With the new KVB-connector, REISSER offers its first lift-off lock with an approval for timber-concrete composite (TCC) ceilings. REISSER highlights that the new general type approval (aBG) of the KVB-connector is the first time that the load-bearing capacity of lift-off locks for TCC constructions, which was previously not clearly regulated, has been regulated for such a fastener.
KVB-connector, equipped with a birdsmouth joint design, creates a shear-resistant bond between the timber component and the concrete slab. These connectors, which are screwed vertically into the timber constructions, are used to absorb tensile forces between the concrete slab and the timber component around the birdsmouth joints. Depending on the structural model, KVB-connectors can be used both inside and outside the birdsmouth joints. As a lift-off lock, they transfer axial tensile loads at right angles to the bond joint between the concrete and wood.
According to the currently valid norms (EC 5), a ceiling with a birdsmouth joint design cannot currently be clearly designed in accordance with the rules because, among other things, EC 5 does not provide any load-bearing capacity values for the head pull-through from the concrete. At the same time, however, the technical specification DIN CEN/TS 19103 (for the next generation of Eurocodes), which has not yet been introduced, requires a lift-off lock. This is why REISSER developed its KVB-connector as a solution.
The aBG contains load-bearing capacity tables to facilitate the design of the lift-off lock. This is because four failure criteria must be analysed, such as pull-out failure of the screws from the timber component, steel tension failure of the screws, conical concrete break-out and pull-out of the screws from the concrete. With the help of the load-bearing capacity values in the tables, the check can be carried out easily without having to recalculate each failure criterion individually.
Up to 6 times higher load-bearing capacity for a minimum number of fasteners
“The embedment depths of the REISSER KVB-connector in wood and concrete guarantee up to six times higher load-bearing capacity compared to conventional pan head screws,” states REISSER. This means the number of lift-off locks is reduced, improving the cost-effectiveness of the birdsmouth joint design.
The KVB-connector is currently available with a diameter of 8mm and in 20mm increments, with lengths from 200mm to 300mm. No additional tools are required when screwing in the REISSER KVB-connectors, which saves time during installation.
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