Shin Kyung-Joon, Lee Seong-Cheol, Kim Yun Yong, Kim Jae-Min, Park Seunghee, Lee Hwanwoo
Department of Civil Engineering, Chungnam National University, Daejeon 34134, Korea.
Department of NPP Engineering, KEPCO International Nuclear Graduate School, Ulsan 45014, Korea.
Sensors (Basel). 2017 Aug 10;17(8):1843. doi: 10.3390/s17081843.
The potential for monitoring the construction of post-tensioned concrete beams and detecting damage to the beams under loading conditions was investigated through an experimental program. First, embedded sensors were investigated that could measure pre-stress from the fabrication process to a failure condition. Four types of sensors were installed on a steel frame, and the applicability and the accuracy of these sensors were tested while pre-stress was applied to a tendon in the steel frame. As a result, a tri-sensor loading plate and a Fiber Bragg Grating (FBG) sensor were selected as possible candidates. With those sensors, two pre-stressed concrete flexural beams were fabricated and tested. The pre-stress of the tendons was monitored during the construction and loading processes. Through the test, it was proven that the variation in thepre-stress had been successfully monitored throughout the construction process. The losses of pre-stress that occurred during a jacking and storage process, even those which occurred inside the concrete, were measured successfully. The results of the loading test showed that tendon stress and strain within the pure span significantly increased, while the stress in areas near the anchors was almost constant. These results prove that FBG sensors installed in a middle section can be used to monitor the strain within, and the damage to pre-stressed concrete beams.
通过一个试验项目，研究了监测后张法预应力混凝土梁的施工过程以及检测梁在加载条件下损伤情况的可能性。首先，对能够测量从制造过程到破坏状态的预应力的嵌入式传感器进行了研究。在一个钢框架上安装了四种类型的传感器，并在对钢框架中的预应力筋施加预应力时，测试了这些传感器的适用性和准确性。结果，选择了一种三传感器加载板和一个光纤布拉格光栅（FBG）传感器作为可能的候选方案。使用这些传感器，制作并测试了两根预应力混凝土受弯梁。在施工和加载过程中对预应力筋的预应力进行了监测。通过试验证明，在整个施工过程中成功监测到了预应力的变化。成功测量了在张拉和储存过程中发生的预应力损失，甚至包括混凝土内部发生的损失。加载试验结果表明，纯跨内的预应力筋应力和应变显著增加，而锚固区附近的应力几乎保持不变。这些结果证明，安装在中间截面的FBG传感器可用于监测预应力混凝土梁内部的应变以及损伤情况。
