A458

"Safety Concrete" – A New Impact-absorbing Concrete for Protecting Buildings, Structures, and Vehicles

Hamlin M. Jennings
Northwestern University
847-491-4858
h-jennings@northwestern.edu

Jeffrey J. Thomas
Northwestern University
847-491-3201
jthomas@northwestern.edu

The objectives of this project are to develop "safety concrete" that will disintegrate into small fragments when subjected to sudden and severe loading.

This project is focused on developing a new type of concrete, dubbed "safety concrete", that will disintegrate into small fragments (rather than fracture into large chunks or just crack) when subjected to sudden and severe loading. The focus is on developing safety concrete for the application of energy-absorbing vehicle barriers.

1) Determine the most desirable properties of vehicle barrier.

2) Conduct statistically designed experiments on the composition, determining the relationships between various components and the properties and performance of the concrete

October 1, 2002 to September 30, 2003

Current Year = $76,928 4-Year Total = $76,928

The results of this research will potentially be commercialized. The safety concrete is expected to be of interest for highway, municipal and other governmental applications.

This type of concrete that disintegrates into small fragments rather than fracturing into large chunks or cracks when subjected to impact loading will prevent or reduce damage to people and property.

Concrete, Barriers (Roads), Safety, Infrastructure

A459

Nondestructive Determination of Early-Age Concrete Properties with an Ultrasonic Wave Reflection Method

Surendra P. Shah
Northwestern University
847-491-7878
s-shah@northwestern.edu

The ultimate objective of this research is to develop a portable instrument, which can measure the in-place compressive strength of concrete in the field. But to develop a robust procedure, it is essential that we understand what we are measuring. Consequently, this project will investigate the industrial application of the wave reflection method as well as research for fundamental understanding of the physical relationships between wave reflection measurements and concrete parameters.

A nondestructive, ultrasonic technique, which measures the attenuation of ultrasonic shear wave reflections from the concrete surface, was developed at the Center for Advanced Cement-Based Materials (ACBM). The focus of this research project is to develop a nondestructive field sensor for in-situ monitoring of the setting, hardening, and strength gain of cementitious materials.

The first phase of the proposed research is aimed at studying the fundamental understanding of the relationship among evolving microstructure, mechanical properties, and ultrasonic wave reflection measurements. The reflection coefficient measured with shear waves can theoretically be related to shear modulus. The development of shear modulus with time is related to how the microstructure of hydrating cement evolves as a result of curing. Experiments are designed to elicit this fundamental understanding. A computer model, which relates microstructure to degree of hydration and elastic moduli, will be developed in partnership with Delft University of Technology. The aim is to develop a model, which can explain the interrelationship among material composition (e.g. water-cement ratio), curing conditions, evolving microstructure, attenuation measurement, and mechanical properties. Professor Jan Achenbach, from Northwestern’s Center of Quality Engineering and Failure Prevention, also suggested the development of this kind of model during the monthly meetings of the Institute research associates.

The second phase of the research will evaluate the industrial applicability of the wave reflection measurements. This step will be accomplished in cooperation with the precast industry. The Precast/Prestressed Concrete Institute is an ACBM Industrial Partner. We will take their recommendation of a local precaster with which to work on a field test of the WRF process. We also have commitments from two other ACBM Industrial Partners, Cemex USA and Holcim, to provide support and coordination for tests with precasters in Colorado and California.

The research can be divided into two parts. The first part, will focus on the fundamental investigation of the relationship between the attenuation of the wave reflections and evolving mechanical and physical parameters of the tested material. This type of research is necessary to understand the mechanism of the wave reflection method and, through this understanding, to further improve the strength prediction procedure. The objective of Phase A is to develop a constitutive model of the wave reflection measurements on cement-based materials. A computer model, which relates microstructure to degree of hydration and elastic moduli, will be developed in partnership with Delft University of Technology.

In the second part, the industrial applicability of the wave reflection method will be evaluated. The first step toward commercial demonstration of the method will be done in cooperation with the precast concrete industry. In precast concrete construction, certain concrete mixtures are repeatedly used under essentially the same conditions for the same application. This protocol provides relatively constant conditions concerning the tested material and the curing procedure, which is advantageous for introducing a new method of strength measurement. Another factor making the precast concrete industry a good place for initial commercial evaluation is their use of formwork that is easily accessible in multiple locations. This accessibility will facilitate placement of the measurement transducers.

October 1, 2002 to September 30, 2003

Current Year = $111,292 4-Year Total = $111,292

Post-doctoral fellow:

This project builds on a prior research project, "Ultrasonic Technique for In-situ Monitoring of the Setting, Hardening, and Strength Gain of Concrete"

Collaboration with the practitioner community, such as cement producers, concrete precasters, and instrument manufacturers, is an important part of this project, since the ultimate goal is to develop a test method that can be applied under field conditions and that will give results yielding a maximum benefit for the construction process. The Precast/Prestressed Concrete Institute is an ACBM Industrial Partner. We will take their recommendation of a local precaster with which to work on a field test of the WRF process. We also have commitments from two other ACBM Industrial Partners, Cemex USA and Holcim, to provide support and coordination for tests with precasters in Colorado and California. The aim of the collaboration with the precast industry is not only to verify the applicability of the wave reflection method to determine the strength development, but also to determine the earliest time of form removal from concrete elements and the time of applying of prestress to precast elements.

The results of the research will be published in appropriate journals to ensure the national and international outreach of the test method. The research work will also be presented on conferences dealing with testing and evaluation in civil engineering. Besides the presentation on national conferences or seminars organized by the Center for ACBM it is planned to attend one international conference to introduce the results to the international research community.

The nondestructive, in-situ testing of early-age concrete properties is a crucial tool for the progress of many construction projects in the building sector. The application of such techniques can establish the earliest possible form removal from concrete construction elements, thereby opening highways to traffic, releasing prestress from steel reinforcement, or applying post-tensioning with greatest efficiency.

Concrete tests, Nondestructive tests, Ultrasonic tests, Infrastructure

A460

Improved Condition Monitoring for Bridge Management

David Prine
Infrastructure Technology Institute
847-491-2873
dprine@northwestern.edu

The objective of this program is to provide bridge owners with a set of advanced NDE tools so that they may better (more quantitatively and with improved repeatability) determine bridge condition, which is the primary input to a bridge management system. These tools will consist of both equipment and procedures to aid in the inspection of critical bridge components.

This project will continue the development of active monitoring technology for our remote monitoring sites, student / faculty support, large bridge instrumentation and testing, and user group activities. The project team’s student / faculty support activities continue to represent a major portion of the total staff time.

Growth of the remote monitoring technology that was started during Year 3 with the Michigan Street Bridge in Sturgeon Bay, Wisconsin continued. Remote monitoring will continue to be a major activity. The web page for our remote site in Sturgeon Bay, WI is now active and represents the model for future remote monitoring efforts.

The numbers of long term sites and applications for remote monitoring technology have continued to expand primarily because this technology addresses a need that is readily recognized by the infrastructure owners. Safe economically practical life extension of critical portions of the infrastructure demands improved condition monitoring and the remote technology provides a solution to this growing need particularly when one considers the added problem of downsizing imposed on the owners and operators by budget shrinkage. The ability to interrogate a remote site without actually sending an inspector out to the site is an obvious improvement over present methods.

A growing problem with the steady increase in the number of remote sites and sensors is the ever-increasing amount of data collected. The process of downloading the data from many remote sites becomes a time consuming procedure and the danger exists that critical data may be missed as it becomes buried in the flood. The automatically updated net site coupled with automated data analysis provides an excellent solution to this growing problem. The data is continually updated and any readings that exceed pre-set limits automatically result in an e-mail being sent to the customer informing him that he should check the data. A secure net site is up and running for the Michigan Street Bridge in Sturgeon Bay and a major activity during the next year will be to integrate all of our remote sites into a net site.

