Research On Long Term Deformation Behavior Of Bamboo-based Component

Recombinant bamboo also known as Glued laminated bamboo, is a new type of bamboo material. It has obvious hygroscopicity and long-term creep properties, and its dry shrinkage and wet expansion and long-term creep have a significant impact on the overall mechanical structure performance and normal safe use. At present, research on shrinkage and wet expansion and creep properties of recombinant bamboo has just started. Therefore, This paper relies on the major project of the national forestry public welfare research projects, which is research and demonstration of key technology for construction of large span bamboo engineering(201204701). This article through to carry out shrinkage and swelling test and long-term creep tests of the recombinant bamboo to establish the dry shrinkage and wet expansion model and creep model, and to apply to the engineering example, is to predict the long-term deformation of bamboo bridge has important practical value.First of all, this article has done the three kinds of dry shrinkage and wet expansion test under different test conditions of recombinant bamboo. The results obtained under the same conditions, the maximum deformation in the thickness direction, the dry shrinkage swelling phenomenon is most obvious, followed by the width direction, and finally the length direction, the results indicated that the recombinant bamboo is a kind of anisotropic materials. At the same time also verified the recombinant bamboo is a kind of porous fiber material, has the obvious shrinkage and swelling properties; And the reference formula considering the shrinkage strain of concrete and the influence of atmospheric humidity and the size parameters of thickness, the linear regression analysis was carried out on the test data, and finally established the dry shrinkage and wet expansion model of recombinant bamboo, to provide theoretical reference for practical engineering applications.Secondly, the long term creep test of recombinant bamboo beams in natural environment was done. Get early creep, creep rate is bigger, rapid deformation, creep rate gradually smaller, after deformation increase slowly, and gradually achieve a stable development of the state; Recombinant bamboo beam surface coating of epoxy resin is less affected by the environment, in the 60 d time, the creep deformation value is 3.06 mm, meeting the requirements of specification; At the same time, this article uses the Burgers model of linear regression analysis of the experimental results to establish creep model of recombinant bamboo, combined with the creep coefficient equation, to establish the creep coefficient equation, and to provide a theoretical reference to predict the long-term deformation of the bamboo bridge engineering.Finally, according to the dry shrinkage and wet expansion model and creep model of recombinant bamboo, long-term performance of recombinant bamboo arch bridge is forecasted. Modeling into bridge 20 years, the total deformation is calculated value of 18.79 mm, to meet the requirements of the specification, to explain the dry shrinkage and wet expansion model and creep model can better predict the long-term deformation of recombinant bamboo arch bridge.