基于磁弹效应的预应力钢绞线全量应力监测实验研究

Elasto-magnetic Effect Based Total Stress Monitoring of Prestressed Steel Strands: Experimental Investigation

预应力钢绞线是预应力结构的关键承力部件,其应力状态直接影响预应力结构的承载能力。对钢绞线进行全量应力监测是评价预应力结构安全状况的有效手段。本文分析了预应力钢绞线全量应力监测的特殊性,讨论了基于磁弹效应的应力监测方法的优势,介绍了其工作原理及系统组成。建立了进行钢绞线全量应力监测研究的实验装置,开发了一套基于Lab VIEW平台的测试系统,并对标号15-7Φ5的钢绞线进行了应力监测实验。内容包括单根钢绞线的传感器标定、被测钢绞线周围加其他钢绞线的传感器标定以及用前者标定公式进行后者应力测量的有效性验证。实验证明所研发的基于磁弹效应的应力监测系统测量精度高、可重复性好和抗磁干扰能力强,适合预应力钢绞线的全量应力监测。

The prestressed steel strands are the critical bearing components of prestressed structures.The stress state of the former directly affects the loading capacity of the latter.The total stess monitoring of prestressed steel strands is one of the effective measures to assess the safety of prestressed structures.This paper analyzed the particularity of the stress monitoring of prestressed steel strands,and discussed the superiorities of the elasto-magnetic （EM）effect based method.The working principle and system structure of the EMeffect based stress monitoring system were introduced.An experimental setup for stress monitoring of prestressed streel strands was built,and a testing system based on LabVIEW platform was developed.The experiments were conducted on the steel strand signed 15-7Φ5.The calibration experiments for a single strand,and for a strand embraced by other strands were carried out.The feasibility of force measurement in the latter case by the former calibration formula was verified.Conclusions were drawn from those experimental results that the developed stress monitoring system has high accuracy,good repeatability and high capability of anti-magnetic-interference.It is thus feasible for total stress monitoring of prestressed steel strands in prestressed structures.