This task is a continuation and expansion of the ongoing efforts in this area. A major portion of the effort will be focused on the continuation of the demonstration and evaluation of the remote monitoring technology that emerged in previous years’ work. We have the Sturgeon Bay lift bridge on an automated net site and plan on converting all of our active sites to this mode during the next year. We anticipate considerable more work using acoustic emission (AE) in the coming year. The Bryte Bend retrofit project, which was delayed during 2002, will go out to bid and work is projected to begin during summer of 2003. Our efforts in this program will consist of applying and further refining the AE technique we developed during the retrofit design and evaluation. We will evaluate approximately 12 to 15 cross-frame connection sites prior to and immediately following retrofit to assess the effectiveness of the retrofit in alleviating fatigue crack growth. This project will also allow us to gain experience with recently acquired waveform pattern recognition software. The AE monitoring will be done in two one-week trips to Sacramento. This project will not produce revenue because of out of state funding difficulties with Caltrans but it will generate considerable in-kind cost match. The steel portion of the retrofit is over 7 million dollars. We have two new task orders from WI-DOT. The first is for a strain gage-monitoring project on two Milwaukee bridges and the other is for long term maintenance on the Sturgeon Bay Bridge. We also anticipate a new master contract with Wisconsin during 2003 to cover an additional two years of emergency task orders.

The user group development work that was started in Year 1 and continues through the subsequent years is a vital part of this program. It continues to provide guidance to the NU researchers and a valuable source of information exchange between bridge engineers from the various states as well as keeping the bridge engineers informed of the developments of our NU researchers. The ever increasing restrictions to interstate travel that are imposed on State and Municipal DoT personnel have caused us to increasingly emphasize forms of communications other than the traditional topical meeting. Specific activities will include the continued application of the H.323 teleconferencing technology to special topical meetings between NU researchers and various deployment partners, participation in various committees and working groups that are organized by other infrastructure and NDE groups, and Internet activities. We have experimented with this technology at three Bridge Maintenance and Inspection Working Group Meetings and results have been encouraging. Both two-way and streaming video broadcasts have been successfully produced. Additionally, we plan to continue to archive selected presentations and make them available for free by mail (CDROM) for practitioners who do not have fast Internet connections available. We will also continue to support the BMIWG meetings with this technology where appropriate.

This task will aid the development and growth of the educational activities started in previous years. We will continue to organize and support educational tours to various infrastructure-related locations (fabrication facilities, historical bridges, construction sites, etc.). Students and faculty are invited to participate in our field test efforts on a regular basis. We have successfully used the freshman engineering design course participants and we plan to continue to utilize this valuable resource. Both ITI and the students receive considerable benefit from these projects. The EDC projects provide these students with valuable hands-on project experience with the potential of greatly expanding the capabilities of our small bridge team staff. Additionally, we also attempt to employ students (either work study or as temporary part-time employees) wherever possible. We also expect to continue to provide support for graduate students who are involved with research activities under the direction of our faculty partners.

October 1, 2002 to September 30, 2003

Current Year = $335,639 3-Year Total = $1,032,284

We will continue to organize and support educational tours to various infrastructure-related locations (fabrication facilities, historical bridges, construction sites, etc.). Students and faculty are invited to participate in our field test efforts on a regular basis.

We also attempt to employ students (either work study or as temporary part-time employees) wherever possible. We also expect to continue to provide support for graduate students who are involved with research activities under the direction of our faculty partners.

During the last year’s effort the emphasis was on development of active monitoring technology for our remote monitoring sites, student / faculty support, large bridge instrumentation and testing, and user group activities. These activities will continue during the coming year. Our current student / faculty activities continue to represent a major portion of total staff time. Growth of the remote monitoring technology that was started during Year 3 with the Michigan Street Bridge in Sturgeon Bay, Wisconsin continued. This year’s efforts have further solidified ITI’s leadership position in this area.

We also expect to continue to provide support for graduate students who are involved with research activities under the direction of our faculty partners.

Two marketable products have emerged from this work. They are an improved acoustic emission bridge monitor (AEBM), and test services. The test services include application of advanced NDE such as AE, Impact Echo, TDR, and strain gauges as well as the installation and maintenance of remote monitoring systems. In year five a new approach to scour monitoring emerged which has achieved acceptance at Caltrans and resulted in a major change in their approach to solving this problem based on the ITI developed technique. This is an excellent example of successful technology transfer.

The current economic downturn has had an adverse impact on the budgets of state transportation agencies, which in turn will negatively impact our revenue. Out-of-state funding has become increasingly difficult to attain. Furthermore decentralization with the accompanying demise of the central DoT office hasn’t helped matters. The decentralization has been accompanied by an increasing dependence on consultants. We have successfully worked with major consulting firms such as Hazlet and Erdal, Wiss Janey Elstner, Michael Baker, Lichtenstein, and recently Hardesty and Hanover. We will continue to pursue and strengthen relationships with these organizations as well as actively pursue new state and municipal partners. A high and growing level of user community involvement is key to maintaining and expanding the market and insuring relevance.

The user group development effort maintains a strong involvement with the user community through meetings. Newsletters, and electronic communications via the Internet have also been very effective. We closely coordinate our user group efforts with the Mid-West Bridge Maintenance and Inspection (BMI) working group.

A major contribution to improved condition monitoring of critical infrastructure has been made through the development of remote monitoring technology under this program. The first application occurred in 1995 in Sturgeon Bay, WI. Since then great strides have been made in system complexity and improved reliability. The numbers of long term sites and applications have continued to expand primarily because this technology addresses a need that is readily recognized by the infrastructure owners. Safe economically practical life extension of critical portions of the infrastructure demands improved condition monitoring and the remote technology provides a solution to this growing need particularly when one considers the added problem of downsizing imposed on the owners and operators by budget shrinkage. The ability to interrogate a remote site without actually sending an inspector out to the site is an obvious improvement over present methods.

Bridge management systems, Infrastructure, Monitoring, Non-destructive testing

A461

Provision of Remotely Controllable, Satellite Connected Web Camera of the Bridge Construction

Charles Dowding
Northwestern University
847-491-4338
c-dowding@northwestern.edu

Roberta Massabò
Northwestern University
847-467-4105
r-massabo@northwestern.edu

The objectives of this project are:

·    Short term: to implement a camera system that will allow undergraduate students to view the construction of the Hoover Dam Bypass Bridge while they are reviewing the design in their structural design class.

·    Long term: develop satellite data communications mechanism to allow ITI to deploy instruments without needing to interact with local utility providers.

This project will test and install a remotely controllable web camera focused on the Hoover Dam Bypass Bridge (or other suitable location) that will allow undergraduate students, as part of their class curriculum, to view the site construction as they review construction designs. It is intended to have the camera installed at the Hoover Dam Bypass Bridge during construction of the new access alignment and pier foundations.

The project will also develop a satellite data communications system that will allow ITI to deploy instruments without needing to rely on local utility providers. Perceptual Robotics cameras will be interfaced with the Tacheon satellite ISP. The project includes utilization of Perceptual Robotics web site services and the project team’s development of ancillary equipment and component integration.

1) A Remotely Operable Satellite Data Communication System (SDC) will be developed through a two-step process.

a. Tacheon satellite ISP equipment will be interfaced with Perceptual Robotics cameras as a demonstration under the direction of Larry Amiot.

b. This system will then be purchased and integrated in Evanston before deployment at the Hoover Dam Bypass Bridge under the direction of Larry Amiot.

2) Test and install camera satellite ISP system.

October 1, 2002 to September 30, 2003

Current Year = $42,358 4-Year Total = $42,358

ITI project "The ICCML as a Novel Teaching Tool to Improve Undergraduate Education and Student Learning of Civil Engineering" (see following project, Center Identifying Number A462) will use this system as part of its civil engineering courseware development project.

