Infrastructure for the 21st Century Framework for a Research Agenda (1987) / Chapter Skim
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Appendix
Appendix
Pages 61-100
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From page 61... ...
Appendix Opportunities for Improving Reliability of Public Works Using Nondestructive Evaluation Note: This report was prepared at the request of the Committee on Infrastructure Innovation by a pane} chaired by Committee member Gordon Kino, tenth Stanley Wolf ~ the NRC task coordinator, - d including as other members: Nicholas Casino, National Bureau of Standards, Ga~thersburg, Maryland Robert Crmt, Who, Janney, Ebtner Associates, Inc. Northbrook, Illinois Kelly O'Day, Peer Systems, Inc., Philadelphia, PenneyI,rania Robert Price, Openaka Corp., Inc., Den~rille, New Jersey 61
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From page 63... ...
Status of NDE ~ Selected Public Works Systems Highways Building Systems Water Piping Systems IV. Near-Term Demonstration Project Concept Project Objectives Project Approach Outline of Project Work Plan V. Research Concepts New Hardware Development of User Friendly Systerna Non |
From page 65... ...
Recommendation: A near-term demonstration project must be conducted to verify the effecti~rene" of NDE. Section IV of this appendix proposes coordinated field testing of several commerciaDy mailable and emerging NDE methods ~ order to evaluate their capabilities for providing reliable facility condition informs tion.
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From page 66... ...
Recommendation: Responsibility for promoting NDE within public works must be given to a central organization In order to obtain most effective benefits from NDE. This org~ation must be capable of both fostering NDE "d amunng its relevance.
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From page 67... ...
This effort should be directed towards embedded sensors like fiber optic sensors In new structures, ultrasonic pulse echo (or impact echo) especially applied to concrete, and thermography and ground penetrating radar for undergroundstructures and pow sibly buildings.
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From page 68... ...
NDE can also medicate unexpected and unacceptable plant operating condition that arise, so that appropriate modifications can be implemented. When used as part of an overall reliability strategy, NDE may also allow design and maintenance options not otherwise possible.
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From page 69... ...
Its Widespread use will require techniques such as elective NDE to mo~tor facilibr condition systematicaBy, modem and associated data bases to predict facility detenoration, and Section support methodologies to assist mar~agers in allocating the maintenance and rehabilitation funds. Various NDE methods are already employed within current infrastructure inspection routines, including visual, laser, electrocheniical, and acoustic techniques (ManDing, 1985; Burdekin, et al, Ig86; Brown ~d CaldweD, 1984; Wibon, 1985; C~iforma Dept.
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From page 70... ...
The advances made in the development of NDE methods
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From page 71... ...
71 for the evaluation of highway oysters have been made possible by the concerted efforts of the Fevers Highway Adn~nistration and state highway departments. Little work has been performed directly on NDE inspection techniques suited specifically for city streets which are typically asphalt concrete pavements supported by prepared subgrades.
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From page 72... ...
The major obstacle in the application clef advanced NDE method to steel structures ~ pr~marily one of technology transfer including the unfamiliarity of focal officials with NDE methods. For example, the advances in acoustic imaging that have been made in the medical and germ nautical fields could be adapted for use in inspecting structural steel components.
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From page 73... ...
The presence of moist ture interferes with the ability of some NDE techniques to probe within concrete. Because of these inherent difficulties, the mu jority of developments ~ NDE methods here been in the area of strength determination rather than Baw detection.
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From page 74... ...
Recent studies have demonstrated the feasibility of methods to measure corrosion rates, but further development and field verification are needed. The development of advanced NDE methods to detect zones of delarrunations in concrete bridge decks has received significant support from the Fevers Highway Administration.
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From page 75... ...
For new construction, sensors should be developed which can be embedded In the structure and can be used at a later tune to gain quantitative measures of exulting conditions in structural members. The development of acoustic emission sensors is a step in this direction, but other devices which measure, for example, internal stress, moisture content, permeability, and corrosion potentials should be investigated.
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From page 76... ...
For example, den lamination may be a measure of corrosion promoted by deflection caused by excessive stress. Though all responses are not evident or measurable at once, all should be considered in the building den sign and in the use of NDE methods during building construction and operation.
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From page 77... ...
There is considerable demand for more cost effective NDE methods. Long-term serviceable roofs are a rarity.
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From page 78... ...
Signal processing and the details of data acquisition are of prime importance to NDE methods because huge quantities of information are obtained which may obscure the application if not properly acquired in real time. Cradking of joints in metal structures ~ ~ measure of fatigue or overstress.
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From page 79... ...
Needs for NDE Techniques for Building Structures NDE methods are urgently needed to a - let in the amen ment of building structures. Emphasis should be placed on fieldportable, rugged, user-friendly equipment that provide an on-site or real-t~me analysm.
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From page 80... ...
Application of NDE Methods Evaluation method differ radically between gravity flow and pressure pipes. Corrosion of gravity pipes tulles place primarily on the interior of the pipe by virtue of the fluid being carried, or through lo" of bedding support through exfiItration from the pipe.
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From page 81... ...
Since corrosion invariably occurs on the exterior of the pipe, only instances of incipient failure are detectable by distress seen on the pipe iDtenor. Electric Potential Surveys-corrosion occumng on the exterior of a pipe produces electrical potentials in the surrounding soil.
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From page 82... ...
' Significant advances have been made In techniques for locating pipelines and for leak detection in pressure lines. However, surface survey techniques are needed to locate areas of mfiItration and exfiItration In gravity Ares, and techniques are required for detecting small leaks In large pressure lines.
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From page 83... ...
