Study On Dowel-Bearing Properties Of Cross-Laminated-Timber (CLT) Panels Of Canadian Hemlock

Cross laminated timber(CLT)is a new type of green building material,which can be prefabricated,lightweight and high-strength,and orthotropic,so it has set off a wave of CLT construction worldwide,especially in Europe and North America.At present,CLT mainly plays the role of shear wall and floor in the building structure,and China's research on the connection of CLT nodes is still in its infancy.Based on this,this paper conducts experimental research on the dowel-bearing strength capability of CLT components under various working conditions,and provides a reFerence for the subsequent research of CLT mechanical parameters.The main work of this article is as follows:(1)This paper compares and analyzes the design codes and regulations of wood structures in various countries,summarizes relevant literature at home and abroad,comprehensively considers the differences between the two test methods of ASTM(D5764-97a)and EN383-2007,and finally puts forward the test plan of this article;(2)Based on the consideration of the influence of 4 kinds of dowels diameters,5 kinds of position relationships between seams and dowels,2 kinds of loading angles,and 2 kinds of dowel positions variables,a total of 128 CLT members in 64 groups were designed for static loading test research,and 64 groups of members were obtained.Vertical load-displacement curves,deformation modes,dowel-bearing strength values and influencing factors;(3)When comparing the "Canadian Standard Association International"(CSA O86-14),"Orthogonal Glulam(CLT)Structure Technical Guide" and the US CLT handbook,we can find that the calculation methods of dowel-bearing strength in the above specifications is applied Sometimes has certain limitations.This paper combines the test model to integrate and modify the calculation method of the dowel-bearing strength in the above specifications,and puts forward the recommended formula applicable to various working conditions.In addition,the test values are compared with related literatures.When Uibel and Blab formulas are used in the case where the dowels are arranged perpendicular to the surface plane,it is recommended to reduce the predicted results of the formula.It is suggested that the reduction factor should be considered as 0.65 and 0.6 when the loading angle is 0° and 90°;(4)This paper uses ABAQUS finite element analysis software to establish 5 finite element models,and the following conclusions are obtained through finite element analysis: First,the maximum stress of the specimens is always distributed at the bottom of the dowel groove;Secondly,the stress is transmitted in the vertical direction when bearing along the grain,and the stress is transmitted in the transverse direction when the transverse grain is under pressure.Stress has always been development along the wood grain direction;Finally,because the center laminate of the specimen is constrained by the adjacent laminate,its strength capability and deformability are improved.