The satellite-connected web camera system will enable civil engineering courses to be created that integrate viewing of the construction site with other relevant content for study, such as design documents, project plans, plan changes, etc.

Improved reliability and flexibility for video and data transmission from remote locations will aid in undergraduate civil engineering education and in other ITI projects. For instance, poor to no provision of data connectivity impaired deployment of camera surveillance at the Sturgeon Bay Bridge.

Education and training, Monitoring, Satellite communication, Infrastructure

A462

The ICCML as a Novel Teaching Tool to Improve Undergraduate Education and Student Learning of Civil Engineering

Roberta Massabò
Northwestern University
847-467-4105
r-massabo@northwestern.edu

The objectives of this project have been updated as a result of the findings of the preceding first phase of the project, and are as follows

1. Develop multimedia-supported case study material for undergraduate civil engineering courses based on the use of new technologies in teaching. The courseware will be organized in order to be used within single engineering courses and for integrated laboratories among different courses. The courseware will deal with an in-depth analysis and presentation of large civil engineering projects.

2. Develop a new web site incorporating the case study material. The web site will be highly structured to allow effective learning (see below for basic features of the web site).

3.The coursewsare will be organized in different educational paths developed for different levels of education. The intermediate level educations path will be used as a tool to attract high-school students to the civil engineering profession.

This project is the second stage of an anticipated one and one-half year program to investigate the feasibility of using the Infrastructure Construction and Condition Monitoring Laboratory (ICCML) of the Infrastructure Technology Institute (ITI), its web site, and its remotely operated web-camera as a novel teaching tool to improve undergraduate education and student learning of civil engineering. A new course or new content for existing undergraduate courses within the civil engineering program will be developed with the aim of creating a more effective learning environment and bringing knowledge from the infrastructure / building industry to university curricula. The feasibility of using the ICCML to attract young students from middle school to join civil engineering programs will also be investigated. The existing web site of the ICCML will be improved with the incorporation of new case studies and material.

This second stage of the project will involve the following tasks, which will be worked on in parallel:

1. The basic structure of the courseware will be developed.

2. The material already available at the Hoover Dam Bypass web site (or material collected from other sources if an alternative project location is chosen) will be selected and processed. The material will be organized in modules dealing with: project history; environmental issues and public involvement; project criteria; project alternatives and selection process; surveys and mapping, geotechnical, seismic and wind investigations; bridge preliminary design and bridge type selection.

3. New material will be collected and progressively processed during the year in order to be included in the courseware.

October 1, 2002 to September 30, 2003

Current Year = $67,666 4-Year Total = $79,949

Graduate Research Assistant: Randy Herbstman, graduate student in the Structural Engineering and Materials graduate program of Civil Engineering, will have the opportunity to substantially improve his knowledge of civil engineering, project management and monitoring techniques; to deal with novel teaching techniques; to play an active part in the creation of new content for undergraduate civil engineering courses by bringing into the project a student perspective.

Undergraduate work study student: an undergraduate student will also participate in the project.

This is a continuation of a previous six-month project, and constitutes the last 12 months of an 18-month project.

The results of the project will be used as a vehicle to transfer knowledge from the building / infrastructure industry to undergraduate curricula, and to offer undergraduate students a tool for active learning and the opportunity of being "virtually" present on sites of otherwise restricted construction projects.

The potential of the ICCML, its web site and remotely-operated web cameras is enormous. The cameras can offer remote access to construction sites that would otherwise be restricted. They allow virtual presence on sites of large and interesting construction and retrofitting projects, in different locations in the United States and during critical times of the construction. Free access to the information incorporated in the web site can provide learning opportunities on building and infrastructure design, construction, maintenance and retrofitting, on new monitoring technologies and on management of large projects and public infrastructures.

Education and Training, Civil Engineering, Websites (information retrieval), Infrastructure, Bridges, Construction

A463

Improved Condition Monitoring of Bridges: Nondestructive Evaluation of Foundations

Richard J. Finno
Northwestern University
847-491-5885
r-finno@northwestern.edu

The objectives of this project are to extend the guided wave theory to flexural wave propagation in piles and both longitudinal and flexural waves in embedded plates (representing slurry and soil mixed walls), and to continue refinement and field verification of the guided wave, longitudinal wave identification (LWI) and shear wave identification (SWI) methods.

The purpose of this project is to develop methods to non-destructively evaluate the condition of existing deep foundations and bridge piers. With previous support, a drilled shaft test section for non-destructive evaluation has been established at the National Geotechnical Experimentation Site (NGES) at Northwestern University. Experimentation at this test section and subsequent analysis and numerical simulation have defined the limits of the ability of the impulse response technique to evaluate damage to drilled shafts in both accessible and inaccessible head conditions.

This project will focus on three main areas, (1) theoretical development of the guided wave approach to consider flexural wave propagation and to consider guided waves in embedded plates, (2) continued development of the prototype system to induce guided and measure guided waves, and (3) continued development of the LWI and SWI methodology.

1. Theoretical developments

We will extend the guided wave theory to look at flexural wave propagation in drilled shafts and piles. We believe that this is important because of the success we have had with the shear wave identification (SWI) test. The theory will allow us to explore the limits of the approach we have developed for shear waves. Application of the developed theory may also allow us to enhance the SWI methodology.

We will extend the guided wave theory to embedded plates so that we can develop techniques applicable to in situ walls, such as structural slurry walls or soil-mixed walls, that comprise part of many excavation support systems. The question of integrity of these wall systems arose a number of times during construction of the Central Artery / Tunnel project in Boston and during construction of the secant pile wall at the Chicago-State Subway Renovation project. During our work on these projects, we found that the conventional techniques based on 1-dimensional wave propagation in a cylindrical structural element were inadequate to provide answers regarding integrity of the as-built walls. We will develop solutions for longitudinal and flexural wave propagation in embedded plates.

2. Continued development of the prototype system to induce guided waves

Conduct laboratory verification tests of the system: We will continue to test the prototype piles in the laboratory in a free condition to develop methods to identify small defects. The defects will consist of a 25 mm saw cut around the perimeter of the cylinder, and a thin discontinuity consisting of a weaker material that extends throughout the cross-section of the pile. We are in the process of simultaneously measuring response with multiple triaxial accelerometers to help identify the mode of vibration.

Trial and optimization of the developed technique for the prototype piles installed at the National Geotechnical Experimentation Site at Northwestern: A major effort in this task is to find better ways to impart high frequency energy into full scale deep foundations. Tests will be conducted at construction sites in Chicago on an ad hoc basis. Case Foundation Company, a leading drilled shaft contractor in the area, will allow us access to newly-constructed shafts during construction.

3. Continued development of the LWI and SWI methodology:

We will continue to develop and test the LWI and SWI methodologies. We will develop real-time data reduction schemes so that reflections can be identified in the field, rather than in a remote location after the data has been collected, as was done for the Port Heuneme project for the Navy. We will conduct additional field tests to verify the methods. We have just finished our second site visit to the Port Heuneme Site for the Department of the Navy, and are currently evaluating the results of these tests. It is expected that these test results will point the way to more improvements with data processing schemes for the LWI and SWI test methods. Additional tests will be conducted at the Sturgeon Bay bridge site and at Port Heuneme.

The work for this project will take place from October 1, 2002 to September 30, 2003. Given the relatively short duration covered by this proposal, all tasks will occur simultaneously.

Given that the weather between March and October should be conducive to field testing locally, the field work at the Northwestern NGES and construction sites in Chicago will take place in these months.

Current Year = $98,167 4-Year Total = $332,459

Two graduate students are working on the project.

