准分布式FBG钢绞线传感性能分析与RPC梁变形监测试验研究

Sensing-Performance Analysis of Quasi-Distributed FBG Steel Strands and Experimental Study on Deformation Monitoring of RPC Beams

针对预应力混凝土结构预应力筋受力状态的监测难题,提出了凹槽预压封装准分布式FBG技术,解决了FBG存活率低和监测量程不够的技术难题。通过循环张拉试验和预应力RPC梁加载试验,探究了准分布式FBG钢绞线的传感性能及其对混凝土结构应力状态的监测效果。结果表明,FBG存活率为100%,应变灵敏度为0.00118~0.00120 nm/με,应变传递率β≥0.98,线性度≤2.096%,回差≤1.043%,重复性≤3.615%,总不确定度≤3.881%。准分布式FBG钢绞线可准确识别RPC梁的损伤过程,45%f_(ptk)、65%f_(ptk)、75%f_(ptk)(f_(ptk)为钢绞线极限强度)预应力RPC梁的开裂荷载分别为100 kN、130 kN、140 kN,纵筋屈服荷载分别为260 kN、280 kN、300 kN。RPC梁挠度和钢绞线应变为抛物线型分布,最大挠度分别为27.691 mm、20.153 mm、14.602 mm,最大应变分别为4163.025με、3715.126με、1658.487με。准分布式FBG为预应力结构的整体监测提供了思路。

To address the monitoring of the stress state of prestressed steel strands in prestressed concrete structures,a groove preloading encapsulation quasi-distributed FBG technology is proposed to solve the low survival rate and insufficient monitoring range of FBG.The sensing performance of quasi-distributed FBG steel strands and their monitoring effect on the stress state of concrete structures are investigated via cyclic tension and prestressed RPC-beam loading tests.The results show that the survival rate of the FBG is 100%,the strain sensitivity is 0.00118-0.00120 nm/με,the strain transfer rateβ≥0.98,the linearity≤2.096%,the hysteresis≤1.043%,the repeatability≤3.615%,and the total uncertainty≤3.881%.The quasi-distributed FBG steel strand accurately identifies the damage process of the RPC beams.The cracking loads of 45%f_(ptk),65%f_(ptk),and 75%f_(ptk) prestressed RPC beams are 100,130,and 140 kN,respectively,and the yield loads of the corresponding longitudinal bars are 260,280,and 300 kN,respectively.The deflection of RPC beams and the strain of steel strands indicate a parabolic distribution,with maximum deflections of 27.691,20.153,and 14.602 mm,respectively,and maximum strains of 4163.025με,3715.126με,and 1658.487με,respectively.The quasi-distributed FBG provides ideas for the overall monitoring of prestressed structures.