基于分布式光纤技术的古建木结构变形监测策略

Deformation monitoring strategy for ancient timber buildings based on distributed optic fiber sensing technology

为解决古建木结构在实际监测中因监测内容较多而造成系统臃肿、传感器通道数量过多和数据集成繁琐等问题,提出基于分布式光纤技术的古建木结构梁柱变形监测策略.首先以共轭梁理论和空间几何关系为理论基础,在分析榫卯节点特性和柱脚平摆浮搁式特点基础上推导出结构应变分布信息分别和梁挠度和柱倾角之间的对应关系;其次采用数值仿真和理论分析对所提策略的适用范围和传感器布设进行研究;最后通过单榀木框架静力试验和单柱倾覆试验验证所提监测策略的有效性.研究结果表明:所提出的古建木梁挠度监测技术适用于跨高比20以上的木梁;基于本文布设策略的古建木结构变形监测技术具有较好的测量精度和适用性.

Due to the fact that the huge data should be monitored in the deformation monitoring of ancient timber structures in service, there exits some problems such as system over-stuffed, too large number of sensors channel and too complicated integration of data. To solve such problems, this paper proposed a deformation monitoring strategy based on distributed FBG technology to monitor the deform- ation of ancient timber beam and column. Firstly the deformation mechanism of timber structure is investigates. By analyzing the feature of mortise-tenon and flowing connection between column and base, the relationship is deduced between distributed strain values and the deflection of timber beam and slope angle of timber column based on improved conjugated beam theory and geometrical trigono- metric function relationship. Secondly, the application scope of the proposed monitoring strategy and the sensor layout strategy are discussed through numerical simulation and theory analysis. Finally, the proposed deformation monitoring strategy is validated by a static load test of timber frame and a capsi- zing test of timber column in the laboratory. The results show that the proposed deflection monitoring method is suitable for monitoring ancient timber beam whose span- depth ratio is larger than 20; furthermore, the deformation monitoring technology whereby the proposed sensor deployment strategy applying to ancient timber structures has high precision and good applicability.