Implications of the Global Surface Fault Distribution and of Lithospheric Cooling

This contribution presents a model that links the observed distribution of surface faults to the spatial distribution of marsquakes. The annual seismic moment budget is computed based on the as-sumption that global cooling and subsequent shrink-ing of Mars is the main source of strain today [1]. A truncated Gutenberg-Richter distribution is used to re-late the seismic moment budget to marsquake frequen-cies. We have derived a theoretical relation for the limitation of quake size by the lengths of the individual faults. This relation is used for the simulation of epi-center catalogs that may serve as input data for the development of seismological experiments

The Removal of Lead-Based Paint from Steel Bridges

The purpose of this study was to assist the Department of Highways in conducting bridge-painting operations involving removal of existing lead-based paint. Pertinent state and Federal regulations affecting generation of hazardous wastes, limiting environmental pollution and protecting public and worker safety were obtained and reviewed.State highway agendas were surveyed relative to how they conducted maintenance bridge painting involving lead-based. paints and comply with applicable regulations. Information from the painting industry related to sale removal of lead-based paints was also reviewed. Based upon the reviews of applicable regulations, operations of other state highway agencies and painting industry practices, the best demonstrated available technology to use in removing lead-based paints from bridges was identified. The key technologies incorporated the use of: 1) containment enclosures over the open abrasive blasting, 2) recyclable abrasives and 3) closed material-handling systems to move abrasive-blasting wastes. The Study Advisory Committee determined that the Best Demonstrated Available Technology would be applied to all bridge maintenance painting operations involving the full removal of lead-based paints. The Committee decided that the Department of Highways would limit painting contractors\u27 work to painting-related activities. The Department employ a consultant to monitor activities related to the generation of hazardous wastes. The consultant would also inspect the contractor\u27s painting work. The Department would also employ a contractor to transport treat and dispose hazardous wastes generated by abrasive blasting. Three documents were prepared to facilitate this work including: 1) an experimental special provision for bridge maintenance painting, 2) a invitation-to-bid for hazardous waste transport and disposal, and 3) a consultant services contract for environmental monitoring, waste management and inspection of contractor painting operations

Survey of the Impacts of Environmental Regulations on State Highway Operations

In recent years, the transportation industry in Kentucky as represented by Kentuckians for Better Transportation (KBT) and the Kentucky Transportation Cabinet (KyTC), have expressed concern over the growing impact of environmental regulations upon transportation activities in the state. The imposition of environmental regulations has resulted in higher costs for new construction and maintenance on roads, project delays, scheduling and financing difficulties, and the creation of additional transportation agency bureaucracy to address environmental regulation mandates. In Kentucky, the impacts of those regulations have not been thoroughly assessed nor have the attendant costs been measured. Coinciding with that lack of information is the concern whether those impacts (e.g. costs and delays) are comparable with those affecting other state transportation agencies. KBT and KyTC contracted with the Kentucky Transportation Center (KTC) to conduct a study to 1) identify the impacts of environmental laws and regulations on KyTC and 2) determine whether the environmental impacts affecting KyTC are comparable to those affecting other state transportation agencies

Stress Measurements on the I 65 Bridge over the Ohio River at Louisville

Kentucky Transportation Center personnel conducted measurements of live stresses on structural members of the I 65 (John F. Kennedy Memorial) Bridge over the Ohio River. That work was performed in conjunction with an extensive flaw evaluation of the bridge by Hazelet & Erdal Consulting Engineers. The measurements were performed by placing strain gages on the upper chord (an H-beam) and a vertical post and transverse strut that were framed into the upper chord at PP63 on the West truss. Measurements were performed using battery-powered data logging instruments that were capable of unattended strain measurement. The units were used to monitor live stresses induced by routine traffic. Specific tests included short duration time-history measurements on the three structural members, a short duration strain gage rosette measurement on the upper chord and a day-long stress histogram measurement also on the upper chord. The time-history measurements were intended to measure the magnitude of live stresses in the beams. Multiple gages were installed on opposite faces of the structural members for those tests to gain insight into the nature of forces acting on them. The rosette test was performed to measure the principle stresses acting on the upper chord and, thereby, ascertain the nature of forces acting on the upper chord. The stress histogram measurements were conducted to determine the magnitudes of live stresses and number of stress cycles over an extended period. The time-history test data revealed low magnitude live stresses at all the test locations. The maximum tensile live stresses measured were: 1) 1,147 psi for the upper chord, 2) 2,230 psi for the vertical post and 3) 580 psi for the transverse strut. The rosette test yielded a maximum principle stress of 1,120 psi. The stress histogram data indicated that the variable-amplitude live stresses acting on the bridge were comparable to a constant-amplitude live stress of 1,660 psi at a rate of 773,864 cycles per year. Comparisons of stress data taken on the upper chord indicated that it was subject to some non-axial forces. Similar measurements taken on the vertical post indicate that it was subject to transverse forces possibly induced by the strut. Based upon the low stress magnitudes measured during the tests, it appears that live stresses generated by traffic do not have a significant impact on the structural integrity of the bridge