Continuation of earlier project

In 1996, 1997 and 1999, the P.I. taught "Foundation Evaluation with NDE Techniques," part of a wider course entitled "Nondestructive Evaluation of Bridge Conditions," for the University of Wisconsin-Madison Department of Engineering Professional Development. He expects to teach the class again in 2001, and will continue to do so as the opportunity arises.

The PI will continue to participate in the User’s Group meetings for the Bridge Project.

Publication of results in journals and conference proceedings also will continue. H.-C. Chou has recently finished his PhD thesis. The following papers describing the guided wave approach and verification of the theory have been published, have been submitted, or will soon be submitted for publication:

Finno, R.J., Chao, H.-C., Gassman, S.L. and Zhou, P., "Non-destructive Evaluation of Drilled Shafts at the Amherst NGES Test Section," Proceedings, International Deep Foundation Congress, ASCE, Orlando, FL., Feb., 2002.

The following article was submitted:

Finno, R.J., Popovics, J.S., Kath, W.L. and Hanifah, A. "Frequency Equation for Cylindrical Piles Embedded in Soil," Research in Nondestructive Testing

The following articles based on the H.-C. Chou’s thesis are being prepared:

Finno, R.J. and Chao, H.-C., "Guided Wave Evaluation of Prototype Concrete Piles," to be submitted to the Journal of Geotechnical and Geoenvironmental Engineering, ASCE.

Chao, H.-C. and Finno, R.J., "A System for Guided Wave Tests on Deep Foundations," to be submitted to the Geotechnical Testing Journal, ASTM.

Chao, H.-C. and Finno, R.J., "Use of the Universal Mode Frequency to Evaluate Shear Wave Velocity in Cylindrical Concrete Members," to be submitted to the Materials Journal, ACI.

Chao, H.-C. and Finno, R.J., "Guided Wave Evaluation of Concrete Cylinders," to be submitted to the Materials Journal, ACI.

A multiple geophone method has been developed which minimizes the effects of the surface wave reflections from intervening pile caps at the NDE test section. The impulse response technique with and without multiple geophone arrays has been used in the field at a number of bridge sites. A theory based on guided waves, describing the relation between frequency and group velocity of frequency-controlled excitations, has been developed to allow higher frequencies to be used to evaluate shafts, and, consequently, to identify smaller defects than possible with conventional techniques. In addition to the guided wave work, we have developed new methods to test piles in the field, termed longitudinal wave identification (LWI) and shear wave identification (SWI) tests, where intervening structure prevents use of impulse response techniques.

Bridge management systems, Infrastructure, Monitoring, Nondestructive testing

A464

Allowable Deformations of Gas Mains Adjacent to Deep Excavations: Phase 2

Richard J. Finno
Northwestern University
847-491-5885
r-finno@northwestern.edu

An advisory board has been established to assure the relevance of the research results. The following people are included in this board.

Dr. Jerry Parola (Case Foundation Company) - Dr. Parola is with Case Foundation, the support system subcontractor for the Lurie Research Center excavation.

Mandoher S. S. Chawla (Department of Transportation, City of Chicago) - Mr. Chawla is the geotechnical engineer responsible for approving all building projects in Chicago.

William Walton (STS Consultants)

Dr. Paul Sabatini (GeoSyntec Consultants)

Dr. Bryan Sweeney (Haley & Aldrich, Boston)

The objectives of this proposed effort are to use the extensive monitoring data from the Lurie Research Center excavation to evaluate the effects of the deformations of gas main pipes and other utilities on the stresses in the pipes, to conduct a comprehensive stress analysis of the gas mains including the connections, and to develop rational methods to define the allowable deformations of such buried pipes when impacted by excavations in urban areas.

Reconstruction in urban areas is ubiquitous. Many deep excavations are made as part of projects that modernize existing urban infrastructure. Because many utilities, including gas mains, are located under the streets, they deform with the ground as the ground adjacent to an excavation moves in response to the attendant stress relief.

Surprisingly, there are no universal guidelines for allowable deformations for buried gas mains or other utilities adjacent to excavations. This lack of standards leads to either ignoring the possibility of damage to gas mains when an excavation is made, or arbitrarily selecting a movement criteria for an excavation project, the purpose of which is to prevent damage to utilities. For example, the City of Chicago requires in some projects that settlements in the street caused by an excavation be limited to 2 inches. This criteria is imposed regardless of the utility being protected, proximity of the utility to an excavation, and the type of pipe being protected. Furthermore, if a gas main were to uniformly settle two inches, no additional stress would be imposed in the pipe. It is distortions that will induce stresses in a pipe that can lead to damage. These distortions arise from both vertical and horizontal movements that are associated with excavations and are not considered in criteria that limit total vertical movements of a gas main.

Northwestern University is constructing the Lurie Research Center on its Chicago campus. As part of the work, a 42 ft deep excavation is planned. As shown in Figure 1, the excavation support system will consist of a PZ27 sheet-pile wall supported by 3 levels of tieback anchors. From the ground surface, the stratigraphy generally consists of 15 ft of rubble fill, 15 ft of medium dense beach sand, 13 ft of soft to medium stiff clay, 40 ft of stiff to very stiff clay overlying hard glacial till, known locally as hardpan. The excavation bottoms out in the soft to medium clay. The water table is located about 15 ft from the ground surface. The upper two tieback anchors are founded in the medium dense sand, and the lower tieback anchor is located in the very stiff clay and hardpan. Also shown in the figure is the location of the utilities in Huron Street. The closest gas main in this section is 28 ft from the edge of the sheet-pile wall. Construction started on April 1, 2002.

Four gas mains bound the excavation site. The stratigraphy generally consists of rubble fill, medium dense beach sand, soft to medium stiff clay, and stiff to very stiff clay overlying hard glacial till. The instrumentation used to monitor the ground deformation includes 149 ground surface survey points, 16 ground anchors, 30 utility settlement anchors, 8 slope inclinometers, and settlement markers in the basement of a hospital adjacent to the site.

The project team has a contract with Facilities Management of Northwestern University to process and interpret the observed deformations associated with the excavation process. We will interpret movements of the ground in relation to the excavation and support system installation and evaluate these movements in light of the contractor’s design predictions. As part of the contract with Facilities Management, we will (1) make independent predictions of movement for various sections of the excavation, (2) visit the site each day, depending on the on-going activities, to detail construction progress in relation to observed movements, (3) process and interpret the performance data, (4) electronically store and plot inclinometer and optical survey data so that the development of the ground movements can be easily seen, (5) adjust predictions of movements based on performance data, and, (6) provide assessments of the progress of the work and the need to adjust construction procedures or support requirements as a function of the observed deformations.

Work Plan for Project: Months 7 through 18

Three main tasks are the focus of this proposed work: continued evaluation of the performance data, stress analysis of the gas main pipes, and parametric studies.

1. Continued evaluation of the performance data from the Lurie Research Center

The excavation is entering a critical stage as far as the amount of ground movements that will develop. As the excavation is lowered through the sands below the second tieback level and into the soft clays, the deformations associated with the excavation will increase. Hence the ground surface and utility movements will also increase. These movements will be recorded, as will the gas main deformations. Given the different distances from the excavation of each main, each line should be subjected to a different set of distortions. While the final deflected shape of the gas main should be quite different as the excavation proceeds. Sharper radii of curvature may develop at the intermediate stages of construction that would represent a more critical loading condition for the gas main. Figures showing these deflected shapes will be developed for each gas main throughout construction. From these deflected shapes, longitudinal bending stresses can be computed.

2. Stress analysis of gas main pipe and connections

The initial stresses in the gas mains arising from soil loads, internal pressures and live loads will be computed using a continuum mechanics approach. The material properties of the pipes will be those of the gas main that are in service at the site, i.e., either cast iron or PVC. The initial stresses form the base upon which the stresses caused by the longitudinal bending from the distorted pipe are added. The stresses in the pipes will be compared to the allowable stresses in the pipes to evaluate the severity of the loading conditions imposed by the excavation-induced movements.

