Kim Sung Tae, Park YoungHwan, Park Sung Yong, Cho Keunhee, Cho Jeong-Rae
Division of Structural Engineering Research/Korea Institute of Construction and Building Technology, 283, Goyangdae-ro, Ilsanseo-gu, Goyang-si, Gyeonggi-do 411-712, Korea.
Sensors (Basel). 2015 Jan 8;15(1):1060-70. doi: 10.3390/s150101060.
Prestressed Concrete Wire and Strand (PC) strands are the most used materials to introduce prestress in a Pre-Stressed Concrete (PSC) structure. However, it is difficult to evaluate the final prestress force of the PC strand after prestressing or its residual prestress force after completion of the structure on site. This impossibility to assess eventual loss of prestress of the PC strand has resulted in a number of serious accidents and even in the collapse of several structures. This situation stresses the necessity to maintain the prestress force residual or after prestressing for the evaluation of the health of the concrete structure throughout its lifespan. Recently, several researchers have studied methods enabling one to verify the prestress force by inserting an optical fiber sensor inside the strand but failed to provide simple techniques for the fabrication of these devices to fulfill measurement performance from the design prestress to failure. Moreover, these methods require the additional installation of electrical resistance strain gages, displacement sensors and load cells on the outer surface of the structure for long-term precise measurement. This paper proposes a method enabling one to evaluate precisely and effectively the prestress force of the PC strand and intends to verify the applicability of the proposed method on actual concrete structures. To that end, an innovative PC strand is developed by embedding a Fiber Bragg Grating (FBG) sensor in the core wire of the PC strand so as to enable short term as well as long term monitoring. The measurement performance of the developed strand is then evaluated experimentally and the reliability of the monitoring data is assessed.
预应力混凝土钢丝和钢绞线（PC）是在预应力混凝土（PSC）结构中引入预应力最常用的材料。然而，在现场对预应力后的PC钢绞线的最终预应力或结构完成后的残余预应力进行评估是困难的。无法评估PC钢绞线最终的预应力损失已导致多起严重事故，甚至造成一些结构的倒塌。这种情况凸显了在混凝土结构的整个使用寿命期间，保持预应力残余或预应力后对评估结构健康状况的必要性。最近，一些研究人员研究了通过在钢绞线内部插入光纤传感器来验证预应力的方法，但未能提供制造这些装置的简单技术，以实现从设计预应力到破坏的测量性能。此外，这些方法需要在结构外表面额外安装电阻应变片、位移传感器和称重传感器，以进行长期精确测量。本文提出了一种能够精确有效评估PC钢绞线预应力的方法，并打算验证该方法在实际混凝土结构上的适用性。为此，通过在PC钢绞线的芯线中嵌入光纤布拉格光栅（FBG）传感器，开发了一种创新的PC钢绞线，以便进行短期和长期监测。然后对开发的钢绞线的测量性能进行实验评估，并评估监测数据的可靠性。
