Study Of Short-Term Flexural Behavior For Glue-Bamboo And Lumber Beam Under Different Pre-stressed State

Because of a series of advantages, such as energy-saving, environmental protection, safe and livable and so on, the bamboo and lumber buildings were preferred by more and more people. Thus, for pre-stressed glue-bamboo and lumber beams, as one of the main stress components, it was necessary to research it. However, for ordinary glue-bamboo and lumber beams, it had many problems like bigger deformation, easy to brittle tensile failure and could not fully use materials strength and so on. Therefore, the pre-stressed glue-bamboo and lumber beam, whose most tensile stress was bore by pre-stressing tendons was proposed. At present, the domestic and overseas research mainly focused on the material behavior of composite bamboo and lumber, the mechanical behavior and failure mode research of glue-bamboo beams and glue-lumber beams, the research of pre-stressed lumber beams, and there were no research on pre-stressed glue-bamboo and lumber beams. Based on above situation, the following works were conducted in this paper:First, a new end anchorage device was proposed. This device consist of hollow steel tank, wedge-shaped steel plate and anchorages. By this device, the pre-stressing tendons and glue-bamboo and lumber was worked separately, which let the effective distance between them was ensured, to let the whole cross section compression as far as possible to achieve, and meanwhile, the stress concentration caused by slot was avoided.Second, through the two three-divide points stretch in beam bottom surface, the bending experiment was conducted in 12 groups pre-stressed glue-bamboo and lumber beams and 4 groups ordinary glue-bamboo and lumber beams. From the angle of ultimate bearing capacity, failure mode, load-deflection relation curve and load-stress relation curve, the influence of pre-stressing tendons number and pre-stressed value on glue-bamboo and lumber beam was researched. The results showed that:Under same pre-stressed value, with the increase of pre-stressing tendons number, the glue-bamboo and lumber beam bending stiffness and ultimate bearing capacity was increased; Under same pre-stressing tendons number, with the increase of pre-stressed value, the glue-bamboo and lumber beam ultimate bearing capacity was increased, while the bending stiffness basically stayed unchanged; Compared with ordinary glue-bamboo and lumber beam, under same bearing capacity, the pre-stress could save material about 13.28%～51.98%, and reduce the cost aboutl.95%～39.61%.At last, with ABAQUS finite element analysis, the glue-bamboo and lumber beam finite element mode was built. In this part, the influence of pre-stressing tendons number and pre-stressed value on glue-bamboo and lumber beam bending behavior was researched, and compared it with actual experiment results, to analysis the difference between simulation results and actual experiment results and its reason.