Predicting Creep of Nailed Lumber‐to‐Plywood Joints

Abstract

Data on creep behavior of nailed joints between lumber and sheathing are essential to improve the design of light‐frame wood buildings. Two theoretical models were developed to predict creep of joints under variable loads from test data on creep under constant loads. The models incorporated the strain‐hardening principle and the modified superposition principle; the latter was further modified to include plastic creep in nailed joints. Tests were conducted to develop specific models for nailed joints between Douglas‐fir lumber and plywood. The experimental data for three constant‐load functions were used to formulate the specific models, and the data for four stepwise load functions were used to assess the accuracy of those models. Predicted and experimental data agreed closely for all solutions, but the simplest and most accurate predictions were based on the modified superposition principle. Thus, the models can provide accurate estimates of stiffness loss under long‐term loads in nailed wood components of light‐frame wood buildings.