Long-Term Bending Behaviour of Prestressed Glulam Bamboo-Wood Beam Based on Creep Effect

Abstract

: Creep is an important characteristic of bamboo and wood materials under long-term loading. This paper aims to study the long-term bending behaviour of prestressed glulam bamboo-wood beam (GBWB). For this, 14 pre-stressed GBWBs were selected and subjected to a long-term loading test for 60 days. Then, a comparative analysis was performed for the effects of pretension values, the number of pre-stressed wires, and long-term load on the stress variation of the steel wire and the long-term de fl ection of the beam midspan. The test results showed that with the number of prestressed wires increasing, the total stress of the steel wire in the beam midspan and the ratio of the long-term de fl ection to the total de fl ection decreases decreased, but when the number of steel wires exceeded 4, the total stress and long-term de fl ection was less in fl uenced; with the pre-tension value increasing, the ratio of the total stress of the steel wire in the beam midspan and the ratio of the long-term de fl ection to the total de fl ection also decreased, but when the prestress force was greater than 3.975 kN, the total stress and long-term de fl ection were less affected; with the other parameters unchanged, when the value of the long-term load increased, the total stress of the steel wire decreased, and the long-term de fl ection of the beam midspan increased, which shall be more signi fi cant with the long-term load greater than 30% of the standard ultimate bearing capacity. After the test, the experimental data were fi tted, and the creep coef fi cient was given. Finally, the long-term stiffness calculation formula of the pre-stressed GBWB based on creep effect was proposed. The research fi ndings have certain theoretical signi fi cance and engineering value.