Survey of Current Bridge Painting Practices and Related Literature Search

A survey on current bridge painting practices was conducted. Questionnaires were sent to all 50 state highway agencies concerning their present bridge painting practices, changes in those practices that they anticipate due to environmental regulations, and new or experimental painting practices they are investigating. Forty-three responses were received. Those are collated and presented in the appendices along with comments of the responders. A literature search was conducted on publications related to painting of steel structures (since 1987). Forty-nine documents were identified as being relevant to the topic. Those documents are listed in bibliographic form in the appendices

Environmentally Safe Protective Coatings for Steel Structures-New Construction and Maintenance Painting

The purpose of this study was to: 1) assist KyTC in identifying protective coatings lor structural steel that would meet current and pending environmental regulations, I and 2) to evaluate overcoating procedures that would be cost-effective and provide regulatory (OSHA and EPA) compliance. A coatings research program was conducted that included: 1) laboratory accelerated corrosion/weathering tests, 2) field exposure tests, and 3) experimental maintenance I painting of entire bridges by overcoating. Each of those tasks was intended to address different issues. Regulations concerning volatile organic compound limits lor coating systems used in new construction were studied and recommendations provided to KyTC on new systems that would provide potential advantages in application I and performance. The laboratory testing was used to evaluate seven candidate overcoating systems and three new construction coatings systems. Field exposure tests consisted of coatings patches applied to bridges and scrap steel. Those tests provided useful information concerning the durability of candidate maintenance coatings and the practicality of experimental application procedures. Eighteen complete bridge maintenance painting projects were conducted the KyTC experimental overcoating program that employed experimental specifications and coatings system. Those projects were inspected prior to, during and subsequent to completion. Long-term performance of most projects has been very good

Explanatory debugging: Supporting end-user debugging of machine-learned programs

Many machine-learning algorithms learn rules of behavior from individual end users, such as task-oriented desktop organizers and handwriting recognizers. These rules form a “program” that tells the computer what to do when future inputs arrive. Little research has explored how an end user can debug these programs when they make mistakes. We present our progress toward enabling end users to debug these learned programs via a Natural Programming methodology. We began with a formative study exploring how users reason about and correct a text-classification program. From the results, we derived and prototyped a concept based on “explanatory debugging”, then empirically evaluated it. Our results contribute methods for exposing a learned program's logic to end users and for eliciting user corrections to improve the program's predictions

Stress Evaluation of Welded Steel Bridges on Coal-Haul Routes

This report describes the procedure developed and being employed to determine and assess live-load stresses in structural members of welded steel bridges on extended· weight coal haul routes. Those bridges are routinely subjected to loads from coal trucks in excess of those permitted on other routes. Those elevated loads may result in high stresses in bridge members. Of principal concern are certain weld details on steel bridges that are susceptible to fatigue cracking when subject to high live-load stresses. Seventeen welded steel bridges on extended-weight coal haul routes have been identified for investigation under this study. The study test procedure consists of 1) a review of coal-haul data and plans to identify lanes of a bridge subject to greatest coal-truck loading, 2) identification of weld details of interest for analysis on portions of the bridge superstructure subject to high live-load stresses, 3) field application of strain gages to measure live-load stresses at locations of interest on a bridge, 4) continuous monitoring of live stresses from routine traffic for an extended period and 5) data retrieval and reduction and fatigue analysis. Fatigue analysis is based on the number of stress cycles measured during the field test and the equivalent resolved live-load stress. That is compared to the 1992 AASHTO fatigue performance data for applicable structural details (e.g. welded connections). An exemplary use of the study test procedure is given for the KY 15 bridge over the North Fork of the Kentucky River and KY SO in Perry Co. This report describes the test locations, test procedures and results of the derived test data. The field tests will indicate the level of live-load stresses to which the bridges are exposed. Additionally, the fatigue analyses may indicate whether welded steel bridges on extended-weight coal haul routes are susceptible to fatigue damage

Summary of Stress Evaluations of Welded Steel Bridges on Coal-Haul Routes

Stress analyses were performed on continuous girder welded steel bridges on extended weights coal-haul routes. The tests were intended to determine whether extended weight coal trucks pose fatigue problems to those bridges. Measurements were performed by strain gaging selected bridges subject to high coal transport tonnages. Stress measurements were conducted on fatigue-prone weld details or test sites where high tensile stresses were anticipated. Test sites on the bridges were instrumented with strain gages. Strains induced by routine traffic including coal trucks were monitored for periods of one to two weeks. Unattended monitoring of the variable amplitude strain data was performed using rainflow counting. Eighteen successful tests were performed on 15 coal-haul route bridges and one interstate bridge. The derived strain data are provided as stress histograms. Fatigue analyses were performed by expressing the stress histogram data as single-value equivalent stresses. The accumulated number of stress cycles was estimated using 3 different assumptions based upon variations in traffic. Accumulated stress cycles were determined over the current age of each weld detail and a projected service life of 75 years. Susceptibility to fatigue was determined by superimposing the equivalent resolved stresses and total number of cycles as accumulated damage on AASHTO fatigue design curves for the applicable structural details. The fatigue analyses indicate that none of the test bridges with fatigue-prone weld details is susceptible to fatigue cracking either at their current age or over their project 75-year service lives. While coal trucks may induce high live stresses on those bridges, the number of those stress applications was not sufficient to pose fatigue problems. The equivalent resolved stresses measured on the interstate bridge were similar in magnitude to those measured on coal-haul routes. However, the number of stress cycles was greater for the interstate bridge than most of the coal-haul route bridges