Comprehensive approach to ensure durabilty of external wooden structures

The article deals with durability of wood, durability of wooden structures and surface modification of wood. We are trying to eliminate the factors causing degradation of wood with the use of photocatalytic materials. Those materials are efficient UV absorbers and they are able to destroy biological aggressors also. The planar particles of titanium oxide TiO2 were chosen for the purpose of our research and applied on a wooden surface. In our case, we used a water solution of TiO2. The main goal of our work was to study the interaction between planar particles of TiO2 and wood matter. The samples of pine wood (Pinus sylvestris) were monitored for 255 days and subsequently evaluated using an electron microscope. The use of TiO2 was compared with reference material and a reference commercial coating.

Ratio analysis between compression and shearing of 72 Brazilian wood species

The Brazilian standard ABNT NBR 7190 (1997) governs the premises for the wood structure sizing through a table and the simplified method. Thus, this research aims to analyze whether the simplified method shown in the standard matches the resistance values of 72 Brazilian species, separated from class C20 to C60. In the end, it was possible to conclude that the value displayed by the standard between the ratio of shear and compression in the direction parallel to the fibers is half of what actually happens in Brazilian species, showing an urgent review in the standard premises.

Strength and displacement under tension and compression of wood joints fastened with nails and screws for use in trusses in Costa Rica

The objective of the present study is to determine the behaviour of two typical types of fastener (nails and screws) used in trusses made of Gmelina arborea and Hieronyma alchorneoides timber. Wood joints with metal fasteners (nails and screws) and five angles (0°, 30°, 45°, 60° and 90°) were subjected to tension and compression loads in order to establish values of displacement in relation to applied loads, strength, stiffness values, mode of failure and a model for prediction of stiffness for intermediate orientations. Results indicate that the differences in loads and displacements appear among species in the compression test, whereas those differences appear among fasteners in the tension test. The results obtained for stiffness indicate that jointsofH. alchorneoides wood present the highest values. Models for prediction of stiffness for truss joints of intermediate orientations were: in compression, while for tension the model was.