EXPERIMENTAL RESEARCH OF CONTINUOUS WOOD WITH STRUCTURAL DIMENSIONS TAKING INTO ACCOUNT THE MOISTY FACTOR

Abstract

²National University of Water and Environmental Engineering, Rivne

Materials, elements and structures made of wood can be operated in environments with different humidity. Humidity of wood directly affects its strength and deformable properties.

The works of domestic and foreign authors who studied the effect of moisture on the strength and deformability of wood of different species were analyzed in detail. It turned out that there are very few such works. According to these works, it is difficult to detect the effect of moisty on the basic physical and mechanical properties of wood. And they usually concerned the testing of wood under a soft load regime, which does not fully reflect their real stress-strain state.

We have developed a method of experimental studies of various deciduous (birch, alder, ash) and coniferous (larch, pine, spruce) compression along the fibers with a single short-term load under a rigid test mode (by increasing the displacement of the press plate) with different moisture (30%, 21% , 12%). The age of all wood samples was 60 years. Section of prisms 30x30x120mm and grades of wood without defects and damages. The total number of tested samples - 126 pcs.

After conducting experimental research and processing the results, complete diagrams of deformation of wood "σ-u" deciduous (birch, alder, ash) and coniferous (larch, pine, spruce) wood species from the beginning of loading and to the point of ultimate deformation, respectively, at a moisty of 30% , 21%, 12%.

For the first time, critical deformations of different wood species at the corresponding maximum stress at different moisty were obtained experimentally.

It was found that with a decrease in moisty from 30% to 12%, the strength of wood of all species increases. The critical deformations herewith are reduced.