Fatigue Behavior of Beam Diaphragm Connections with Intermittent Fillet Welds: Part II, Brittle Fracture Examination of the I-64 Blue River Bridge

This report is the second of a two-part, three volume final report presenting the findings of the research work that was undertaken to evaluate the behavior of Indiana highway bridges with diaphragm members welded directly to the web of the primary beams and girders. Fatigue cracks have been observed at several bridges that utilize the welded diaphragm connection. The seriousness of the cracking and the corresponding potential risk on the integrity of the bridge superstructure were assessed. Inspection and repair guidelines for bridges with the welded diaphragm connections were also developed as part of the research effort. This volume presents the results of laboratory fatigue tests that were conducted to evaluate the cyclic life of staggered and non-staggered diaphragm connections. The performance of three different repair and retrofit procedures on the cyclic life of the welded diaphragm connection was also studied. Analytical models of the cracked diaphragm connection were developed to study the expected response under field loading conditions. Recommendation for implementation of inspection, repair, and retrofit procedures are presented. The titles of the three volumes (Report Number in parentheses) are listed: Part I, Volume 1: Field Evaluation (FHWA/IN/JTRP-2001/10-I-1) Part I, Volume 2: Laboratory Fatigue Evaluation (FHWA/IN/JTRP-2001/10-I-2) Part II: Brittle Fracture Examination of the I-64 Blue River (FHWA/IN/JTRP-2001/10-II)This report is the third of a two-part, three volume final report presenting the findings of the research work that was undertaken to evaluate the behavior of Indiana highway bridges with diaphragm members welded directly to the web of the primary beams and girders. Fatigue cracks have been observed at several bridges that utilize the welded diaphragm connection. The seriousness of the cracking and the corresponding potential risk on the integrity of the bridge superstructure were assessed. Inspection and repair guidelines for bridges with welded diaphragm connections were also developed as part of the research effort. This volume presents the results of an evaluation of a brittle fracture crack that was discovered in one of the welded plate girder members of the I-64 Blue River Bridge in Harrison County of southern Indiana. The crack, which nearly severed the exterior girder on the northern side of the east-bound structure, was located in the middle span of the three-span bridge structure. The crack extended for most of the plate girder depth before it was arrested in the compression region near the top of the girder and the concrete deck. The primary purpose of the research study was to examine the causes of the brittle fracture of the I-64 Blue River Bridge girder. In addition to understanding the reasons for the brittle fracture, possible repair and retrofit procedures were formulated to improve the fracture resistance of bridges with details similar to the Blue River Bridge. The titles of the three volumes (Report Number in parentheses) are listed below: Part I, Volume 1: Field Evaluation (FHWA/IN/JTRP-2001/10-I-1) Part I, Volume 2: Laboratory Fatigue Evaluation (FHWA/IN/JTRP-2001/10-I-2) Part II: Brittle Fracture Examination of the I-64 Blue River Bridge (FHWA/IN/JTRP-2001/10-II

A Test of Direct and Partially Mediated Relationships Between Leader Member Exchange, Job Embeddedness, Turnover Intentions, and Job Search Behaviors in a Southern Police Department

Job embeddedness has been found to predict turnover intentions, job search behaviors and turnover, and job embeddedness researchers assert, but have not tested, that job embeddedness is a mediator of other organizationally significant factors relative to organizational outcomes. A relationship not previously explored is the role of a supervisor in job embeddedness, which was operationalized in this study as leader-member exchange. A single panel survey was conducted in a police department in the southern United States with 276 current members holding the rank of police officer. Usable surveys were completed by 128 of those police officers, which is a response rate of 46 percent. These surveys assessed the participant\u27s perceptions of leader-member exchange, organizational job embeddedness, turnover intentions, and job search behaviors. The results indicated statistically significant positive correlations between leader-member exchange and the organizational job embeddedness, and significant negative correlations between leader-member exchange and turnover intentions, leader-member exchange and job search behaviors, organizational job embeddedness and turnover intentions, and organizational job embeddedness and job search behaviors. The literature suggested an a priori model in which the exogenous variable leader-member exchange directly affected organizational job embeddedness, which directly affected turnover intentions, which directly affected job search behaviors. In this a priori model the relationship between leader-member exchange and turnover intentions and job search behaviors was mediated by organizational job embeddedness. A measurement model, a saturated structural model, and 4 nested models were tested through structural equation modeling and each was found to be an acceptable fit to the data. There was no statistically significant difference between any of the models and the most parsimonious was accepted. In that model leader-member exchange had a direct positive effect on organizational job embeddedness, which in turn had a direct negative effect on turnover intentions, which in turn had a direct positive effect on job search behaviors. These findings support the proposition that having a good relationship with a supervisor improves the extent to which the employee is embedded in the organization and that embeddedness reduces turnover intentions which reduces job search behaviors

