Non-destructive Testing and Evaluation of Civil Engineering Structures

Jean-Paul Balayssac, Vincent Garnier

• Publisher: ISTE Press - Elsevier
• Year: 2017
• ISBN:
  9780081023051
• Topic: Technology & Engineering
• Subtopic: Civil Engineering
• Index: Technology & Engineering

The non-destructive evaluation of civil engineering structures in reinforced concrete is becoming an increasingly important issue in this field of engineering.

This book proposes innovative ways to deal with this problem, through the characterization of concrete durability indicators by the use of non-destructive techniques. It presents the description of the various non-destructive techniques and their combination for the evaluation of indicators. The processing of data issued from the combination of NDE methods is also illustrated through examples of data fusion methods.

The identification of conversion models linking observables, obtained from non-destructive measurements, to concrete durability indicators, as well as the consideration of different sources of variability in the assessment process, are also described. An analysis of in situ applications is carried out in order to highlight the practical aspects of the methodology.

At the end of the book the authors provide a methodological guide detailing the proposed non-destructive evaluation methodology of concrete indicators.

• Presents the latest developments performed in the community of NDT on different aspects
• Provides a methodology developed in laboratory and transferred onsite for the evaluation of concrete properties which are not usually addressed by NDT methods
• Includes the use of data fusion for merging the measurements provided by several NDT methods
• Includes examples of current and potential applications

1

Introduction

Jean Salin; Jean-Paul Balayssac; Vincent Garnier

Abstract

The purpose of this introductory chapter is to present the history of the use of non-destructive evaluation methods in industry. It also highlights that in the majority of situations, with the crucial exception of Civil Engineering, developments in this area respond to normative or regulatory constraints. To demonstrate this, we will refer to examples provided by pressure equipment, wind energy, aeronautical sectors, and ski lifts. Thereafter, we will focus on the context of Civil Engineering structures and examine some of the reasons for which the use of Non-Destructive Evaluation (NDE) has not experienced the same level of growth as that seen in other industrial sectors, even if resources are available for applications, many of which are also regulated. A census of the requirements for Non-Destructive Evaluation for Civil Engineering structures will also be carried out, by resituating it within the broader context of monitoring and asset management.

Keywords

Absence of standards; Aviation; COFREND; Existing regulations; Ski lifts; Socio-economic context; Wind energy sector

The purpose of this introductory chapter is to present the history of the use of non-destructive evaluation methods in industry. It also highlights that in the majority of situations, with the crucial exception of Civil Engineering, developments in this area respond to normative or regulatory constraints. To demonstrate this, we will refer to examples provided by pressure equipment, wind energy, aeronautical sectors, and ski lifts. Thereafter, we will focus on the context of Civil Engineering structures and examine some of the reasons for which the use of Non-Destructive Evaluation (NDE) has not experienced the same level of growth as that seen in other industrial sectors, even if resources are available for applications, many of which are also regulated. A census of the requirements for Non-Destructive Evaluation for Civil Engineering structures will also be carried out, by resituating it within the broader context of monitoring and asset management.

The primary objective of this book is to transfer collaborative research carried out on Non-Destructive Evaluation of concrete structures over the last twenty years into the technological realm. The second objective is to show the originality of the positioning of such studies aiming to characterize concrete indicators, in comparison to those of other international teams who use Non-Destructive Evaluation for imaging.

1.1 The beginnings of NDE

Since the dawn of time, mankind has carried out Non-Destructive Evaluations (NDE) using sensory tests (eyesight, hearing or touch). Modern non-destructive evaluations attempt to bring a certain level of objectivity to the evaluation of the condition of a system, by using increasingly sophisticated technologies, while also constantly pushing the limits of physics, technology, and analytical skills as far as possible. The history of techniques shows that the development of non-destructive evaluation tools has always been subject to pressure in terms of ensuring equipment safety, but this pressure is also of an economic, social, and even political nature.

To provide an example of this, medical imaging by x-ray broke into the mass-market thanks to developments made by Marie Curie during World War 1, which sought to deal with the care needs for the thousands of soldiers wounded in battle [DEM 07]. The work carried out by the physicist Röentgen, as well as the doctors and dentists that supported her, enabled her to create non-laboratory mobile units; the “portability” of medical industry techniques immutably becoming the vehicle for development of a number of NDE techniques, from ultrasonic medical echography in the 1980s, to multiple-element sensors, normalized in 2015 for the purpose of examining metal parts. Sonar¹ for the detection of surface ships and submarines was also developed during this period. The development of radar technology² was initiated in 1904 with the purpose for ships to use it to avoid collisions and it was perfected and industrialized during the Second World War, particularly thanks to the invention of the magnetron. Physical principles defined in previous decades are; x-Ray emissions, silver-based photographic tools and radioscopy, ultrasound propagation, piezoelectricity, and the laws of electromagnetism respectively. As such, the principal technique at work can be summarized by Figure 1.1.

