Influence of old panel on the mechanical properties of nailed joints in light wood frame structure
ZHANG Ying;LIU Xinyue;HU Qibin;GAO Ying;MOE Key Laboratory of Wooden Material Science and Application,Beijing Forestry University;
Light wood frame structure consists of wood frame shear wall,floor and roof system. As a main bearing system,the wall can not only withstand vertical loads and transmit the loads to the foundation,but also resist the horizontal effects caused by earthquakes or wind. The shear wall is mainly connected by nails. The performance of nailed joints directly affects the lateral stiffness and horizontal bearing capacity. Current studies focus on the influence of the panel type,thickness and the contact area on the mechanical properties of the nailed joints,in which,all the panels used were newmaterials and no study discussed the effects of old OSB(oriented strand board) on the mechanical property of nailed joints. By comparing the newand old OSB connected to the SPF lumber,this paper aimed at investigating the changing rules of the mechanical performance of nailed joints due to the natural aging OSB panels and then made reference to the design and material selection. The old OSB involved in the research was removed from existed buildings after 6 years' service. Seventy-two nailed joints specimens were made with SPF lumber,the newand old OSB and the domestic twist nails. The nails were driven vertically between the OSB and the SPF lumber according to the directions of perpendicularto-grain and parallel-to-grain. Monotonic loading test was applied based on ASTMD1761-12 to explore the influence of the newand old OSB panels with different thicknesses using the perpendicular-to-grain connection and parallel-to-grain connection on the mechanical properties. Test results showed that,when comparing old and newOSB connections,the load-withstanding,stiffness,and energy dissipation capacity of the nailed joints specimens connected with old OSB had a decreased trend except the ductility factor. The decrease of all mechanical properties for 12.0 mm thick old OSB was smaller than that of the 9.5 mm thick OSB. In the comparison of different thicknesses of OSB,the nailed joints specimens connected with 12.0 mm thick OSB showed better load-withstanding,stiffness,ductility coefficient,energy dissipation capacity than that of the 9.5 mm thick OSB. For the load-withstanding,stiffness,ductility factor,the decrease of perpendicular-to-grain connection of the old OSB was smaller than the parallel-to-grain connection. For the energy dissipation capacity,there was no obvious difference between the parallel-to-grain connection and the perpendicular-to-grain.The fracture modes of nailed joints were typically the OSB and SPF lumber cracking and rods bending,which consisted of the destructive pattern in the European Wood Design Code. The maximum load of the nailed joints can be calculated by the European Wood Design Code. The theoretical calculated values were in good agreement with the experimental values.The maximum load fitting results of the 9.5 mm thick newOSB board connected to the SPF lumber were better than that of the 12.0 mm thick OSB.
【Fund】： 国家重点研发计划(2017YFC0703503);; 国家自然科学基金(31770602);; 北京市支持中央在京高校共建项目(2015-共建)
【CateGory Index】： TU366.2
【CateGory Index】： TU366.2