Reproduction of Rebar Mesh Arrangement Inside Concrete Bridge Deck from
Ground Penetrating Radar Volume Images by 3D DFT
Abstract
Aging of infrastructures has been a worldwide issue, and cost saving by
shifting to preventive maintenance is urgent. Especially, damage
detection of concrete bridge decks is one of the most important
subjects, because of the significant repair costs due to its complicated
structure. Rebars are the fundamental components of bridge decks, and
they often become the trigger of bridge decks’ damages. Previous
researches have been focused on detecting the locations of rebars in
cross section images acquired by single-channel ground penetrating radar
(GPR), however, no research has reproduced 3D rebar mesh arrangement
from radar volume images acquired by multi-channel GPR.This paper
proposes a method that reproduces 3D rebar mesh that contains the data
of vertex location and reflection time from radar volume images. Real
scale bridge deck specimens were created in this study and reflections
of electromagnetic waves were observed utilizing an on-vehicle GPR. In
the proposed method, 3D filtering based on the 3D DFT theory for the
noise reduction was applied. Also, automation in detection of the rebar
depth was achieved focusing on edges of the images. As a result, 3D
rebar meshes were successfully reproduced with appropriate distribution
rebar spacing. Also, the method was applied to radar data acquired from
a bridge in service. The proposed method effectively functioned for
in-service bridge data, and automatically reproduced the mesh of 21m
length.