U.S. NATIONAL SCIENCE FOUNDATION
Grant No. ECE - 8703452
Edited by
M.S. Agbabian and S.F. Masri
Department of Civil Engineering
UNIVERSITY OF SOUTHERN CALIFORNIA
Los Angeles, California 90089-0242
February 1988
Reproduction as a whole or any part therof prohibited except by permission of the copyright owner. The statements, opinions and conclusions expressed in this publication are those of the authors and not necessarily those of the University of Southern California and its co-sponsoring organizations.
This International Workshop on Nondestructive Evaluation for Performance of Civil Structures was held at the University of Southern California on 2 and 3 February 1988. Seventy-nine participants with a variety of technical backgrounds participated in the formal presentations and discussions covering current practices, research, and future needs. These Proceedings present the technical papers and summary statements of the formal discussions. All Workshop expenses were supported by the National Science Foundation through Grant CE - 8703452 to the University of Southern California. This financial support and the personal efforts of Dr. John B. Scalzi of the NSF are gratefully acknowledged. We are indebted to all participants whose attendance and contributions helped us focus on the important and critical issues of nondestructive evaluation technology, and whose enthusiasm for acting on the recommendations of the workshop will provide the motivation to complete the tasks that are before us. The assistance of Mrs. Samia Issa and Mr. Robert Nigbor in the various phases of the Workshop is greatly appreciated. The opinions, findings, conclusions and recommendations expressed in these Proceedings are those of the individual contributors and do not necessarily reflect the views of the NSF or other government agencies. Mihran S. Agbabian Sami F. Masri University of Southern California ACKNOWLEDGMENTS
Acknowledgement iii Program 2 Purpose of the Workshop 6 Welcoming Remarks 8 Working Group Summaries Group 1: Global Structural Diagnostics 14 Group 2: Physical Properties 20 Group 3: Physical Defects 25 Group 4: Environmental Degradation 29 Invited Papers Paul Höller & G. Dobmann: ``Nondestructive Evaluation for Performance 37 of Civil Structures -- An Overview of Activities in the Federal Republic of Germany" Teruo Kishi & Masayasu Ohtsu: ``Nondestructive Evaluation of 63 Civil Structures in Japan" Robert Green, Jr.: ``Current and Emerging Techniques 81 for the Nondestructive Evaluation of Civil Structures" John Fisher & John Wood: ``Experience with Bridge and Building Structures 101 and Opportunities for NDE" Submitted Papers Agbabian, M.S., Masri, S.F., Miller, R.K., Caughey, T.K., ``Non-Destructive 123 Evaluation of Structural Changes on the Basis of Experimental Measurements" (Abstract) Ahmad, S.A., Cheng, S.S.M., Peaker, K.R., ``Non-Destructive Evaluation 124 of Cast-In-Place Piles by Sonic Integrity Testing in the Toronto Area" (Presented by P. Anderson) Aki, K., ``Seismic Wave Attenuation in the Earth's Crust 133 as a Diagnostics of Seismicity Level" (Abstract) Aktan, A.E., Hogue, T.D., Hoyos, A., ``Regional 135 Identification of Civil Engineered Structures" Anderson, P.D., ``Pavement Rehabilitation by Non- 181 Destructive Dynamic Deflection Testing" Beck, J.L., ``Probabilistic System Identification in the 192 Time Domain" (Abstract) Beliveau, J-G, Huston, D., ``Modal Testing of Cable-Stayed 193 Pedestrian Bridge" Bodig, J., Goodman, J.R., ``NDE for Performance of Wood 203 Structures" Datta, S.K., ``Ultrasonic Quantitative Nondestructive 216 Evaluation of Engineered Structures" (Abstract) Flesch, R.G., Kernbichler, K., ``A Dynamic Method for the 218 Safety Inspection of Large Prestressed Bridges" Hawkins, N.M., Nobuta, Y., ``Acoustic Emission Technique 231 to Detect Debonding Between a Reinforcing Bar and Surrounding Concrete" Iwan, W.D., ``Predicting Damage and Future Earthquake 241 Performance of Buildings Based on Data from Past Earthquakes" (Abstract) Kam, T-Y., ``Nondestructive Evaluation of Fatigue Life 242 of Existing Structures Under Random Loads" Kingsley, G.R., Noland, J.L., ``Nondestructive Methods 252 for Evaluation of Masonry Structures" Kobori, T., Kanayama, H., Kamagata, S., ``On Active 262 Seismic Response Controlled Structures - Dynamic Intelligent Building System" (Presented by M. Ohtsu) Lee, A-C, Chen, J-H, ``Modal Parameter Estimation 272 for Randomly Excited Structural System with Unmeasured Input" Limaye, H.S., ``Laboratory and Field Testing of Concrete 282 Using Impact-Echo Technique and an FFT Analyzer" Livingston, R.A., Chang, L., Evans, L.S., Trombka, J.I., 292 ``The Application of the Neutron Probe to the Nondestructive Evaluation of Building Condition" Mal, A.K., Bar-Cohen, Y., ``Ultrasonic NDE of Bonded Solids" 299 Maser, K.R., ``Detection of Leaking Fluids in Storage 309 Facilities and Pipelines" McCabe, W.M., Nobuta, Y., ``Detecting Rock Bolt and 341 Reinforcing Bar Debonding Using the Acousto-Ultrasonic Method" McGogney, C.H., Green, R.E. Jr., ``Ultrasonic Residual 348 Stress (Strain) Measurements in Civil Structures" (Abstract) McNiven, H.D., ``Constructing a Mathematical Model for 351 Constitutive Properties of Masonry" Murphy, J.C., Srinivasan, R., Lillard, R.S. ``Magnetic 361 Corrosion Sensing on Larger or Inaccessible Structures" Ohtsu, M., ``Acoustic Emission and Diagnostic System 377 for Cracks in Concrete Structures" Olson, L.D., ``Case Histories of Nondestructive Evaluation 387 of Environmental Degradation Effects on Concrete and Steel Structures" Thornton, H.T. Jr., Alexander, A.M., ``Nondestructive 394 Testing Systems for Evaluating Civil Concrete Structures" Thornton, H.T. Jr., Alexander, A.M., ``Ultrasonic Pulse- 411 Echo Delamination Detection in a Simulated Parking Garage Deck Slab" Appendices Appendix A: Workshop Announcement 419 Appendix B: List of Participants 425 TABLE OF CONTENTS
