Bringing optical metrology to testing and inspection activities in civil engineering

Luis Martins,Maria Do Céu Almeida,Álvaro Ribeiro,João Alves E Sousa

doi:10.21014/acta_imeko.v10i3.1059

Abstract

Optical metrology has an increasing impact on observation and experimental activities in Civil Engineering, contributing to the Research and development of innovative, non-invasive techniques applied in testing and inspection of infrastructures and construction materials to ensure safety and quality of life. Advances in specific applications are presented in the paper, highlighting the application cases carried out by LNEC (the Portuguese National Laboratory for Civil Engineering). The examples include: (i) structural monitoring of a long-span suspension bridge; (ii) use of close circuit television (CCTV) cameras in drain and sewer inspection; (iii) calibration of a large-scale seismic shaking table with laser interferometry; (iv) destructive mechanical testing of masonry specimens.Current and future research work in this field is emphasized in the final section. Examples given are related to the use of Moiré techniques for digital modelling of reduced-scale hydraulic surfaces and to the use of laser interferometry for calibration of strain measurement standard for the geometrical evaluation of concrete testing machines.

Highlights

Optical Metrology has a large scientific and technological scope of application, providing a wide range of measurement methods, from interferometry to photometry, radiometry and, more recently, to applications using digital, video and vision systems, which combined with computational algorithms, allow obtaining traceable and accurate measurements
The knowledge of these spatial coordinates supported the calculation of the scale coefficient in each acquired image, since the measurement referential is placed in a static region of the experimental setup
This paper describes relevant contributions of Optical Metrology when applied in different testing and inspection activities in Civil Engineering, providing significant added-value in decision-making processes

Summary

INTRODUCTION

Optical Metrology has a large scientific and technological scope of application, providing a wide range of measurement methods, from interferometry to photometry, radiometry and, more recently, to applications using digital, video and vision systems, which combined with computational algorithms, allow obtaining traceable and accurate measurements. Increasing accuracy of optical measurement instruments creates new opportunities for applications in Civil Engineering, namely, for testing and inspection activities These new methodologies open broader possibilities in Civil Engineering domains where dimensional and geometrical quantities are major sources of information on infrastructures and construction materials. The applications described emphasize the role of digital and optical systems, as a basis for robust techniques able to provide measurement estimates for dimensional quantities, replacing conventional invasive measurement approaches To illustrate these achievements, results of R&DI in the Civil Engineering context are presented, including examples of application in: (i) structural monitoring of a long-span suspension bridge; (ii) drain and sewer inspection using CCTV cameras; (iii) calibration of a large-scale seismic shaking table with laser interferometry; (iv) destructive testing of masonry specimens

OVERVIEW OF OPTICAL METROLOGY

STRUCTURAL MONITORING OF A LONG-SPAN SUSPENSION BRIDGE

DRAIN AND SEWER INSPECTION USING CCTV CAMERAS

DESTRUCTIVE MECHANICAL TESTING OF MASONRY SPECIMENS

Findings

CONCLUSIONS