Creep and Creep-Rupture Behavior of Wood-Based Structural Panels

摘要

This paper summarizes a cooperative research program between the USDA Forest211u001eService, Forest Products Laboratory (FPL), in Madison, Wisconsin, and Forintek 211u001eCanada Corp. in Vancouver, British Columbia, Canada. This research program 211u001eprovided detailed creep-rupture and some creep information for composite panel 211u001eproducts. Commercially produced plywood, oriented strandboard (OSB), and 211u001eminimally aligned waferboard were tested to identify nine mills (three for each 211u001eproduct) that produced panels with a range of flexural creep performance. The 211u001ethree plywood, three OSB, and three waferboard products (nine products total, one 211u001efrom each mill) were then tested to provide information on their duration of load 211u001e(DOL) and creep performance. Large panel specimens were subjected to both 211u001erampload and constant-load tests under one environmental condition. The constant-211u001eload results provided conventional or deterministic DOL factors that compared 211u001efavorably with national Design Specifications recommended for adjusting lumber 211u001edesign strength properties under dry service conditions. Ramp-load specimen data 211u001egenerally indicated a lower rate of damage accumulation than did data for 211u001econstant-load specimens. Creep tests at two low constant-load levels were also 211u001eperformed on large specimens under three environmental conditions for a 6-month 211u001eperiod. Those results suggested that present deterministic creep factors in panel 211u001edesign practice might be acceptable for plywood under the influence of relatively 211u001esevere conditions, for OSB in moderate conditions, and for waferboard in dry 211u001eservice environmental conditions.