For several years, a task force of the American Society of Civil Engineers has been working diligently to prepare a manual on the ``Quality in the Constructed Project." The manual emphasizes the team effort to achieve quality in the construction project, and it points to the fact that ``lack of quality in the construction project invariably results in a higher total cost" because of shorter useful life of the structure or a high maintenance cost. Another factor of concern, of course, is safety against failure or malfunction. What can be done to maintain quality after the construction process is completed? How serious are the degradation of structures as a function of time and design flaws that have gone undetected? Answers to the second question will trigger the initiation of a program for preventive maintenance or for repair and rehabilitation and will help maintain the ``quality of the constructed project." In the last decade we have seen the emergence of nondestructive evaluation (NDE) professionals who, collaborating with other professionals, are making important contributions to the quality of the constructed facility. NDE is an interdisciplinary technology. It uses mechanical, electrical, acoustic, nuclear and optical techniques for the evaluation of the integrity of structures. NDE of civil structures, as compared with NDE of aerospace or mechanical structures, has not as yet adopted all available technology. There are good reasons for this. Quality control of mechanical products in large numbers (e.g. valves) or maintenance checkups of aerospace products (e.g. jet engines), use techniques that are geared to automated procedures for which manuals are written and guidelines are closely followed in the plant. No such procedures are standardized for buildings, bridges, dams, power plants, and other civil structures. The tools are there to be used by the professional, but he has to apply them to a particular structure in a particular environment. We believe that there are three areas of activity that engineers should pursue vigorously in order to elevate NDE to a more mature technology for application to civil structures. These are: (1) expanding the scope of research in NDE technology that is particularly applicable to civil structures; (2) transferring technology from aerospace, mechanical, and other disciplines to civil engineering; and (3) disseminating knowledge and application standards to the practising engineers. It is for this purpose that this international workshop on Nondestructive Evaluation for Performance of Civil Structures has been convened. The specific needs of the civil engineering profession and how those needs can be met are discussed from an interdisciplinary perspective. Engineers and scientists from other disciplines have joined civil engineers in this workshop for the purpose of arriving at joint recommendations. The working groups and the presented papers address issues on global structural diagnostics, physical properties, physical effects, and environmental degradation. They provide the engineering profession with the information that will, hopefully, lead to the standardization of monitoring procedures, measurement criteria, and evaluation methodology for NDE of civil structures. The University of Southern California undertook the task of convening the workshop and publishing the proceedings. The inspiration and guidance, as well as the funding, have come from the National Science Foundation through the Systems Engineering for Large Structures Program of the Critical Engineering Systems Division. Dr. J.B. Scalzi, Program Director, has identified a number of ``critical" areas -- water supply systems, highways and bridges, buildings, sewer systems, wastewater treatment plants, ports, and dams -- which constitute the infrastructure of the nation, and for which NDE techniques have to be applied so that their continuing deterioration is prevented through renovation and rehabilitation. This is a monumental task for the civil engineering profession. The technological dimensions are many, and we, as civil engineers, welcome our colleagues from other disciplines for a joint effort to reach our goal. Mihran S. Agbabian Sami F. Masri University of Southern California PURPOSE OF THE WORKSHOP
