Deformation and Creep Recovery of Structural Timber Elements

The use of reinforcement in timber beams has been shown to improve the short-term flexural behaviour but the long-term behaviour is often more complex, particularly when subjected to a variable climate condition. In this study, the creep deflection behaviour of unreinforced and Basalt Fibre Reinforced Polymer (FRP) reinforced beams are subjected to creep tests at a common maximum compressive stress of 8 MPa over a 450-week (≈ 8.5 years) period. This study builds upon data previously presented by the authors for a test period of 75 weeks. Furthermore, the tested elements are unloaded, and the creep recovery data is also presented. Results demonstrated a significant reduction in total creep deflection due to the FRP reinforcement in both a variable and constant climate. Once unloaded, the results indicate that a significant proportion of creep can be recovered when subjected to a constant climate, however, when subject to a variable climate, there appears to be a significant proportion of non-recoverable deformation.