光纤光栅在预应力钢绞线应力监测中的应用

Application of fiber bragg grating sensor to monitor tensile stress in a seven-wire prestressed steel strand

钢绞线是预应力混凝土结构中应用最广泛的预应力筋,服役期间处于高应力应变状态,易受应力腐蚀,存在安全隐患,因此,对其应力状态进行监测具有重大意义.研究裸光栅和FRP筋封装光纤光栅的应变传感性能和温敏特性,在此基础上进行光纤光栅监测钢绞线应力的试验研究,并研制了光纤光栅智能钢绞线.结果表明:采用光纤光栅监测预应力钢绞线应力是可行的,由于裸光纤光栅比较脆弱且传感量程较小,只适用于张拉后的预应力筋,FRP筋封装光纤光栅可用于大应力应变预应力筋的监测.

A seven -wire steel strand is widely used as prestressed reinforcement in prestressed concrete structures. As a high stress component, it suffers from stress corrosion easily. So it is significant to monitor its in - service stress. First, the stress and temperature sensor characteristics of the nude Optical Fiber Bragg Grating （OFBG） sensors and FRP - OFBG sensor bars were studied in this paper. Subsequently the technology of applying Fiber Bragg Grating sensor to monitor tensile stress in a prestressed steel strand was studied and a smart seven -wire steel strand was obtained. The results show that it is feasible to use OFBG sensor technology measuring strand stress. The nude OFBG sensor is brittle and has small sensor range, so it is suitable for pretension strand. FRP -OFBG sensor bars can be used for large strain strand.