is strictly related to the cleaning condition of the hole. Experimental results showed that the reduction of the capacity is up to 60%. The same applies also to the moisture condition of the concrete, for wet concrete the reduction is 20% using polyester resin. Other issues are represented by high-temperature behavior and creep response.
The force-transfer mechanism of the screw anchor is based on concentrated pressure exchange between the screw and concrete through the pitches.
Their force-transfer mechanism is similar to mechanical expansion anchors. A torque moment is applied to a screw that is inserted in a plastic sleeve. As the torque is applied the plastic expands the sleeve against the sides of the hole acting as an expansion force.
They act by transferring the forces via mechanical interlock. This fastening technology is used in steel-to-steel connections, for instance, to connect cold-formed profiles. A screw is inserted into the base material via a gas-actuated gas gun. The driving energy is usually provided by firing a combustible propellant in powder form. The fastener's insertion provokes the plastic deformation of the base material which accommodates the fastener's head where the force transfer takes place.