Lumber Production for Construction from Round Timber with Heart Rot

Coniferous lumber is popular in low-rise wooden house construction. However, the condition of round timber for lumber production has been going down in recent years. Timber with heart rot is very common nowadays. As a rule, the heart rot removal occurs in harvesting of round timber. At the same time, disease-free sap wood is removed together with the wood affected by the rot in timber cutting. Therefore, a large amount of sound timber remains in forest. Cutting of timber with rot reduces the yield of lumber for construction, as far as rot's presence in building structures is not allowed. A method of cutting round timber with heart rot is proposed for the purposes of production I-beams from solid wood. It is necessary to know the form and sizes of rot for high-quality rough ripping of round timber with heart rot. The relationship between the cross-sectional dimensions of round timber and heart rot along the length of assortments is quite accurately described by the equations of correlative (allometric) growth. The schemes of cutting round timber with heart rot have been developed taking into account these dependencies. Cutting was carried out by split-pith sawing scheme. Firstly, two four-side edged cants with heart rot in the central part of one of the cross-section layers were produced. Then the beams were longitudinally divided into two parts. Rot was removed from these parts by milling Angle bars for I-beams production were obtained as a result of conditional cutting of pine round timber. The studies of the I-beam made of angle bars were carried out. The calculated stresses of beam bending do not exceed the accepted values. The useful output of such bars made of round timber with heart rot is calculated. It has been found that the method of manufacturing elements of building constructions from round timber with heart rot will allow to use them in low-rise wooden house construction. This will expand the wood resources for construction.