Study On Deformation Monitoring And Damage Detection Of Joints In Ancient Timber Buildings

Chinese ancient wooden structures take an important role in the world due to its ornate interior and reasonable layout. Meanwhile, they are important cultural relics and precious historical heritage and enjoying a high reputation in the world. However, because wooden is easily to be decayed and moth-eaten and the wooden structures are suffered to adverse environmental factors and the effects of fatigue loads, corrosion effects in the course of their service. Some inevitably damages were emerged. For examples, structural deformation, damage accumulation and decay resistance. They are seriously affecting the safe use of the ancient wooden buildings. Therefore, the author focuses on a series of researches about deformation monitoring and damage detection in ancient wooden buildings, the following conclusions can be made:(1) In view of three main failure modes for traditional ancient wooden building, namely oversize deflection of beam, damage of mortise-tenon joints and sloping of pillars, the thesis firstly starts to investigate the failure reasons, commonly used damage detection techniques and long-term structural monitoring techniques. Three deformation monitoring techniques involving FBGS-based deflection monitoring, displacement meter-based mortise-tenon joints monitoring and inclinometer-based sloping of pillars monitoring are proposed. Finally, the above deformation monitoring techniques are validated by a wooden frame structure subjected to static and quasi-static loads. The results show that the proposed methods have high precision and feasibility.(2) For the purpose of detecting the stiffness of mortise-tenon joints for wooden structures, the damage joint index based on the upper and lower limit points from quality control chart is proposed, and thus the stiffness identification method is also presented. A wooden frame structure in laboratory is conducted to validate the proposed method. The results indicate that this indicator is correlated with secant stiffness of mortise-tenon joint. In particular, with the development of damage, the secant stiffness of mortise-tenon joint declines, while the index rises. The damage evolution and quantization can accordingly be evaluated for mortise-tenon joint.(3)Based on the requirement of deformation monitoring in the wooden structure, a deformation monitoring system is developed by using VB software. The system involves three components:sensor module, signal acquisition module, and data analysis and processing module. The deformation monitoring system validated by a wood frame test in laboratory is capability of quick and efficient long-term deformation monitoring for wooden structures...