One of the way to bridge large spans are timber beam using sloped shear keys. The beam is
composed of two beams with rectangular cross – section, which are located one on the other.
Both beams have made notches for keys and holes for screws. Beams are bending loaded in
the direction opposite from useful load. In this state are beams connected with keys and
screws, which hold preload bending. With keys and screws we keep preload bending, which
help to bending reduction and increase load capacity. With preloading and added useful load,
we providing uniform distribution of tension according to section, which is better in
comparison with monolithic beam because, there is not tension peaks. Also in beam we
reduce bending deflection, which is good because in large spans occur big bending
deflection, which is visually annoying. Mentioned stress state which occur in beam, we gain
from numerical model in program Abaqus. Validation of numerical model is performed with
experimetal three point bending test, which includes the same beam in reality.