AbstractIn the past few decades, the use of glass fiber-reinforced polymers (GFRP) to enhance the strength and stiffness of timber beams has been established. Research to predict the performance of structural timber is ongoing. Nondestructive evaluation of its dynamic performance and reliability are important. A nondestructive testing method based on fast Fourier transform analysis was used to establish the dynamic modulus of elasticity of GFRP-reinforced timber beams. The results were compared to those obtained via destructive measurements of the static modulus of elasticity using a regression analysis method. Significant correlations between the dynamic modulus of elasticity (MOE) and static MOE indicate that nondestructive testing is a suitable tool for practical use. Reinforced timber beams were designed based on the measured dynamic MOE. Orthogonal theories were used to analyze the effects of the thickness, glue application, and surface area of GFRP on the MOE of reinforced timber beams. Furthermore, the system reliability of GFRP-reinforced timber beams was predicted with a finite element model. The results showed that GFRP can significantly increase the reliability of structural lumber.