Detailed models of several pipe sections and their joints will be developed. This model will be a finite element simulation in three dimensions, and will include a number of the 12-ft section of cast iron pipe and the bell and spigot joints. The deflected shapes of the soil around the pipe will be imposed in the analyses, and the behavior at the joints will be studied in detail. These studies will supplement the more traditional, continuum-based stress analyses that focus on the response of the gas main pipes.

3. Parametric studies

After the stress analyses of the gas mains at the Lurie Research Center site have been completed, parametric studies will be conducted to extend the range of loading conditions to which those pipes were subjected. The distortions that would cause failure in the pipes will be established on the basis of these analyses.

Further parametric studies using a continuum approach will be made to extend the results of the study to other common materials used as gas main pipe. These materials represent the more modern conveyances, i.e., those materials that likely would be used to replace the older cast iron pipes in place in many parts of urban areas. Since much of the analyses will be three-dimensional, the cost of a computer is included in the budget.

This project runs from October 1, 2002 to September 30, 2003.

The contract for the work was awarded in March 2002. Installation of the sheet-pile walls began in April 2002. According to the contractor, the schedule of the remaining work is:

a. August-October: Excavate to final grade and install second and third levels of bracing

b. November-January (10 weeks): no backfill is placed between temporary and permanent wall

This proposal is for months 7 through 18 of what is planned to be a two-year project. During this period, the field work should be completed if the contractor adheres to the schedule, the stress analyses of the gas mains finished, and the parametric studies should be started.

Current Year = $75,073 4-Year Total = $144,188

Graduate students: Kristin Molnar, an MS student specializing in structural engineering, will work on the project this budget period and will focus on the analyses of the gas mains and the parametric studies. Other students funded from different sources are also working on this project, including Jill Roboski, a PhD student, is responsible for the evaluation of the field data, Michele Calvello is finishing up his PhD and is focusing on the finite element studies, especially the automatic updating of parameters based on observed field responses, Terence Holman, a PhD student, who is working on defining the small strain behavior of the compressible glacial clays. These students will interact with Molnar on the gas main aspects of the work.

This is the second phase of a proposed two-year project.

We propose to present our results to an advisory board consisting of practicing engineers, contractors and owner’s representatives to provide review for the results of the research and to assure that the results are relevant to engineering practice. This board has been formed as part of the PI’s National Science Foundation grant entitled "Objective updating of design predictions for supported excavations using construction monitoring data." This board will meet in the beginning of October, and the results of this work will be presented to them as part of the annual meeting.

The principal investigator will present the results of the study to professional societies both locally and nationally. Papers will be submitted to journals and future conferences to further disseminate the findings.

There are no universal guidelines for allowable deformations for buried pipes adjacent to supported excavations. The excavation for the Lurie Research Center represents a unique opportunity to develop much needed field performance data to evaluate the effects of excavation-induced ground movements on the in situ behavior of gas mains. When coupled with a detailed stress analysis of the gas main pipes, this data can be used to define safe limits of excavation-induced movements. The stress analyses will allow one to use the detailed field observations as a basis for more general recommendations.

Deformation, Excavation, Gas utilities, Infrastructure

A465

Commercialization of TDR Measurement of Soil Deformation in Support of ITI Thrust Area for Remote Monitoring for Bridge Management

Charles Dowding
Northwestern University
847-491-4338
c-dowding@northwestern.edu

OhioDOT Installation of TDR cables beneath I 70 near Cambridge

George Beiter
District 5 Planning and Programming
P.O. Box 306
Jacksontown, OH 43030
(740) 323-5192
George.Beiter@dot.state.oh.us

INDOT Installation of TDR cables in deforming abutment of Rt 62 & I 64 bridges

Dan Chase
Division of Materials and Tests
120 S Short Ridge Rd.
Indianapolis, IN 46219
(317) 232-5280 ext 229
DCHASE@indot.state.in.us

PennDOT Installation of TDR cables and tiltmeters along subsiding portion of I 70

David Whitlach
District Geotechnical Engineer Dist 12-0
Department of Transportation
Commonwealth of Pennsylvania
P.O Box 459
Uniontown, PA 15401
(274) 439-7357

Fl DOT/PSI Installation of TDR/tiltmeter system to monitor sinkhole deformation

John Barker
District Materials Engineer Dist 6(?)
Bartaw, FL
1-800-292-3368
john.barker@dot.state.fl.us

Ching Kuo
PSI
5801 Benjamin Dr
Tampa, FL
(813) 886-1075

CALTRANS Qualification of TDR cable for remote detection of concrete failure

Allan Chow
Toll Bridge Investigations
Structure Maintenance & Investigations
P.O. Box 23660
Oakland, CA
(510) 286-1361

WYDOT Satellite communication for surveillance of remote facilities

John Turner, Professor
Department of Civil Engineering
Wyoming University
Laramie, WY
turner@uwyo.edu

Field measurement of TDR cable sensitivity in soft soils can be accomplished by installation and monitoring of the response of unique field sites. Continued potential of misapplication of the technology also points out the need for positive case studies that demonstrate the importance of the use of appropriately compliant cables.

Time Domain Reflectrometry (TDR) techniques replace other manual methods for assessing lateral movement of bridge abutments and piers. TDR’s remote operability and its inherently digital nature provide an appropriate and remotely operable method for monitoring stability of critical bridges while they await repair. Occurrence of excessive bridge pier and abutment movement is large. For instance scour induced deformation was responsible for some 40 bridge failures during the Mississippi and Missouri flooding of 1993.

Compliant cable-grout composites are necessary to maximize the use of TDR technology in soft soils. To date, TDR cables have been extensively deployed in rock and stiff soils. Recently, stiff, commercial cables installed with weak grout have been deformed with movements of 0.01 m (0.5 in) in soft lake clays. This observation has caused a shift in development emphasis from the cable itself to the reaction of the grouted hole-cable composite

It is important to further develop these special cable-grout composites for soft soils as State DOT’s are beginning to experiment independently and will require assistance to ensure that the technology is evaluated properly. Furthermore, exploratory field work with State DOT’s has revealed an overly simplistic view of installation requirements, which makes publicity of the importance of the composite view all the more critical.

Successful monitoring of mine-induced subsidence of I 70 with TDR-Tiltmeter technology for Pennsylvania DOT has led to use of this combination of instruments for surveillance of sinkhole subsidence of SR 66 and US 27 in Florida this last year.

This next year will be employed to complete field testing of ITI-developed compliant cable at the Lurie excavation in Chicago, and bring SR 66 and the Klamath River bridges on line for autonomous, real-time display of data for these two unique sites. SR 66 instrumentation for FDOT is unique because it monitors a sink hole with a horizontal cable. The Klamath river bridge for CALTRANS is unique because it involves TDR measurement of water level, which is important for scour surveillance. The Klamath site is also important because CALTRANS is the first DOT to be approached to purchase programs and/or services of the ITI incubated Application Service Provider company.

Task 1: Field Test of Flexible Cable Developed by ITI

Monitoring of potential deformation of gas transmission lines adjacent to the Lurie excavation in Chicago presented an opportunity to field test the new flexible cable developed by ITI. Deformations associated with the deep excavation are being measured by slope inclinometers, pipe deflectometers, and a large number of settlement points. These measurements provide the comparisons with TDR readings that are necessary to commercialize the TDR approach. Two cables were installed this Spring with soft grouts to optimized for soft soils: one with a stiff, solid aluminum outer conductor, and the other with a flexible braided outer conductor. Grouts were specifically designed for each to maximize their response in the softer soils. The excavation is expected to be completed this Fall and the results will be presented in a thesis that documents installation procedures for all of the ITI sponsored TDR installations. The science behind the optimization of cable/grout vs. soil stiffness is supported by previously conducted interpretation of cable-grout composite sensitivity with finite element modeling.

