Effect of lamina thickness on flexural performance and creep behavior of douglas fir glued laminated timber beam

This research presents the effects of lamina thickness on flexural and creep performances of glulam timber. Flexural test results indicated that nonlinear load-displacement curve could be defined as both exponential and power functions. Lamina thickness was not affected to nonlinear curve, especially at initial linear relationship. Slightly different of 2.92% for nonlinear function parameters was obtained. For flexural creep test due to three levels of sustained load for 1,000 hours, only secondary creep stage behaviors without delamination were observed for all glulam timbers while average relative creep was 1.66. Effect of lamina thickness was also not found for creep performance. Finally, creep models have been developed including Bailey-Norton, adjusted Pickel, simplified Pickel, and Dorn models and found that Bailey-Norton and the adjusted Pickel models gave a good correlation with experiment and were the suitable models which could be used to predict long-term flexural creep behavior for various stress levels.