Ladies and gentlemen, welcome to this International Workshop on Nondestructive Evaluation for Performance of Civil Structures. This is the first workshop concerned with this new and multidisciplinary field for civil engineers and one which I feel certain is destined to become more popular as a research activity in the years ahead. As a nation we see that our public works have reached their designed maturity and are showing definite signs of wear and tear and in many instances have gone far beyond their expected life of usefulness and safety. For example, we all know that our highway and railroad bridges ranging from 50 to more than 100 years old are still performing their intended function in spite of increased loads and excessive use. The fact that these bridges are still in actual full time use is a great testimony to the bridge engineers of those early days of our country's development and to their vision beyond these years to design for longevity and safety. Although we still hold safety uppermost in our designs, longevity is something we have since forgotten. Now, the time is upon us to assess the operational and physical condition of our public work facilities, which will require the talent, the ingenuity, the imagination, the patience and the wholehearted cooperation of several varied disciplines in order to develop the proper tools of nondestructive evaluation for the performance of public work facilities. To accomplish this assessment is the objective of this workshop. Dictionaries tell us that a workshop is a gathering of highly qualified experts, such as yourselves, in a particular field, to interact with one another to accomplish anyone of many purposes. These are sharing ideas and information, creating a research agenda or defining the current state of the art in a particular disciplinary field. I note that this workshop has undertaken to tackle all three objectives of a workshop. I can visualize three types of basic equipment which may be needed and, of course, there could be more. I see a need for equipment to evaluate current conditions of in-place material strength, another to serve as inspection type tools, and yet another for quality assurance during manufacturing and construction processes. Reading the program I note that the workshop will consist of four categories -- global structure diagnostics, physical properties, physical defects and environmental degradation. I believe these topics are well chosen and should lead to the specific definitions of research activities which are sorely needed at this time. I would like to emphasize that the usual workshop ``laundry list" of general topics and loosely phrased project titles serve no valid purpose because they merely state that more research on everything is needed. While we already know that, we must be selective and explicit. I would like to offer for your consideration the thought that the research needs statements could serve as basic descriptive material suitable for an NSF program announcement inviting solicited proposals on specific items. I further suggest that we should not look at the idea of trying to fit the currently available equipment to our needs, but rather, we should describe our needs in terms of what the equipment should do. This may generate a whole new set of equipment which will also help to serve our balance of payments. Patents are available through NSF research endeavors; and who knows, our next engineer millionaires may be from this group of highly motivated innovative teams. The descriptions of the type of data and information which we would like to know are well within the four categories selected for your consideration at this workshop. I would like to suggest further that in your group discussions and deliberations you seriously consider the use and impact of robotics, automation, remote sensing and recording of data in real time combined, of course, with ease, economy and simplicity and use of interpretation of data. Because I have outlined much of what you are being asked to do here you might rightfully ask: why does NSF sponsor workshops? A workshop is useful when a new technical program is created or when an existing one takes on a new direction. It becomes expedient to learn the thoughts and ideas of the research community who is specifically involved in the general field. They are the persons most knowledgeable in the subject and are in the best position to outline a national program of research. I'd like to repeat -- a national program of research. It is they who will be performing the research pursuits. NSF with taxpayer money assists and administers the program. Therefore, one may expect that the research results will be of proportional benefit to the country. The workshop will be incomplete without a good published proceedings report containing the state-of-the-art papers, and a carefully planned research agenda. They will still be incomplete if the proceedings are not disseminated widely to other researchers who may be interested in the subject area. These actions are in agreement with the special project which we recently completed for NSF by three junior-year students as part of their mandatory requirements for graduation. NSF engaged the students to perform the project. They are from Worcester Polytechnic Institute in Worcester, Massachusetts. The title of the project is ``Alternative Effective Engineering Workshops". The objective of the project was to examine current procedures and practices of conducting workshops and then to make recommendations for a more effective workshop. They interviewed many previous participants, some of you may be among them, and coordinators of NSF workshops and also queried the program directors of the engineering directorate at NSF. Based on this information, they developed conclusions and recommendations and I'd like to quote from their report. Conclusion: Welcoming Remarks by Dr. John B. Scalzi
From this they developed a couple of recommendations. To maximize the effectiveness of the workshop based on these conclusions they recommend the following:
- An engineering workshop is a gathering of experts who work together to answer three questions. Where is the field now? Where is it going? How will it get there?