Task 2: Ensure Autonomous Operation of Advanced TDR Installations w/ CALTRANS and FlDOT

While first generation TDR installations with OhioDOT and InDOT are operating autonomously, the most sophisticated and unique installations are not. These installations are the CALTRANS Horse Creek Bridge over the Klamath River and the FlDOT State Road 66 sink hole land bridge which incorporate TDR water level sensors, tilt meters and a unique horizontal TDR cable (FlDOT). Operation of the Horse Creek installation is critical because CALTRANS has been identified as the ‘beta" client for the server side ASP project (See ACM proposal). The SR 66 installation is critical because it incorporates a unique horizontal TDR cable that allows surveillance of a spatially large volume. State personnel at both sites are actively concerned about the operability of the systems.

Horse Creek can be rendered autonomous by reconfiguring the system with Campbell Scientific data loggers and Applied Geomechanics tiltmeters. The reinstallation will be made with both GeoTDR and Dan Marron so that Marron can be trained on the details of the Campbell instrumentation.

State Rd. 66 is more challenging because it is neither powered nor connected by a land-line phone system. It appears that resuscitation will require switching pulsers, installation of a larger solar panel and installation of another cell phone modem. While these tasks are being undertaken by FlDOT technicians, another trip will be required by GeoTDR.

Task 3: Add Satellite Communication and Solar/Propane Power System to WYDOT Installation

An EDC team has identified the least cost combination of satellite Internet Service Provider and propane power systems for remote installations such as several identified in Wyoming. The two candidate sites are near Tetons National Park and Devils Tower. ITI will supply the Satellite communication and power modules as a demonstration of this alternative method of communication from remote sites. Installation will be accomplished within the next Federal fiscal year as WYDOT plans are underway for installation of TDR deformation and water level sensing cables at these two sites.

October 1, 2002 to September 30, 2003

1. Field Test Flexible Cable: Fall and Winter

2. Ensure Autonomous Operation of CALTRANS and FlDOT sites: Fall through Spring

3. Add Satellite Communicatin to WyDOT site: Fall through Summer

Current Year = $99,102 4-Year Total = $378,894

Graduate Students: Tanner Blackburn, recipient of the 2001-2002 ITI fellowship, is finishing his thesis, ITI Specialty TDR Cable and 3D TDR Analysis. Matt Dussud has begun his MS thesis on a history of and workbook for TDR installations.

Undergraduates: Work of Dave Kosnik and Mat Kotowsky have direct application to TDR as well as ACM web presentation. Their work has led to the automation of TDR sites for Ohio and Indiana DOT’s. They have been working with the ITI/ACM/TDR team to develop Java server side programs that are critical to the success of the automation project. Dave and Matt are seniors at Northwestern and University of Illinois respectively.

Continuation of Geotech/TDR component of Condition Monitoring Thrust

The TDR 2001 Symposium, held in September of 2001 allowed extensive interaction with the scientific and consulting portions of the user group. The one hundred or so participants, many from near-by state DOT’s, participated in short courses, standards discussions, and equipment demonstrations as well as listening to the symposium speakers.

TDR research will continue its interaction with the Bridge NDE User's Group to ensure thorough integration with ITI and State DOT activities. Details of the activities of this group are described in the proposal submitted by David Prine on behalf of the ITI Remote Bridge Monitoring group. For instance a special Internet-based televideo conference on scour with OhioDOT was conducted in the Spring of 2001.

Documentation of field measurements of comparable TDR and slope inclinometer response at the demonstration sites is critical for gaining market acceptance. Use of TDR in high profile situations like that of the I 70 and I77 subsidence and FlDOT sinkhole monitoring will also assist in this regard. Publicizing these endeavors will be pursued through a series of ever increasingly wide distribution channels. The I70 instrumentation project was published this year in the Transportation Research Record and was short listed as an important paper of practical significance. This paper generated an entire session on TDR monitoring at the January 2001 TRB.

The compliant cable can be licensed to GeoTDR for installation after exploration of other alternative distribution channels. A provisional patent application could be filed to ensure that any intellectual property is held during exploration of alternative licensees. Such filing allows one year before a full patent application must be made.

Success of marketing with GeoTDR is evident with several of our installations. GeoTDR relationships were key to the installations in conjunction with OhioDOT, LTV (Clark), PennDOT, IDOT, (rock causeway) and in 2001, FlDOT. Given this past record of symbiotic success, There is every reason to believe that GeoTDR's marketing efforts will support the commercialization of compliant TDR cable.

TDR specific user community involvement was fostered through five mechanisms: papers at workshops and specialty sessions, demonstration projects, TDR-L Email listserve, the TDR 2001 Symposium, and installations and consulting by Dr. O'Connor of Geo TDR.

Publications and presentations include:

"Real-Time Monitoring of Subsidence along I-70 in Washington, PA" (w/ O’Connor, K.M. and PennDOT personnel) TRB meeting January 2001. This paper was highlighted in catalog of practical papers of immediate value to transportation engineers

"Time Domain Reflectometry for Landslide Surveillance" Landslides:Causes, Impacts, and Countermeasures, H.H. Einstein et al Eds. United Engineering Foundation, NY, NY, pp 249-260, June 2001

"TDR 2001: The Second International Symposium and Workshop on Time Domian Reflectometry for Innovative Applications, Northwestern University, Infrastructure Technology Institute, http://www.iti.northwestern.edu/TDR, 400pps

"Three Dimensional Finite Element Analysis for Design of TDR Cable Grout Composite in Soft Soil". Paper submitted in May 2002 for review in the Journal of Geotechnical and Geoenvironmental Engineering of ASCE.

"GeoMeasurements with Metallic TDR Cable Technology for Infrastructure Surveillance" (Paper No. 02-2562). Paper presented at the Annual TRB Meeting, January 2002.

"Measurement of Localized Soil Deformation with Time Domain Reflectometry" by Pierce, C.E. and Dowding, C.H. Accepted for publication in the Journal of Geotechnical and Geoenvironmental Engineering of ASCE in May 2002.

The TDR listserve, operated by ITI, continues to serve some 150 to 200 TDR suppliers and consumers. Provision of this communication channel maintains ITI's preeminence in TDR technology. Details can be found at

http://www.iti.northwestern.edu/tdr/index.html

Indirect support of Dr. O'Connor's efforts to build GeoTDR, a company that specializes in TDR instrumentation, has been instrumental in developing ITI sponsored demonstration projects. For instance, GeoTDR installed the cables for the PennDOT and FlDOT projects. Without his assistance, PennDOT would not have been able to develop their alarm system.

Organize and host the International TDR Symposia, the most recent of which was held in the Fall of 2001.

In addition to bridge monitoring, development of a TDR system to detect deformation in soil will allow further understanding of the localized shearing. Heretofore, deformation could only be measured with a resolution of 60 cm with slope indicators. When fully developed TDR technology will allow a resolution of 2 to 5 mm, which is a 100-fold increase in resolution.

Time domain reflectometers, Deformation, Soft soil, Bridge management systems, Monitoring, Monitoring systems, Infrastructure

A466

Introducing Size Effect Into Design Practice and Codes for Concrete Infrastructure

Zdenek P. Bazant
Northwestern University
847-491-4025
z-bazant@northwestern.edu

The overall objectives of the project are:

1. Capitalizing on two decades of basic research funding of the principal investigator (PI)’s research of size effect at Northwestern University, demonstrate practical applications to design and testing.
2. Based on the general theory already developed, construct simple design formulae for the size effect in various basic type of failure, suitable for use in design firms.
3. Work in engineering societies, particularly ACI, RILEM and FIB (generally co-opted by AASHTO), to introduce changes in the respective code articles, one by one, beginning with the diagonal shear failure of reinforced concrete and with the flexural failure of plain concrete.
4. Formulate a statistically correct structure of load factors for the code, suitable for use after the size effect is taken into account in code provisions.
5. Formulate test procedures for concrete strength and fracture taking the size effect into account, and propose improved testing standards to ASTM and RILEM.
6. Translate existing material models for quasibrittle fracture, capable of capturing the size effect, into subroutines suitable for use in computer codes in design, including commercial codes.
7. Articulate the reasons and promulgate the necessary changes by tutorial presentations at conferences.