The Examination of Infra-Red Techniques for Inspection of Steel Structures I & II

Infra-red thermography systems that have been developed over the last few years offer great potential to locate and discover flaws in steel highway bridge structures at a relatively early stage in their development. Under ideal conditions, the use of infra-red instrumentation should allow bridge inspection personnel to rapidly scan the structure and determine if a potential structural problem has developed. If a problem spot is located by the infra-red camera, then the trouble spot can be examined carefully to determine the need for corrective maintenance. The primary purpose of this research study is to evaluate the accuracy and reliability of sensitive infra-red equipment for detecting fatigue cracks in steel highway bridge structures and components. The performance and sensitivity of one particular infra-red system was explored by conducting tests on two different specimen types in the laboratory, followed by a check of the equipment under field conditions. Crack detection sensitivity in the laboratory was evaluated using a center-hole test coupon geometry as well as a welded attachment plate detail. The test samples were subjected to cyclic loading to initiate and propagate a fatigue crack. Control variables for the infra-red system were then varied to evaluate the optimal conditions. The field tests were conducted to assess the equipment limitations and performance under field conditions. The detail inspected involved a vertical plate that was welded to the web of a beam member and used to attach transverse diaphragm cross-frame members; the diaphragm connection plate was selected for inspection because it was known that fatigue cracks had developed at the end of a number of the vertical plates. It was found that infra-red inspection could be used successfully to detect fatigue cracks in steel bridge members and components if the crack had propagated through the thickness. Consequently, the crack size that could be reliably and consistently detected was not significantly different from that which could be detected from a careful visual inspection. Moreover, a number of difficulties were encountered when using infra-red inspection in the field. Limitations were encountered in the field related to mobility of the equipment, calibration requirements, operator skill level required, and the variable effects of environmental factors that influence the detection capabilities

Bridge Preservation Treatments and Best Practices

Aging of the bridge infrastructure inventory has caused Department of Transportation agencies to critically focus on bridge preservation and replacement needs, while often faced with constrained or reduced budgets every year. A strategic bridge preventive maintenance program has been shown to be an effective way to preserve and extend bridge service lives. A bridge preventive maintenance program is related to routine practices that are repeated with some particular frequency to obtain the best results. Moreover, it is well known that frequently performing less-costly preventive maintenance activities results in a more efficient alternative than performing fewer expensive repairs/rehabilitation or even replacements of bridge elements. The objective of this research was to review bridge maintenance activities recommended by specialized literature, to examine maintenance activities currently conducted by the various INDOT districts, and also to review maintenance activities performed by several other DOT agencies. Based on the results of this review, a list of ten new and enhanced bridge preventive maintenance activities was identified to improve the effectiveness of bridge maintenance operations in Indiana. The required conditions and frequency to perform each activity was analyzed, and the cost and benefit of such operations was studied to ensure that the proposed activities are economically feasible and sustainable

Pack Rust Identification and Mitigation Strategies for Steel Bridges

Pack rust or crevice corrosion is a type of localized corrosion. When a metal is in contact with a metal, or even non-metal, the metal starts to corrode, and rust starts to pack in between the surfaces. When significant development of pack rust occurs, it can cause overstressing of bolts and rivets causing them to fail, and it can bend connecting plates and member elements thus reducing their buckling capacity. Thus it is important to mitigate the formation and growth of pack rust in bridges. This study was conducted to determine if pack rust occurs frequently and thereby may pose a problem in the state of Indiana. The study is divided into three primary tasks. The first part of the study involves understanding the parameters involved in the initiation process of crevice corrosion and post-initiation crevice corrosion process. The second part of the study involves reviewing existing mitigation strategies and repair procedures used by state DOTs. The third part of the study involves identifying steel bridges with pack rust in Indiana. Analyses were performed on the data collected from Indiana bridges that have pack rust. This involved finding the components and members of bridges which are most affected by pack rust and finding parameters which influence the formation of pack rust. Pack rust in the steel bridges were identified using the INDOT inspection reports available through BIAS system. The study revealed that good maintenance practices helped in reducing pack rust formation. The study identified locations on steel bridges which have a high probability towards pack rust formation. A mitigating strategy possessing qualities which can show promising results is identified

Fatigue Behavior of Beam Diaphragm Connections With Intermittent Fillet Welds, Part I, Volume 1, Field Evaluation

