An Experimental Study On Glue Laminated Bamboo I-joists

Promoting the application of glued bamboo structure in our country,not only can realize low-carbon environment,but also provide green circular economy industrial chain and improve farmers' income,in addition improve the seismic performance of the building,finally realize the diversification of building materials.As the horizontal bearing member commonly used in the bamboo structure,the bamboo I-joists' bearing capacity and deformation performance are directly related to the safety performance of the whole structure.Therefore,it is of great value in the research of bamboo structure.Through experimental research,this paper is to provide a reference for the design and application of glued bamboo I-joist in our country.First of all,the article briefly introduced the GluBam and GluBam I-joist.The measured water content of the GluBam was determined by the experiment,and the measured water content of the material could met the requirements of the specification.The GluBam I-joists with different spans and cross-section dimensions were tested by loading at the three-point points of the net span.The failure modes,load-deflection curves,ultimate loads,and cross-section normal strain and strain of the cross-section of webs were obtained by experiments.Secondly,the bending stiffness and shear stiffness of the GluBam I-joists were obtained through the intersection of the flexibility functions of specimens with the same cross-section.The bending stiffness could meet the requirements of the specification and then compare with the theoretical section stiffness.The results showed that the stiffness of the specimens with discontinuous connection between the flange and the web was lower than that of the specimen with continuous connection between the flange and the web.When I-joists serve as a floor joist,the deformation can be comparable with wood I-joists.The the maximum spans of GluBam I-joists are 7m to 11m,with a strong engineering and practical value.At the same time,the strain at different heights of the cross section and the main strain of the shear web were analyzed.The strain of the cross section in the cross section of the GluBam I-joist is linearly distributed along the height,and the failure modes were further analyzed.According to the failure modes and cross-section strain changes of each group,the bearing capacity of the GluBam I-joists is mainly controlled by the shear strength and the bending strength.In the fourth chapter,based on the experimental results,the shear strength and the bending strength of the cross section were analyzed.Also,the main mechanical properties of the GluBam I-joists were given as the engineering design reference.The GluBam I-joists meeting the deformation requirements can hold the design floor load.The specimen with large span-depth ratio and less lateral support lost the overall stability during the loading process.The last chapter briefly introduced the research and specification of lateral stability of bamboo or wood beams and I-joists.At the same time,the lateral stability of the GluBam I-joists was studied by combining the experimental results and the related theories.