Interlayer Influence on Timber-LWAC Composite Structures with Screw Connections

Abstract

Timber-concrete composite structures are often used as upgrade solutions for existent timber floors. The timber cross section is maintained and a concrete layer is poured over the floorboard surface. Floorboards help with loading distribution on the beams. The study presented is based on laboratory tests that used specimens made with a lightweight aggregate concrete (LWAC). The use of this type of concrete, compared with normal weight concrete (NWC), has the advantage of lower dead weights, and might be very important in many cases, namely, when the supporting structure has limited strength. Many design works of timber-concrete composite connections do not take into account the timber interlayer, which is known to reduce the load-carrying capacity and the stiffness of the connection. Previous investigations of NWC found that the inclusion of the interlayer leads to average reductions of 30% and 50% for the load capacity and slip modulus, respectively. The current investigation with LWAC found that such reductions are up to 10 and 30%, respectively.