Experimental Investigation of a Self-Sensing Hybrid GFRP-Concrete Bridge Superstructure with Embedded FBG Sensors

Yanlei Wang,Yunyu Li,Mingmin Cao,Jianghua Ran

doi:10.1155/2012/902613

Abstract

A self-sensing hybrid GFRP-concrete bridge superstructure, which consists of two bridge decks and each bridge deck is comprised of four GFRP box sections combined with a thin layer of concrete in the compression zone, was developed by using eight embedded FBG sensors in the top and bottom flanges of the four GFRP box sections at midspan section of one bridge deck along longitudinal direction, respectively. The proposed self-sensing hybrid bridge superstructure was tested in 4-point loading to investigate its flexural behavior and verify the operation of the embedded FBG sensors. The longitudinal strains of the hybrid bridge superstructure were recorded using the embedded FBG sensors as well as the surface-bonded electric resistance strain gauges. The experimental results indicate that the embedded FBG sensors can faithfully record the longitudinal strains of the hybrid bridge superstructure in tension at bottom flanges and in compression at top flanges of the four GFRP box sections over the entire loading range, as compared with the surface-bonded strain gauges. So, the proposed self-sensing hybrid GFRP-concrete bridge superstructure can reveal its internal strains in serviceability limit state as well as in strength limit state, and it will have wide applications for long-term monitoring in civil engineering.

Highlights

A major concern for many bridge superstructures is the significant reduction in durability and life expectancy caused by the corrosion of the reinforcing steel and the corresponding deterioration of the concrete
The advantages of this concept include: (1) corrosion resistance for steel-free design; (2) initial costs reduction due to the effective use of concrete; (3) lightweight; (4) reduction of local deformation under concentrated loads that is found to be a problem in all-fiber-reinforced polymer (FRP) bridge; (5) no joints between decks and girders; (6) significant understanding of the bridge behavior that can be obtained by testing of individual beams; (7) the ability to be well understood by bridge engineers
Eight fiber Bragg grating (FBG) sensors were designed to be embedded into the outer laminate at the top and bottom flanges of GFRP part at midspan section of one bridge deck along the longitudinal direction (shown in Figure 3(b)), respectively

Summary

Introduction

A major concern for many bridge superstructures is the significant reduction in durability and life expectancy caused by the corrosion of the reinforcing steel and the corresponding deterioration of the concrete. These problems are accelerated by the application of deicing salts in cold area. Smart (or self-sensing) structures are the structures which contain the built-in sensing device to continuously monitor the current state and serviceability of the structures This is referred to as “passive” smart structures, which have many applications in civil engineering [18, 19]. The flexural behavior of the hybrid bridge superstructure will be investigated, and the monitoring performance of the embedded FBG strain sensors in the hybrid bridge superstructure will be examined

Proposed Hybrid GFRP-Concrete Bridge Superstructure System

Experimental Program

Test Results and Discussions

Conclusions