光纤法珀应变测量系统在混凝土弹性模量标定中的应用

基于光纤法珀应变传感器的基本原理,介绍了一种混凝土弹性模量标定的新方法。描述了利用光纤法珀应变传感器进行的混凝土弹性模量标定实验,给出了混凝土的标定曲线,并计算出了混凝土试验块的弹性模量。     

光纤法珀传感器及其在桥梁应变监测中的应用

应变是反映桥梁健康状况的重要参数，将光纤法珀传感器埋入混凝土结构内部，作为桥梁应变的智能传感元件，它与光开关、光纤应变解调仪、计算机等组成应变测量系统，可以实现桥梁应变自动监测。目前，该系统已经安装在重庆大佛寺长江大桥上，监测数据表明光纤法珀传感器的稳定性和可靠性好，能够用于大桥应变的长期监测。     

混凝土固化期收缩应变监测的光纤珐珀传感器

针对混凝土固化监测的难题,提出了采用光纤珐珀传感器进行混凝土固化过程中收缩应变监测的新方案,分析了光纤珐珀传感器的传感原理,研制出了相应的实验系统,对440mm×50mm×40mm的混凝土试件进行了实验,在试件两天的固化过程中监测到了130με的收缩应变.本文还对光纤珐珀应变传感器的温度稳定性能进行了理论分析及对比实验,实验结果表明,在一定条件下环境温度对光纤珐珀应变传感器的影响可忽略不计.     

基于FBG传感器的桥梁结构应变监测

文章通过在桥梁模型中埋入光纤布拉格光栅传感器,验证FBG传感器可应用于桥梁结构的应变监测。首先介绍了光纤传感技术、国内外的发展现状及应用,比较了目前较为常用的两种光纤传感器:光纤光栅传感器、光纤法珀传感器。接着着重介绍了本次试验所用的FBG传感器,然后通过对桥梁模型的结构分析确定监测内容,并进行应力分布研究,在此基础上完成对FBG传感器的优化布设。最后,通过对数据的采集和评估验证监测系统可行性。应用结果表明,FBG传感器系统可以很好地反映桥梁结构应力变化,能够实现对桥梁结构健康监测。     

几种常用应变测试技术的比较分析

重点介绍了电阻应变片、差动式应变传感器及光纤（F-P）应变传感器的工作原理，并结合工程实例对电阻应变测试技术及光纤应变测试技术进行了分析研究。     

基于光纤光栅传感技术的桥梁结构应变监测可行性研究

该文阐述了光纤光栅传感技术的基本原理及其优势,介绍了光纤Bragg光栅传感器(FBG)的布设工艺。利用埋入武黄高速公路某大桥内的FBG和电阻应变片实现了该桥梁在荷载试验过程中的应变监测。并通过比较FBG与电阻应变片测得的应变值来验证光纤Bragg光栅(FBG)传感技术用于桥梁应变监测的可行性。     

光纤光栅应变传感器二维应变测量方法

文章介绍了光纤光栅二维应力传感测量的试验台的准备、光纤光栅的制备、光纤光栅的粘贴、实验仪器、实验过程、光纤光栅测量应变与电阻应变片的测量结果作对比。实验结果说明利用光纤光栅应变花可以得出与电阻应变花一致的结果。     

基于光纤光栅传感技术的超高层建筑结构监测

为验证光纤光栅传感器测量的准确性和精度,将光纤光栅传感器布设于钢筋混凝土梁构件中,用于监测其受力应变值,试验所得到的应变监测结果与电阻应变片结果、理论计算值结果相吻合。然后将光纤光栅传感器成功地应用到超高层建筑的重要构件应力监测中,探索了适合土木工程现场施工特点的光纤传感器埋设工艺和传感系统保护方法,监测了构件在施工过程中的应力变化。工程应用表明:光纤布拉格光栅是实现结构长期健康监测的可靠手段。     

