Stress Monitoring on GFRP Anchors Based on Fiber Bragg Grating Sensors.

Xiao-Long Zhou,Yuan Zhou,Hai-Lei Kou,Wang Li,Wang-Chun Zhang

doi:10.3390/s19071507

Abstract

Glass fiber-reinforced polymer (GFRP) bolts have been widely used in some applications of grouted anchors because of the advantages of better resistance to corrosion, high strength-to-weight ratio, low electromagnetic properties, and so on. This study presents a field test to assess the feasibility of fiber Bragg grating (FBG) sensors in monitoring the stress profile of GFRP anchors during pulling test. Two GFRP anchors were fully instrumented with FBG sensors and then installed into the ground using a drilling and grouting method. To measure the stress profile along test anchors, seven bare FBG sensors were arranged in a single optical fiber and then embedded in the middle of GFRP bolts in the process of extrusion molding. The procedure for embedding bare FBG sensors into GFRP bolts is introduced first. Then, the axial forces and shear stresses that were calculated from the measurements of the FBG sensors are discussed. The field test results indicate that the embedded FBG technology was feasible to monitor the stress state of GFRP anchors during pulling.

Highlights

Glass fiber-reinforced polymer (GFRP) materials have been increasingly used in civil engineering in the past few decades [1], such as GFRP rebars in concrete beams, strengthening of concrete girders with epoxy-bonded GFRP plates, GFRP connections, fire protection of GFRP pultruded profiles, and so on [2,3,4,5]
The pulling out tests were conducted 28 days after GFRP anchor installation
In order to avoid of GFRP anchor during pulling, a steel bar with 32.0 mm inner diameter, 10.0 mm wall thickness, the crushing failure of GFRP anchor during pulling, a steel bar with 32.0 mm inner diameter, and 1.0 m length was used to reinforce the exposed portion of the anchors and connect the anchors

Summary

Introduction

Glass fiber-reinforced polymer (GFRP) materials have been increasingly used in civil engineering in the past few decades [1], such as GFRP rebars in concrete beams, strengthening of concrete girders with epoxy-bonded GFRP plates, GFRP connections, fire protection of GFRP pultruded profiles, and so on [2,3,4,5]. GFRP materials have the advantages of better resistance to corrosion, high strength-to-weight ratio, and low electromagnetic properties, and GFRP bolts have been an alternative to steel in some applications of grouted anchor bolts [6]. In this system, antipulling tests are vital for understanding the actual field behavior of anchors for determining the relevant geotechnical parameters [7,8]. Appropriate instrumentation is crucial for GFRP anchors so that useful and reliable parameter values are obtained for the designers [9,10] Traditional sensors, such as electrical resistance strain

Methods

Results

Conclusion