Figure 1.1 Technical principle of “observation”

The object under analysis is situated at the center of this technique, either on the surface or in volume, in order to find disparities or anomalies. We use a transmitter or source to “illuminate” the object, which for sonar may be the noise emitted by the ship itself and a hydrophone receiver. In the simplest case, this being visual examination, the source is light and the receiver the eye. Information resulting from this examination provides an indicator that can be used for diagnosis.

1.2 Industrial development of NDE

1.2.1 Pressure equipment

Industries and railways have been developed with the use of steam engines ever since the mid 19th Century. The increasing number of accidents related to the use of steam, of which pressure, volume and temperature increase regularly, led States to implement legislation in order to regulate pressurized steam equipment by any means possible. In France, legislation was implemented in October 1907, before publication of the ministerial circular of 26th January 1926, concerning “steam equipment for the preparation of coffee and cooking food”, followed by the broader decree of April 2nd 1926. It included a deterministic approach based on the laws of physics (Gay Lussac) and mechanics, more specifically resistance to rupture or fatigue, supported by ten-year hydraulic testing during which a visual examination of all equipment was carried out. It was in force until the European Directive 97/23-CE and decree 99-1046 of 13th December 1999 were transposed into French law. Since its implementation in 1926, the regulatory framework has become enriched by feedback accumulated over the years, resulting in legislation such as the decree of January 18th 1943 for gas pressure devices, for example. In practical terms, this concerned refineries, industrial chemical or tire-making plants, steel-making, pipelines, etc.

The decree of 26th February 1974 dealt more specifically with “nuclear boilers”; it was updated and replaced by the decree of November 10th 1999, after publication of the European directive. Addendums relating to the roles of actors were introduced via the Energy Transition for Green Growth Act on August 17th, 2015 (France). In terms of pressure equipment monitoring, the most effective measures used to examine all components (tanks and their welds, pipes, valve bodies, etc.) were integrated into legal texts by Parliament. To meet these requirements, the industry came together to develop codes and standards not only for the design, construction and operation of steam or gas pressure equipment, but also for non-destructive testing of this equipment prior to market entry, followed by monitoring of them when in operation. More than 130 general standards [AFN 14a] were validated at the end of 2014 at European level, relating to visual, ultrasonic, Eddy current, magnetic particle inspection, bleedout, X-ray, gamma radiography, stress-strain measurement, infrared thermography, acoustic emission, and sealing methods as well as those relating to the equipment necessary for their implementation. They are complemented by so-called “product standards”.

In NDE compliance approaches, standards regulating the qualification of techniques implies the need for qualified staff. In France, personal certification (NF EN ISO 9712 - 2012) is maintained by COFREND, a third party organization. Relevant materials are primarily low-alloyed steel, chrome-based alloys, nickel, copper, and assemblies joined by welding, bolting or hoops.

1.2.2 Aviation

Another industrial domain in which NDEs have experienced significant development is that of civil aviation. Having experienced strong growth by the end of the first world war, the aviation industry quickly sought to re-purpose itself within the transport of post and passengers. In France, this process came to fruition as a result of studies prescribed by an order dated November 19th, 1909. It led to implementation of the decrees of June 6th 1919 and 17th September 1919 for technical service organizations and, due to fatal accidents, to the Act of June 30th 1933, establishing, among other elements, “control of materials”. This regulation continued to evolve in order to integrate feedback. In parallel, manufacturers were positioning themselves on an international level with the creation of the International Commission of Air Navigation in 1919, then in 1944 with what became known as the International Civil Aviation Organization. Within this regulatory context, NDE techniques were developed, qualified and normalized specifically for these materials, according to inspection periods, and periods when they were returned to the workshop for “major refit” operations, wherein the systematic replacement of parts was scheduled. This included materials such as aluminum or titanium-based alloys and fiber/polymer composites, with assembly by riveting, bonding and also by welding, but in smaller proportions. In France, the qualification of personnel is conducted by a third party organization within the COFREND framework according to international rules (European standard PR EN 4179 P5-2014 and American standard NAS 410 Revision 4).

1.2.3 Wind energy sector

More recently, the wind energy sector has experienced significant growth. A wind turbine is divided into two major parts depending on its functions and is made up of different materials. The reinforced concrete base upon which a metal pole is usually bolted is the first element of interest. At the top of the tower, the access platform containing all the electromechanical equipment necessary for the production of electricity via wind energy transmitted to the blades in composite materials is the second most significant piece of equipment. In this ultra-co...

Table of contents

• Cover
• Title page
• Table of Contents
• Copyright
• Foreword
• List of Notations
• 1: Introduction
• 2: Ultrasonic Methods
• 3: Electromagnetic Methods
• 4: Electrical Methods
• 5: Electrochemical Methods
• 6: Quality, Uncertainties and Variabilities
• 7: Construction of Conversion Models of Observables into Indicators
• 8: Assessment of Concrete by a Combination of Non-Destructive Techniques
• 9: Applications In Situ
• 10: Methodological Guide
• Glossary
• List of Authors
• Index