NEAR-TERM DEMONST1"TION PROJECT Concept The NDE pane} proposes a demonstration project which would involve coordinated field testing of several com~nerciaBy available NDE methods in order to evaluate their capabilities to provide reliable facility condition Information. This approach should be a more persuasive demonstration of the effectiveness of NDE than separate research and development projects or ~ isolated field demonstration of individual techniques.
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From page 84... ...
A detmIed work ply must be developed which specifies the criteria to be used in selecting the actual sites, the NDE techniques to be investiga - , the procedures to be used to ~rer~f~r the NDE results, study report requirements, and provisions for recommeIldatiom for future studies. Site selection should include locales representing the ~rariou~ climate, material, age, snd defect characteristics of public works
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From page 85... ...
Standard data collection procedures and recording format procedures should be developed to aid in evaluating and comparing aD baseline and NDE data snd test results. For each test site, municipal and utility infrastructure agencies win be requested to provide detailed facility information which will serve as baseline condition information.
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From page 86... ...
Improved NDE hardware and software for infrastructure system, along with greater knowledge of the physical phenomena controlling deterioration of these systems, make it timely to d~ develop a systems strategy for using NDE within an overall reliability framework. Many of these new ideas could be tried out In the laboratory on concrete samples and in the field.
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From page 87... ...
It is apparent that the results obtained with such systems need to be evaluated on known structures, and better proce~mg of the information ~ required. Fiber Optics Fiber optic semors have the great ad~rantage that they car be up In an environment In which there ~ strong electromagnetic and vibrational interference.
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From page 88... ...
But first, a better system strategy or framework for failure analysis, NDE usage, and determination of the reliability of venous types of infrastructure components needed. ondestroctne E~a~ati~ Widen a Systens B.eliabilit~r Strategy The most effective manner for incorporating NDE into inspection routines is to start from an opera reliability strategy for promoting continuous service or product availability from pub kc works.
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From page 89... ...
It is anticipated that unproved reliability strategies would be justified for several cases~amm, central crater mans ~ water delivery systems, streets ~d underground utility comport ~ urban areas, among others. VL ~3T1TUTION" NE1:DS Several Dues anse in the diffusion of the status ~d future directions of nondestructive evaluation for specific infrastructure projects.
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From page 90... ...
However, the level of expertise required for some specialty NDE methods, and the equipment for these methods, may be provided more effectively by personnel operating out of regional centers rather than within each utility. Such regional groups would genre as a conduit of information to and from the central organization descnbe.d above to brag both problems and solutions to the attention of appropriate persons.
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From page 91... ...
In contrast to the deficit ~ initial training programs, there appears to be ample number of refresher courses on NDE methods. ODE Standards in order to consistently apply NDE methods, standards have to be established for their use.
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From page 92... ...
The direct obeenration of the sound emitted Tom a water or gas leak con be a very powerful and simple nondestructive evaluation technique. Acoustic Resonance Methods: A common method for finding structural flaws, such as the presence of delaminations or of cracks in metal structures, ~ to tap the structure with a hammer and listen for the resonant vibration.
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From page 93... ...
Such tracers are inserted into a pipe under pressure, and their leakage ~ used to detect the presence of cracks. Ground Radar: Short pulse radar techniques have been developed for detecting delamination In bridge decks for locating buried pipes, and for detecting flaws ~ concrete.
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From page 94... ...
At the present tune, the large magnets it needs, along with the sophisticated computer proce - sing required makes the system too sophisticated, bulky ~d expensive to be applied to infrastructure amen meet. However, this may change.
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From page 95... ...
Pulse echo method are commonly used for finding faults such as Roil and cracks In metal structures. Such techniques are being developed with relatively low frequency pulses for ex=TnT.~ng concrete.
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From page 96... ...
N N N N Correlation Water Leak Testing N N N N N Eddy current G (surface) N N N N Ground radar G N N N G Magnetic Field Measurements F N N N F Displacement (Gage)
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From page 97... ...
N N N F N Acoustic Emission N N N N G Correlation Water Leak Testing N N N N G Eddy current N N N G N Ground radar N N N G F Magnetic Field Measurements N N N F N Displacement (Gage) N N G N N Strain gage N N G N N Dye penetrant N N N N N Odor sensor N F N N G Chemical N G N N F Le~c detection N N N N G Electrocheniical Methode G F N N N NMR N G N N N N G G N N
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From page 98... ...
Institutiom Conduct~g R - earch and De~relopment in Nondestnactive E`raluation Areas of Effort Representati~re Examules of NDE Technioue De~relonmcnt Institutions Grou~d Conductin ~Penetrat~g R&D on NDE Acoustic Electroma~rneticThermo~raDhic Radar Rockwell Science Center X X Jones Associates X United Tech. Research Center X Schlumberger X Southwest Research Institute X XX Concrete Technology Laboratory X Wiss, Janney, Eletner Assoc.
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From page 99... ...
Institutione Conducting Research and De~relopment in Nondestructi~re E,raluation (continued) Areas of Effort Representati~re Examples of Institutions Materials Charactensation ~rith NDE Methods Conductin~r Pobmer Geotechnical R&D in ND E Met ale Ceramice C'omPosites Concrete _S tructure Rockwell Science X X X Center Jones Associates X United Tech.
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From page 100... ...
Institution Conducting Research Ad De~relopment in Nondestnacti~re Evaluation (continued) Areas of Effort Reoresentati~re Examples of Institutions Conducting R&D on NDE Aircraft Enemy Plants Infrastructure Building Component _S~rstem Characterization with NDE Methods Rockwell Science Center X Jones Associates X United Tech.
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