This is the second phase a proposed three and one-half year project that will focus on the introduction of size effect, and along with it fracture mechanics background, into 1) design practice, 2) design codes, 3) standardized materials testing, and 4) commercial computer programs for concrete structures. This is important not only for large-span pre-stressed concrete box bridge girders and box girders of cable-stayed bridges, but also for the supporting piers and foundation plinths, as well as for road and airport pavements, earth-retaining walls, tunnel linings and dams (which often carry highways).

The design practices for ductile failures are not affected, but those guarding against brittle failures, which currently still are based on the plasticity-based theory of limit states, need to be updated for size effect according to fracture mechanics and random strength statistics. ASTM and most other material testing organizations do not yet have a standard test for concrete fracture, and especially have none conforming to the size effect theory. The commercial computer programs are generally not based on fracture mechanics and do not consider the size effect.

The basic theory (summarized in the principal investigator’s two recent books) is now ripe for practical application. However, simple design formulas for particular design problems need to be developed and proper material testing procedures instituted. Moreover, clear and convincing articulation for the need for updates to codes will need to be made to the relevant committees of ACI, RILEM and FIB (specifications of which are followed by AASHTO).

Major tasks for this twelve-month period are:

1. As member (and former founding chairman) of ACI Committee 446, Fracture of Concrete, argue for a sound method for the fracture energy test (a sound one from the size effect viewpoint) aiming at a recommendation from this committee to ASTM. Prepare a statistical study justifying the proposed testing method and evaluation procedure and submit it for the committee report in preparation.
2. As chairman of the RILEM Committee QFS, Quasibrittle Fracture Scaling, work on the state of art report and incorporate in it sound recommendations on the size effect in reinforced and plain concrete structures, based on the theoretical researches previously carried out at Northwestern.
3. Join the subcommittee on strength testing of ASTM Committee C-04 (Concrete) and argue for the proposed new modulus of rupture test updated for size effect. Prepare and submit an improved formulation of the standard.
4. Join of ACI Committee 447, Shear and Torsion, and prepare a proposal for an improved design formula for designing against the diagonal shear failure of beams, and articulate the reasons for it.
5. Present papers at international conferences on bridge management and maintenance (initiated in 2002 by D. Frangopol) to argue the need of revising the structure of load factors for bridges, particularly the load factor for self weight, and to introduce the size effect.
6. Initiate a statistical study aimed at rational prediction of failure loads of an extremely small failure probability, which would agree with extreme value statistics and could conceivably replace the empirical load factors current used in the design codes for buildings and bridges.
7. Clarify in papers and conference presentations the requirements for confining reinforcement of concrete columns (tied, spiral and tubular, including bridge columns) needed to suppress or minimize the strain-softening response of concrete and thus to suppress or minimize the size effect.
8. As chairman of the NSF International Workshop on Durability (Prague 2002), prepare and publish in ASCE a special issue based on Workshop papers featuring, among others, the problems of durability of bridges (often impaired by fracturing).
9. As member of the US National Committee on Theoretical and Applied Mechanics, collaborate on the Committee’s goal of finding ways to improve the transfer of theoretical results into practice (currently the main topic on the agenda).

October 1, 2002 to September 30, 2003

Current Year = $66,766 4-Year Total = $127,154

Postdoctoral fellow: Dr. D. Novak

Graduate Research Assistant: G. S. Pang

This is a continuation, following the first six months, of a proposed three and one-half year project.

Much of the focus of this project is on technology transfer through advancing updates to codes, advancement of new design and testing methods, and presentations at conferences. The PI will be active in the relevant committees of ASTM, ACI and RILEM. Activities include promoting new and updated codes, design recommendations and testing methods as part of the ASTM Committee C-04 (Concrete) and subcommittee on strength testing; ACI Committee 447 (Shear and Torsion); ACI Committee 446 (Fracture of Concrete); RILEM Committee QFS (Quasibrittle Fracture Scaling). Additional transfer activities include: presenting papers at international conferences on bridge management and maintenance; prepare and publish in ASCE a special issue based on the NSF International Workshop on Durability (Prague 2002) featuring, among others, the problems of durability of bridges; and collaborate with members of the US National Committee on Theoretical and Applied Mechanics to find ways to improve the transfer of theoretical results into practice.

According to the classical theories of failure such as elasticity with a strength limit of plastic limit analysis, a structure fails when the maximum stress reaches a certain critical value that is independent of structure size. This simple concept is valid for many situations, for example the bending failure of a steel girder or the failure of tensile reinforcement in a reinforced concrete beam. In modern concrete structures, however, there are many situations where this simple concept breaks down and the apparent material strength (or nominal strength) decreases with increasing structure size. This is called the size effect.

There are two physical causes of size effect: 1) the statistical cause, consisting in the randomness of material strength; and 2) the deterministic cause, consisting in the release of strain energy stored in the structure into the front of a propagating crack.

The basic theory of the statistical size effect, formulated by Weibull in 1939, was universally believed to be the only explanation of the size effects observed experimentally in concrete structures until the 1980s. The belief is no longer universal. A theory is now generally accepted by the leading researchers that deterministic size effect exists and is in fact dominant for all quasibrittle materials, not only concrete, but also rocks, ice, tough ceramics and fiber composites. However, the theory has not yet penetrated general concrete practice, design codes, materials testing, or the commercial computer programs for structural design.

The basic theory of the deterministic size effect was developed largely at Northwestern by the PI, under a series of grants from NSF, AFOSR and ONR. It was presented in a recent textbook (Bazant and J. Planas, Fracture and Size Effect, CRC Press, Boca Raton 1998), and the advanced aspects in a monograph just published (Bazant, Size Effect on Structural Strength, Hermes-Penton, London 2002). The present project is aimed at bringing this new theory into practice.

Concrete, Infrastructure, Fracture mechanics, Design standards

A467

Commercialization of Instrument for Micro-Inch Measurement of Crack Width in Support of Thrust in Remote Monitoring for Bridge Management (continuation of Triggered, Real Time Display of Infrastructure Response)

Charles Dowding
Northwestern University
847-491-4338
c-dowding@northwestern.edu

Chuck Howe
Geotechnical Engineering Section
Materials & Research Laboratory
MNDOT
1400 Gervais Avenue
Maplewood, MN 55109
612-779-5602

Darren Pleiman (City of Las Vegas project)
Kleinfelder Engineers
6380 Soputh Polaris Ave
Las Vegas, NV
702-736-2936 ext 107
dpleiman@kleinfelder.com

Gary Johnson
Regional Transportation Authority
Clark County Nevada (Las Vegas Project)
702-676-1500

Prof. Catherine Aimone (State regulatory project & NMDOT project)
New Mexico Institute of Technology
Soccoro, NM, 87801
505-835-5346
caimone@mailhost.nmt.edu

Alvin Budd
Vice President of Adminstration
GeoSonics
PO Box 779
Warrendale, PA 15095
724-934-2900

Larry Corneius
President, LARCOR
OEM White Seismographs
Quinlan, TX
903-356-2338

Ron Mask
Sales Manager
OEM Instantel
Kanata, Ont., Canada
613-592-4642

There are two main divisions of this project: 1) autonomous measurement of micro-inch vibratory and long-term crack movement and 2) autonomous graphical display of the results via the Internet. Its successes in 2) autonomous graphical display compliment and support other ITI Bridge Monitoring projects. For instance, instrumentation of the Sturgeon Bay Bridge is built around the concept of Internet display with the server software developed through this project. With regard to micro-inch sensing, the ultimate goal is to cooperatively develop with GeoSonics and other manufacturers of vibration instruments a remotely operable and accessible instrument to measure micro-inch changes in crack width.

