Investigation On Flexural Behaviour And Design Of C-shaped Joists Utilizing Small-diameter Timber

As a kind of light weight and high strength green building materials,wood has good seismic performance,beautiful appearance,good processing performance,fast construction and renewable resources.Wood structure has always played an important role in human construction activities,modern wood structure buildings are comfortable and liveable with good thermal insulation performance,of which light wood structure buildings account for about 70%,widely used in foreign countries,since the introduction of China around 2000 has also made certain applications in China.Light wood structure is composed of shear walls and cross partitions(roof,floor cover)of panel wall structure,shear walls and cross partitions to the dense specification of wood studs or shelves as the framework,laying nail wood-based structural panels and other surface materials and become,where the specifications used and wood-based structural panels are standardized,factory-made products.The light wood structure is introduced into China by North America,and most of the materials used are imported and the cost is high,so it is mainly for the high-end residential market,and it is difficult to promote a large number of applications.In this paper,a new type of small diameter wood C-shaped composite joist is proposed based on the small diameter wood joist proposed in the previous study,and a new type of small diameter wood C-shaped composite joist is proposed and studied by experimental research,numerical simulation and design method by improving the cross-sectional structure and the form of flange joint.The load-displacement curves and damage patterns of each joist were obtained through the tests.Based on the above-mentioned tests,a series of material and joint performance tests were conducted to accurately grasp the material and joint mechanical properties of the joists.The accuracy of the numerical model was verified by comparing with the test results.Based on the numerical model,the deformation state and failure mode of the members,especially the weak points in the joint area,were investigated,and the influence of the web and flange material strength on the load carrying capacity was investigated by parametric analysis.A complete design method for small-diameter timber composite joists,including load capacity and deformation analysis,is proposed,drawing on the analysis method for mechanically connected composite sections in EC5.The research results achieve a more reasonable solution and design method of small diameter timber joist,which can replace the specification timber joist in the transverse partition of light wood structure,and make reasonable use of the domestic natural resources of small diameter timber and reduce the construction cost,which is beneficial to the promotion and application of light wood structure.