- There are many possible methods for evaluating individual workshops and no one method is best. But if NSF wishes to improve its workshop programs, it needs a system by which to evaluate the workshop.
- Information dissemination is a problem nationwide, not only for the government but for industry as well. NSF's present policy of completely delegating to the grantee the responsibility of disseminating information from workshops has not always been adequate.
- Workshops can and should be used as planning sessions for formulating five to ten year research programs.
- NSF should continue to employ grants as its primary mechanism for funding workshops, but stricter conditions must be placed on the grants to protect NSF's interest.
The students were Michael Dezzani, George Hosey and James C. Boyd. I would like to reiterate that these conclusions and recommendations for a workshop were developed by junior year students and indicate a very critical review of current practices in the conduct of workshops. Their recommendations are worthy of implementation. I ask you to think of these findings in your deliberations during this workshop. Thank you very much.
- Employ a three-phase system for the evaluation of workshops. This would be to (i) ask participants through a questionnaire what they think of the workshop. (ii) Determine the number of proposals received related to the workshop theme following the workshop. (iii) Determine the extent to which the field of science has progressed as a result of the workshop.
- Develop a mandatory policy for grantees to follow in the dissemination of information resulting from the workshop. The policy should include distribution of four to six page summaries of the proceedings report.
- Employ the following system for a five to ten year research program in workshops:
- A steering committee; select participants; set the long-term research agenda in the first workshop; reconvene the group every two to three years to refocus, abolish or continue the agenda; recycle this operation every five to six years.
- The NSF general grant conditions to include workshop participant list and change of principal location as items requiring NSF approval. This will increase the Program Director's control over the workshop he sponsors and will help to protect NSF's interests.
International Workshop on OBJECTIVE: This National Science Foundation--sponsored workshop will convene civil/structural engineers and scientists engaged in nondestructive evaluation research to investigate the feasability of adapting proven techniques and to consider new techniques that are under development for possible application for NDE of civil structures. Work in progress will be discussed, specific needs of the Civil Engineering profession will be identified, the advantages and limitation of NDE methods in acoustics, photonics, fiber optics, image processing, electrical resistivity, and other areas of technology will be evaluated for the purpose of arriving at recommendations for possible applications and for future research. FORMAT: The first day of this two--day workshop will feature invited papers and summary reports. Ample time is scheduled for participant questions and interactions. The second day of the conference will consist of workshop panels that will discuss specific topics related to civil structure nondestructive evaluation, culminating in a detailed, prioritized research plan in addition to NDE equipment specifications for use in civil structures. PROCEEDINGS: Post conference proceedings will include invited lectures, extended abstracts, research needs, and workshop conclusions. PAPER SUBMITTAL: Individuals wishing to present a paper on pertinent topics are requested to submit an extended summary of their paper by December 1987. In particular papers in the following areas are solicited:NONDESTRUCTIVE EVALUATION FOR PERFORMANCE OF CIVIL STRUCTURES
2-3 February 1988 Davidson Conference Center University of Southern California Los Angeles, California