Shear creep and mechanosorptive behavior of nail-plate-jointed laminated-veneer lumber

Abstract

The objective of this research was to evaluate the mechanosorptive deflection of shear creep of nail-plate-jointed laminated-veneer lumber. The joint was composed of steel gusset and nails, 40 mm in length and 2.8 mm in diameter (Zn40). The specimens were loaded parallel (PA) and perpendicular (PE) to the grain. Shearing loads applied were 50 and 100kgf, and the load levels were 11% and 22% (PA) and 7% and 14% (PE) of the maximum strength obtained from static testing. The creep test specimens were loaded for 1500h. A few general conclusions could be drawn from this study: The mechanosorptive deflection (σ_ms) is defined as σ_ms = σ_t — (σ_c + σ_sh) — σ_o, where σ_t, is total deflection, σ_c is pure creep, σ_sh is shrinkage-swelling behavior, and σ_o is the initial deflection. Changes in relative humidity may cause more severe creep deflection than constant humidity, especially during the drying process. The mechanosorptive deflection is greater at the lower load level than that at the higher load level. The mechanosorptive effects seem to be somewhat more resistant in the parallel direction than in the perpendicular direction.