Pullout Behavior of GFRP Anti-Floating Anchor Based on the FBG Sensor Technology

Ming-Yi Zhang,Xiao-Yu Chen,Zheng Kuang,Xiao-Yu Bai

doi:10.1155/2018/6424791

Abstract

Building anti-floating anchors have been increasingly used in recent years, but conventional steel anchors under service conditions are easily subjected to chemical erosion. Glass fiber reinforcement polymer (GFRP) is a promising solution to this problem. In this study, field pullout tests were conducted on three full instrumented GFRP anti-floating anchors in weathered granite. Specifically, the GFRP anchors during pultrusion were innovatively embedded with bare fiber Bragg grating (FBG) sensors to monitor the axial force distribution along depth. It was found that the embedded FBG could reliably monitor the axial force distribution of GFRP anchors. The ultimate pullout force of a GFRP anchor with diameter of 28 mm and anchorage length of 5 m was up to 400 kN. The GFRP anchor yielded at 0.8 m underground. Force distribution and field photos at failure indicated shear failure occurred at the anchor/bolt interface at the end of the tests. The feasibility of the GFRP anti-floating anchor was also verified in civil engineering. Finally, an elastic mechanical model and Mindlin’s displacement solution are used to get distribution functions of axial force and shear stress along the depth, and the results accord with the test results.

Highlights

Building floating issues due to the increasingly larger and deeper underground basement at high water level have attracted wide attention recently
In-depth investigations of glass fiber reinforcement plastic (GFRP) properties including pull-out performance and mechanism compared to ordinary steel anchors suggest (a) GFRP bars could alternate ordinary steel bars in most projects based on model tests and (b) the GFRP bar, owing to lower elasticity modulus, has a larger slippage at failure than steel bars [7]
(d) No pullout force was transferred to 3.5 m underground, highlighting that a critical depth exists for the GFRP anchor

Summary

Introduction

Building floating issues due to the increasingly larger and deeper underground basement at high water level have attracted wide attention recently. The anti-floating anchor, a kind of anti-floating method through connecting the anchor and soil, is widely used to solve these issues owing to its lower cost, shorter construction period, strong stratum adaptability, and less point force than traditional methods (kentledge, anti-floating pile, and drainage) [1,2,3]. Glass fiber reinforcement plastic (GFRP), fabricated by extruding molten glass through an orifice, is one of the most popular alternatives of all fiber reinforcement plastics owing to its lower cost, higher tensile strength, and excellent insulation [6]. In-depth investigations of GFRP properties including pull-out performance and mechanism compared to ordinary steel anchors suggest (a) GFRP bars could alternate ordinary steel bars in most projects based on model tests and (b) the GFRP bar, owing to lower elasticity modulus, has a larger slippage at failure than steel bars [7]. GFRP bars and GFPR bars as anti-floating anchors are still unfamiliar to practicing Chinese engineers

Objectives

Results

Conclusion