BSF is a corbel free system and consists of three parts:

• Beam unit: Cast into the concrete beam and must be anchored with specified anchoring reinforcement.
• Beam-column unit: Cast into the concrete beam and must be anchored with specified anchoring reinforcement.
• Knife: Connect the beam to the column. This is made of solid steel and forms the part of the connection that transfers the load from the beam to the column. Before beam assembly, the knife is retracted and hidden inside the beam unit.

All parts are made of steel. The three main components are in steel grade S355. Threaded rods are quality 8.8, and stop washers are in steel quality S355.

Design principles
When deployed, the sliding knife cantilevers from the beam into the column. It bears onto the base of the column box at the free end, which induces rotation of the knife. This is resisted by bearing against half-round bearing blocks in the beam (see below). These half-round blocks in turn bear against reinforcement which is not shown in the diagram, but is dealt with later in the guide.