Creep behaviour and creep recovery of FRP reinforced 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 were subjected to creep tests at a common maximum compressive stress of 8 MPa over a 450-week (≈ 8.5 years) period. This study built upon data previously presented by the authors for a test period of 75 weeks. Furthermore, the tested elements were unloaded, and the creep recovery data was also presented. A significant reduction in total creep deflection due to the FRP reinforcement was observed in the results obtained 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.