Screw connection
LENTON coupling system
The slim, safe and cost-effective alternative to the lap joint
The LENTON screw-type coupler from nVent is a mechanical coupler for reinforcing bars featuring a tapered, self-aligning internal thread. The screw connection joins and secures the reinforcing bars together with virtually no slippage. It provides continuous reinforcement and transfers tensile, compressive and dynamic loads like a single bar, regardless of concrete quality, concrete cover or required lap lengths.
The system is available in various designs – as standard, reducing, positioning, combination and welded sleeves, as well as end anchors – and thus covers virtually all typical installation scenarios in reinforced concrete construction.
Typical applications
Where LENTON really shines
LENTON screw-in sleeves are used wherever conventional lap joints reach their limits. Typical applications include shear-transferring joints at wall-to-ceiling and wall-to-beam connections, particularly in sliding and climbing formwork systems. They are suitable for column joints and frame nodes with high reinforcement density, connections between in-situ concrete and precast elements, as well as planned building extensions where sleeve halves are already embedded in the existing structure. Further areas of application include connections of reinforcing steel to steel structures via welded and combination sleeves, as well as end anchors as a compact alternative to end hooks.
Planners & Contractors
For demanding reinforced concrete construction projects
LENTON screw couplers are particularly suitable for structures with high static and dynamic requirements, such as high-rise buildings, bridges, tunnels, power stations and infrastructure projects. Particularly in earthquake-prone regions or in structures subject to significant load reversal, you benefit from the fact that LENTON couplers clearly meet the requirements of common standards for mechanical reinforcement joints (including ACI/IBC Type 1 and Type 2). They demonstrate their strengths where high reinforcement densities, seismic effects, load reversal or concrete spalling occur and flexible connection details are required – for example, in precast elements, building extensions, shear-bearing joints or connections between reinforcing steel and steel structures.
Advantages
Die wesentlichen Vorzüge
- Technology/Function: A tapered, self-aligning thread ensures a virtually slip-free, force-fit connection that behaves like a continuous reinforcing bar, fully transferring tensile, compressive and dynamic loads.
- Design/Installation: Slim couplings, short lengths and simple installation using a torque wrench, resulting in less reinforcement congestion and quick, error-free execution on site.
- Cost-effectiveness/Planning: The elimination of long lap lengths, reduced material usage, smaller component cross-sections and better utilisation of the concrete cover make the solution cost-effective and easy to plan.
Options for every connection scenario
- Standard sleeves for rotating bars of the same diameter.
- Reducing sleeves for connecting bars of different diameters.
- Positioning sleeves, where none of the bars can be rotated (e.g. precast elements, end connections).
- Combination sleeves with metric external thread for connecting steel components to reinforced concrete.
- Weld-on sleeves for connection to steel plates and sections.
- End anchors as a compact alternative to end hooks to simplify reinforcement routing
Load capacity and safety
- 100% Kraftübertragung im Stoß – die Verbindung verhält sich wie ein durchgehender Bewehrungsstab bei Zug, Druck und dynamischer Belastung.
- Tragfähigkeit ist unabhängig von Betongüte und Betondeckung, da die Last direkt von Stab zu Stab übertragen wird.
- Geeignet für seismische Beanspruchung, Lastumkehr und außergewöhnliche Einwirkungen (Explosion, Naturereignisse) und erfüllt/übertrifft u. a. ACI/IBC‑Typ‑1‑ und Typ‑2‑Anforderungen.
- Höhere Schubfestigkeit in Bauteilfugen und verbesserte Dauerhaftigkeit der Stahlbetonkonstruktion.
Design and planning
The conical, self-aligning LENTON thread creates a connection that is both form- and force-locked and virtually slip-free, thereby behaving like a continuous reinforcing bar. The sleeves are very slim and short, so that neither the bar cross-section is reduced nor the concrete cover compromised. This reduces the reinforcement density in the joint area, which improves workability and prevents reinforcement congestion. At the same time, it opens up flexible design options, as straight and bent bars, different steel grades and diameters, as well as combinations thereof, can be connected, and joints can be positioned at virtually any point on the structural element.
On-site installation
- Quick installation: typically around 4.5 turns until hand-tight, then finished with a low torque; standard connections usually take less than a minute.
- No misalignment, as the tapered thread is self-centring; easy alignment of the rods.
- Installation without special tools or a power supply; checking possible with an adjustable torque wrench.
- Plastic protective caps protect the threads, allow for subsequent connection to socket halves already set in concrete and facilitate precast construction.
- Portable threading machines and matching accessories are available as a system solution.
Cost-effectiveness
LENTON screw couplers reduce the need for reinforcing steel, as they eliminate the need for long lap lengths and practically halve the number of bars in the joint area. This allows for smaller cross-sections in structural members, creating additional usable space and reducing formwork and material costs. Simplified planning and very quick installation lead to shorter construction times and lower labour costs. At the same time, you benefit from a globally available, tried-and-tested system solution with a wide range of standard, reducing, positioning, combination and welded sleeves, as well as end anchors, for virtually every connection scenario.
Standards, approvals and quality
- Complies with numerous international standards, e.g. DIN/EN 1992-1-1, ACI 318, ISO 15835, as well as various country-specific regulations.
- Comprehensive building authority approvals in many countries (including DIBt approvals in Germany, ICC-ES/IAPMO reports in the USA).
- Manufactured from high-strength quality steel in ISO 9001-certified plants with tested and documented manufacturing processes.