Effect of service temperature on shear strength of Pinus wood for roof structures

Resumo

 

Temperature in timber roof trusses structures can reach 60°C and significantly affect wood strength, compromising the structural mechanical performance. This study aimed at quantifying the influence of exposure time to the mentioned temperature in wood strength by monitoring shear parallel to grain (f_v0) of Pinus taeda and Pinus elliottii from planted forests. Exposure times at 60°C, in controlled oven, consisted of zero, 168, 456 and 720 hours. ANOVA results indicated that temperature (60°C) influences significantly, in the four exposure times, f_v0 for both Pinus wood species. For Pinus taeda, slightly more resinous, strength in shear parallel to grain presented successive reductions, related to reference condition (zero hour) for exposure times 168 and 456 hours; and increase for 456 hours to 720 hours. Different behavior was observed for Pinus elliottii, where f_v0 successively showed increases from reference condition for the other temperatures. Even with varied behavior of Pinus wood referring to the influence of exposure times at temperature 60°C, shear strength was significantly affected.