Public concern over construction and traffic vibration-induced CRACKING has led to the search for a radically new approach to vibration control. This project to develop Autonomous Crack Monitoring (ACM) equipment and software for real-time monitoring and internet display of crack response and weather supports development of such a new approach to monitor and control construction induced vibration. The new instrument will automatically record and allow comparison with long-term changes in crack width as well as those produced by ground motion. Internet based, real-time public access to these data is fundamental to this new approach.

Measurement of micro-inch changes in crack width from environmental and vibratory effects provides information in a visual form that can be understood by lay bodies and regulatory administrators who control vibration limits, which ultimately control construction of transportation facilities. The present approach of correlating time histories of ground motion and past observations of cracking is simply too difficult for most jurors and village and county regulatory boards to understand. Use of such a system will allow an understanding of relationships between vibratory and environmental effects not now possible and potentially may avoid payment of 10's of millions of dollars in claims and construction delays each year. Successful installation of ACM instruments for the Clark Co. RTA (Las Vegas) to monitor building response to construction vibrations generated by road widening underscores the value of this approach.

A joint project has been developed with the City of Las Vegas, Clark County RTA and Kleinfelder to assess the relative vibratory effect of construction equipment during widening of one of an arterial roadway. Vibratory crack response to motions produced by vibratory rollers and a large back hoe excavating caliche (a rock-like material formed by cemented sand-gravel-cobbles) will be evaluated. Effects of vibratory rollers have become the object of a sufficient number of complaints that the City wished to quantify the issue. The city has purchased a house for ACM instrumentation that is contiguous to the right of way. This project began the Summer of 2002 and should be completed by the end of the Fall.

After data are gathered, a thesis and an article for TRB will be written and an archived prototype ACM site will be produced for construction equipment vibrations. This site will be helpful in future efforts to encourage adoption of this technology with DOT’s in urban areas where typical construction produced vibrations that can become an issue of contention.

This project will be combined with the ongoing Connecticut project and a new project with the New Mexico DOT. These unique opportunities will allow further integration of White Seismographs and Somat technology. Should this combination continue to prove easy to install, it may provide an alternative path to commercialization of the ACM approach to vibration monitoring.

A roadway aggregate producer in Connecticut has provided a house and is funding Aimone & Assoc. for the collection of house response and crack data while the blasting techniques are varied widely. This project will end in the late Fall and results will be incorporated into a thesis.

The New Mexico DOT has hired Aimone & Assoc. to instrument structures along a highway realignment through Riodoso New Mexico. One of the structures of concern is a built into the side of a rock out crop and provides a unique opportunity to adapt ACM technology for monitoring the response of critical natural geologic structures to construction vibrations.

This is the last year before Dave Kosnik graduates, and it is important that his significant developments be documented so that other NU EE’s can be recruited to operate the system. To ensure that the polling/serving code can be simultaneously finalized and documented it has been decided to commercialize the code by incubating Kosnik and Kotowski into an Application Service Provider. ITI will be the "alpha" customer and CALTRANS will be the "beta" customer. B. Johnson of the Illinois Technology Enterprise Corporation has agreed to assist in this process.

Discussions with the three main OEM’s of vibration monitors: Geosonics, White Instruments, and Instantel will be undertaken to assist them in development of ACM capable instruments that are independent of Somat equipment. As part of the development process these products will be affixed to the Milwaukee test house and reported data will be compared to that produced by ITI-Somat prototypes.

As a first step in this process, Geosonics has promised to ship one of its prototypes this Fall. This is the Phase III step in the codevelopment process outlined in earlier project reports.

The other manufacturers will be visited to help write system specifications for development of their equipment to ensure the ability to monitor both long term and short term crack response.

October 1, 2002 – September 30, 2003

1. Assess Construction Vibration Impact (Las Vegas)

2. Integration of ACM with White Seismograph in NMDOT project

3. Launch Application Service Provider

4. Develop Milwaukee as Test Bed for Instrumentation

Current Year = $101,576 4-Year Total = $360,400

Graduate Students

· Laureen McKenna and Micky Snider documented: 1) atypical structure response, 2) qualification testing of specialty sensors, 3) Las Vegas construction vibrations project, 4) Connecticut aggregate quarry blast design study

· McKenna’s MS Thesis was published in April of 2002; Snider’s in 2003.

· Laureen McKenna was the 2001 recipient of the ITI Student of the Year Award"

Undergraduate Students

· Dave Kosnik, Junior at Northwestern University. Has been working with the ITI/ACM team since the summer before his Freshman year to develop Java server side programs that are critical to the success of this project.

· Matt Kotowsky, Junior at the University of Illinois has joined the team to speed the development of server side programs.

· Ker Min Chok, also a Northwestern Junior, assisted on various data reduction projects and ITI publication of book, Geotechnical Materials: Measurement and Analysis.

Continuation of "Triggered, Real Time Display of Infrastructure Response"

Industrial and regulatory interest in this concept is strong. Formal coordination of parallel co-deployment efforts with GeoSonics, a world leader in the manufacture of vibration monitoring instrumentation, demonstrates the potential for its immediate application. For instance, a beta test model for on site polling has already been deployed by GeoSonics for one of their clients. Vulcan Materials Corp. has loaned ITI the use of a home (adjacent to one of its quarries) for use in the development of the ACM system. This year the ACM on site polling equipment has been integrated with White Industrial Seismographs in a nation-wide study of the response of atypical structures sponsored by State regulatory agencies. Next year both Instantel and White Seismographs will both begin to develop ACM capable instrumentation.

It is anticipated that this project will continue significant interaction with the ITI Bridge NDE Users Group to ensure thorough integration with ITI and State DOT activities. Details of the activities of this group are described in the proposal submitted by David Prine on behalf of the ITI Remote Bridge Monitoring group. This coming year the User's Group will meet several times as a continuation of the tradition of holding both regional and national meetings. This group will be briefed on the results of the Las Vegas project.

In addition a, specific user group in the field of construction vibrations has been developed. This group is connected via the Constvib listserv that is accessed through the ACM web site: http://www.iti.northwestern.edu/acm/. This group is some 300 large and from time to time exchange messages concerning vibration issues of mutual interest.

The vibratory roller project with Las Vegas is an example of the usefulness of the Constvib listserve. At the same time Las Vegas was expressing and interest, there was unusually high Email traffic on the listserv about vibratory roller excitation. This traffic closed the circle of interest about the issue and helped focus the research and project.

Presentations were made at several locations to assess reaction to this thrust. In January 2002 a presentation entitled "A Radical New Approach to Vibration Monitoring and Control" was made at the 4rd Biennial Blasting Vibration Technology Conference, in Key West FL (which is sponsored by Geosonics). In December 2001 the Mueser Rutledge lecture was given in New York City on the topic of "Monitoring and Control of Construction Vibrations".

In a serendipitous series of events, the PI has been elected to the Board of Directors of the International Society of Explosive Engineers. This office will allow an expanded degree of interaction with the community of vibration instrument manufacturers not heretofore possible.

Commercialization of micro-inch crack measurement technology (ACM) is being conducted by advertisement through the following channels: (1) technical journal articles, (2) instrumentation, vibration, civil, geological, explosives, quarrying, mining, and construction magazines, (3) direct marketing to operators through the co-deployment associate, Geosonics, (4) Northwestern University www sites, and (5) short courses and seminars. As described above, all five of these channels are being pursued.

In addition, as described above