Study On Mechanical Properties Of Oriented Strand Board-Laminated Bamboo Lumber Nail Joints

Modern bamboo and wood structures have many advantages,such as environmental friendliness,high material utilization rate and good seismic performance.The design of the node is related to the safety of the structure.The nail node is widely used because of its safety and reliability,convenient installation and clear force transmission.As new materials,Oriented strand board（OSB）and Laminated bamboo lumber（LBL）have become the research focus of new structural materials in the field of construction.OSB and LBL are organically combined through nails to give full play to the characteristics of these two materials,which is in line with the requirements of comprehensive,coordinated,healthy and sustainable development of the construction industry.It is also a concrete measure to actively practice the development concept of"clear water and green mountains are gold and silver mountains".Based on OSB-LBL single shear node as the research object,monotonous and low reversed cyclic loading experiment was carried out,respectively,to explore the pin diameter,OSB panel side wall distance,LBL bone distance,at the end of the loading direction and loading ways of the nail failure pattern,bearing capacity,deformation,hysteresis property,rigidity degradation and energy dissipation,The finite element software is used for numerical simulation in order to provide basis and reference for the design and application of this kind of nail joints.The main conclusions are summarized as follows:（1）Through the material test of OSB and LBL,the basic mechanical properties of OSB and LBL were determined,and the stable,lightweight and high strength properties of OSB were pointed out,providing theoretical basis for the analysis of the following chapters.（2）Under different loading modes,the nail joints all show the yield mode ofⅢ_ssingle hinge.Under monotonous loading,the main failure modes are bending deformation of nail bar,plate end tearing failure and wall bone splitting failure,and there are a lot of nail fatigue fracture in low cycle repeated loading test.The bearing capacity,stiffness and deformation capacity of monotonic loading specimens are higher than those of low cyclic loading specimens.（3）The nail diameter is an important factor affecting the mechanical properties of the nail joints.Increasing the nail diameter can significantly improve the bearing capacity,initial stiffness,ductility and energy dissipation capacity of the nail joints,and the stiffness degradation is more obvious.The minimum end distance of OSB cladding and LBL wall columns is 15mm.The load-bearing capacity of the longitudinal specimen is slightly higher than that of the transverse specimen.（4）Based on the calculation formula of Chinese Wooden Structure Design Standard,the coefficient k₃in mode 3 is improved,and a modified calculation formula of bearing capacity with relatively small error is proposed.Folz formula can accurately predict the elastic,elastic-plastic and failure stages of OSB-LBL screw joints,which has good applicability.（5）ABAQUS finite element software was used to conduct numerical simulation of OSB-LBL nail joints under monotone load,and the failure modes and load-displacement curves obtained were in good agreement with the test results.