光纤光栅传感器监测混凝土固化收缩实验研究

介绍了光纤光栅应变传感器的基本原理及优点,开发了基于光纤光栅技术的温度传感器与应变传感器,并对它们的工作特性进行了分析;应用裸光纤光栅和自制封装的光纤光栅传感器,监测了混凝土梁固化过程(2~16 h)中混凝土内部的温度变化,以及混凝土内部和钢筋表面的收缩应变.实验结果表明:在使用光纤光栅对混凝土固化期收缩应变监测时必须考虑温度的影响,要进行温度补偿,该监测方法是混凝土养护期恶劣环境条件下收缩应变监测的理想方法,可用于任意尺寸的大体积混凝土固化期温度应变的监测.     

基于白光干涉原理的光纤传感技术——V.光纤传感器和基体材料的相互作用

建立并测试了一个简单的模型,利用该模型可将光纤传感器测得的数值来解释结构的实际应变。光纤传感器测得的应变并不能完全表征试件或结构的应变,因此由理论分析所得的结果非常重要。所采用的光纤及其保护涂敷层的机械特性可改变传感器的应变传递能力。很多前提假设可通过系统的表达式对数学的严格性进行简化,光纤的应变传递特性取决于与承受应变的材料相接触的玻璃纤芯、保护涂敷层和光纤传感长度。数学公式导出了同样数量级的应变。有效长度长的传感器中的界面切应变效应弱于有效长度较短的传感器,理论结果可通过包括白光干涉仪在内的一系列实验进行验证。由此研究得到的最重要的结果就是提出了描述α(L,k)的理论表达式,α(L,k)为可用光纤感知到的应变(珋εg)确定实际引入到材料中的应变(εm)的比例系数。这一关系使得在将光纤传感器应用到结构传感应用之前不必对应变数据进行标定和回归分析,通过反复实验,验证了理论分析的有效性。由此可知,对于带有涂敷层的光纤,可在应变仪与光纤传感器测得数值之间得到一一对应的关系。对于裸纤可得α=1.0,这种情况下无需利用本研究所得的结果。然而,裸纤非常脆弱因此很难应用到实际测量中。     

Quantitative assessment of temperature effect on cone resistance

The measurements of a strain gauge type cone penetrometer are influenced by the temperature change during penetration. A real-time temperature compensation technique using a fiber Bragg grating (FBG) sensor is suggested to correct the effect of temperature on cone tip resistance. A 7-mm micro cone penetrometer equipped with FBG sensors and electrical strain gauges was developed to evaluate the suggested technique. Design concepts include the cone configuration, sensor installation and the temperature compensation process. It is shown that the measured cone tip resistance is significantly affected by the temperature; the error increasing with increasing temperature change. The cone tip resistance measured by the FBG sensor is effectively corrected by the real-time compensation method. The q _c profile of the strain gauge indirectly corrected by the re-penetration test is quite similar to the real-time compensated profile. It is concluded that the proposed real-time temperature compensation using the FBG sensor is an effective technique to obtain reliable cone tip resistance profiles.     

A method for correcting field strain measurements to account for temperature effects

Measurements of deformation and strain are of critical importance for the structural health monitoring of geosynthetic reinforced soil (GRS) structures. For some commonly used wiring configurations and sensors, field strain measurements can exhibit apparent strains that are caused by changes in wire temperature or changes in gauge temperature, which do not correspond to changes in actual strain in the geosynthetic. Correcting for these effects is important for separating out real structural behavior from wiring and sensor issues, and is imperative for avoiding false trigger warnings in automated instrumentation reporting systems. The current paper consequently presents a method for correcting field strain measurements to account for temperature effects. Data collected from sensors embedded in a heavily-instrumented GRS abutment over a two-year monitoring period is presented. The distributed thermistor array embedded in the GRS abutment is shown to be particularly useful for understanding temperature effects on the measured foil strain gauge data. The presented approach and associated framework for data correction are useful for practicing engineers and other researchers, as the general concepts from this study can be applied to data collected from many instrumented geosynthetic field projects.     

