Research And Analysis Of Timber Beams’ Appropriate Strengthening Methods

Ancient timber structures are the important cultural heritage in our country, which need to be carefully protected. After hundreds of years, timberwork often exist all kinds of damage, such as decay, termite damage, and so on. In order to retain historical information as much as possible, remove badly damaged parts in timber components and replaced with new members is better than replace all the components. Traditional splicing methods of timber beam use the combination of screw and steel plate. Those methods are easy to implement and widely used in the ancient timberwork. But traditional patchwork method will produce certain damage to the original components, which is inconsistent with the purpose of the protection of cultural relics. To meet the needs of architectural heritage protection, the rectangular steel tube splicing method is proposed. The study of this method will provide references to ancient wooden beam protection works.In order to study the bending behavior of timber stitching beam spliced with rectangular steel tube,15 wood beam components with different spliced joint parameters (including 3 undamaged beams) are designed four point bending loading tests. The size of those beams is 150mm × 200mm × 2300mm.15 beams are divided into four groups (undamaged beams group, tenon length changing group, extra steel pipe length changing group, injected glue group), to study the effects of different parameters on the bending behavior of timber beams. Experimental results show that under the same test condition, as the extra steel pipe length increasing, the failure models of splicing timber beams change from tenon’s dropping off to tenon’s broken; The tenon length changing has little impact on failure model; The bending bearing capacity of splicing timber beams are less than undamaged timber beams (less than 48%); As the tenon length and extra steel pipe length increasing the bending bearing capacity and stiffness of splicing timber beams are improved; Injecting glue into splice joint can significantly improve the bending bearing capacity and stiffness of splicing timber beams. But injecting operation is irreversible, the wood property of the splice joint area is changed and become very brittle.By means of finite element software ABAQUS, splicing timber beams’finite element model are established. By comparing the results of bending loading tests and numerical simulation, the feasibility and reliability of numerical simulation analysing is proved. On this basis, using the average timber material properties to analysis the effects of different parameters on the bending behavior of timber beams. Then the calculation formula of the flexural bearing capacity of timber Stitching beam spliced with rectangular steel tube can be derived. Comparing the results of formula calculation with numerical simulation, validity of the simplified calculation method is proved.