Accelerated creep testing of tensile properties of glued laminated bamboo

The tensile creep behavior of glued laminated bamboo was experimentally studied by the conventional creep test with a time duration of 500 h. The Findley creep model was used to fit the creep curves. The accelerated test using the stepped isothermal method (SIM) was applied to characterize the long-term tensile behavior of glued laminated bamboo. The SIM master curves display the creep characteristics of several decades beyond the test duration. The results show that the tensile creep curve of glued laminated bamboo has two stages under different stress levels: The primary and the secondary creep stages. The tensile creep behavior of glued laminated bamboo conforms to linear viscoelasticity, and its creep deformation is proportional to the stress level at any time. When the stress level is high (reaching 60% of the ultimate strength), the glued laminated bamboo undergoes creep fracture, presenting a brittle failure mode. The Findley creep model can well fit the short-term tensile creep behavior of glued laminated bamboo, and its extrapolation agrees well with the SIM creep master curve. Based on the test results and analysis, the isochronous stress-strain curves were established. The coefficient of elastic modulus of laminated bamboo for different design service life was further discussed and compared with the recommended values in GB/T 50005—2017 standard for design of timber structures.