This report is the first of a two-part, three volume final report presenting the findings of the research work that was undertaken to evaluate the behavior of Indiana highway bridges with diaphragm members welded directly to the web of the primary beams and girders. Fatigue cracks have been observed at several bridges that utilize the welded diaphragm connection. The seriousness of the cracking and the corresponding potential risk on the integrity of the bridge superstructure were assessed. Inspection and repair guidelines for bridges with the welded diaphragm connections were also developed as part of the research effort. This volume presents the results of load tests on two bridge structures with different diaphragm connections. The importance of diaphragm configuration on the stress levels developed at the connection detail is presented. The titles of the three volumes (Report Number in parentheses) are listed below: Part I, Volume 1: Field Evaluation (FHWA/IN/JTRP– 2001/10 – I-1) Part I, Volume 2: Laboratory Fatigue Evaluation (FHWA/IN/JTRP-2001/10-I-2) Part II: Evaluation of Blue River Bridge Fracture (FHWA/IN/JTRP-2001/10-II

Review of Load Rating and Posting Procedures and Requirements

All states are required to load rate and post bridges in order to comply with federal standards. Load ratings are performed in order to determine the safe live load capacity of a bridge, considering the existing conditions of the bridge. Based on the load ratings, the bridge is evaluated for load posting or strengthening. The Indiana Department of Transportation (INDOT) was notified that their practice for load rating and posting did not satisfy 23 CFR 650.313. The purpose of this study was to summarize and compare load rating and posting procedures used in other states and to provide recommendations and information necessary to modify the load rating and posting procedures in INDOT’s Bridge Inspection Manual (Part 3: Load Rating) in order to satisfy 23 CFR 650.313. In order to understand how load rating and posting is performed in other states, department of transportation (DOT) manuals were examined, questionnaires were sent to states, and additional states of interest were surveyed. The American Association of State Highway and Transportation Officials (AASHTO) The Manual for Bridge Evaluation, Second Edition, which is the current specification for load rating and posting bridges was reviewed, as well as older AASHTO bridge evaluation manuals. Based on this information, revisions were proposed to the INDOT Bridge Inspection Manual (Part 3: Load Rating) in order to eliminate current deficiencies

Bridge Load Rating

The inspection and evaluation of bridges in Indiana is critical to ensure their safety to better serve the citizens of the state. Part of this evaluation includes bridge load rating. Bridge load rating, which is a measure of the safe load capacity of the bridge, is a logical process that is typically conducted by utilizing critical information that is available on the bridge plans. For existing, poorly-documented bridges, however, the load rating process becomes challenging to adequately complete because of the missing bridge information. Currently, the Indiana Department of Transportation (INDOT) does not have a prescribed methodology for such bridges. In an effort to improve Indiana load rating practices INDOT commissioned this study to develop a general procedure for load rating bridges without plans. The general procedure was developed and it was concluded that it requires four critical parts. These parts are bridge characterization, bridge database, field survey and inspection, and bridge load rating. The proposed procedure was then evaluated on two bridges in Indiana that do not have plans as a proof of concept. As a result, it was concluded that load rating of bridges without plans can be successfully completed using the general procedure. A flowchart describing the general procedure was created to make the load rating process more user-friendly. Additional flowcharts that summarize the general procedure for different type of bridges were also provided

Steel Bridge Coating Evaluation and Rating Criteria

The aim of the study is to gather information on three topics: (1) the evaluation and rating of steel bridge protective coatings, (2) coating systems used by various states throughout the United States, and (3) maintenance painting procedures employed by various state department of transportation agencies (DOTs). First, it was found that most state DOTs use either an Element Level type rating of the coating system or a 9–0 NBI type rating; many state DOTs use both methodologies, with one used for state bridges and the other for local bridges. Second, for coating systems, it was found that there is a great deal of uniformity of the steel bridge coating systems used in the United States, with three-coat paint systems being the most common. Third, it is believed that maintenance painting can extend the useful life of bridge coatings. However, many state DOTs report that the cost of maintenance painting has increased due to many factors that involve available personnel, proper training, and increased regulations on the removal and application of steel bridge coatings. Consequently, many DOTs no longer perform maintenance painting, other than emergency repairs, and simply wait until the entire bridge needs to be re-coated and contract the work out. Lastly, an NBI 9–0 type rating procedure for steel bridge coatings is proposed for possible consideration and implementation by INDOT

Pack Rust: Mitigation Strategy Effectiveness

As of 2013, the damage caused by corrosion on highway bridges has been estimated to cost approximately 14 billion dollars annually, and this cost has been increasing over the years. Corrosion is one of the natural phenomena that has been slowly deteriorating infrastructure systems across the United States. One of the most problematic types of corrosion is crevice corrosion, which is defined as the formation of rust between overlapping surfaces, such as the case of a splice connection where flanges are attached by splice plates. A significant number of steel bridges in Indiana have developed crevice corrosion in splice connections. Therefore, this research focuses on the crevice corrosion, or “pack rust,” occurring in these structural elements. The application of coatings alone has not been enough to stop pack rust at these connections. In an attempt to look for approaches that can effectively mitigate this problem and maintain the designed service life of bridges, different strategies have been studied and tested. It was found that the proper use of penetrating sealers can be effective in delaying the development of further corrosion, while the use of caulk alone may be problematic as a repair method