土木工程施工过程的光纤光栅监控技术

光纤光栅传感器性能优良,适合土木工程应变的长期测量。对光纤光栅传感器用于土木工程监测的布设工艺等相关问题进行了研究,并在江苏省邮政通信指挥中心工程成功地使用光纤光栅传感器对施工中结构受力体系转换过程进行了监控。结果表明,光纤光栅传感器测量数据稳定可靠,并且能进行分布式测量,效果明显优于传统的应变计。     

光纤Bragg光栅传感器在钢筋混凝土梁静荷载试验中的研究

光纤Bragg光栅的发展使传感器自标定 ,不受光波的波动影响 ,且于光源和连接损耗无关 ,而这些因素却一直困扰着其他类型的光纤传感器。将光纤Bragg光栅和传统电阻应变片分别贴于H15 4和H15 5梁的混凝土表面 ,以及H15 6和H15 8梁的钢筋表面 ,以分别检测钢筋的拉应变和混凝土的压应变。当钢筋混凝土梁受到千斤顶的加载时 ,其应变可由上述传感器检测得到。光纤Bragg光栅传感器的波长偏移提供了一种绝对测量 ,可避免对建筑结构的不间断检测 ,而代之以需要之时的周期性检测     

双压力传感器埋入式沉降仪的研制及应用

针对传统沉降板在高速公路软基沉降观测中存在干扰施工、操作繁琐等弊端,提出了一种双压力传感器埋入式沉降仪。该沉降仪基于将土体沉降测量转换为对密闭系统内液体压力变化测量的原理,主要由竖向密闭管、基准传感器和路基传感器构成。通过室内试验和现场试验,详细阐述了其在标定、埋设和数据采集等阶段的操作方法。研究结果表明,该沉降仪的测量精度可达2 mm,重复性误差2 mm。与传统沉降板方法相比,其主要优势有:(1)该沉降仪埋设在土体中,与地面施工互不干扰;(2)只需分别采集双压力传感器的读数,测量效率高;(3)可用于工后沉降的长期观测,测量成本低。     

应变传感器稳定性研究

应变传感器稳定性一直是国内传感器行业及工程检测行业关注的问题,应变传感器指标很多,且指标之间不存在简单数学关系,所以传感器长期稳定性不能笼统的研究。本文给出了应变传感器工作原理,从材料力学,量子力学和电子力学方面深入探讨了造成应变传感器不稳定性的本质原因,并总结了改善应变片不稳定性常用的方法。本文的论述对应变传感器设计及工程应用具有一定的参考价值     

Toward an Integrated Smart Sensing System and Data Interpretation Techniques for Pavement Fatigue Monitoring

Abstract: Currently, pavement instrumentation for condition monitoring is done on a localized and short‐term basis. Existing technology does not allow for continuous long‐term monitoring and network level deployment. Long‐term monitoring of mechanical loading for pavement structures could reduce maintenance costs, improve longevity, and enhance safety. In this article, on‐going research to develop and validate a smart pavement monitoring system is described. The system mainly consists of a novel self‐powered wireless sensor based on the integration of piezoelectric transduction with floating‐gate injection capable of detecting, storing, and transmitting strain history for long‐term monitoring and a novel passive temperature gauge. A technique for estimating full‐field strain distributions using measured data from a limited number of implemented sensors is also described. The ultimate purpose is to incorporate the traffic wander effect in the fatigue prediction algorithms. Preliminary results are shown and limitations are discussed.     

Numerical investigation and optimal design of fiber Bragg grating based wind pressure sensor

A wind pressure sensor based on fiber Bragg grating (FBG) for engineering structure was investigated in this paper. We established a transaction model of wind pressure to strain and proposed a method of temperature compensation. By finite element analysis, the basic parameters of the sensor were optimized with the aim of maximum strain under the basic wind pressure proposed in relative design code in China taking geometrical non-linearity into consideration. The result shows that the wind pressure sensor we proposed is well performed and have good sensing properties, which means it is a technically feasible solution.