DEVICES FOR IMPROVING THE FLEXURAL STRENGTH OF WOOD BEAMS

摘要

Use is made of the tensioning of a steel cable to reduce the sag either of beams of young conifers or of installed beams which have become weak by an overload or xylophagous attack. In the first case, the steel cable (wires) follows, along one groove (8) the length of the beam, goes through it to the left (4-5) and to the right (1-2) at 45 % and is finally tensioned at its extremities (1 and 5) thereby effectively prestressing the beam. In the second case, a hanging clamp (8) with a support (10) is arranged perpendicularly to the beam and passes by the plane of the gravity center of the beam and of its load. On either side of the metal hanging clamp (8) and of its support (10), two cables (2-1, 5-6) are tensioned along one path embracing the beam at both its ends. The tensioning is carried out by means of screwing tie rods (11 and 12) so as to bring the mechanical sag of the assembly back at a desired level and compatible with the diameter of the steel cables.