Browsing by Subject "Bridges"

Now showing 1 - 12 of 12

Bridge Health Monitoring and Inspections – A Survey of Methods
(Minnesota Department of Transportation, 2009-09) Gastineau, Andrew; Johnson, Tyler; Schultz, Arturo
Since the collapse of the I-35W bridge in August 2007, bridge health monitoring has become an area of intense interest. This report defines terminology related to bridge health monitoring and provides a general glossary of available monitoring systems. The glossary is meant to help readers make an informed decision by understanding how different systems function and their strengths and weakness. The authors developed a questionnaire to send to commercial companies offering monitoring systems. Of the 72 questionnaires that were sent to commercial companies, 38 companies responded and are included in this report. From information provided with these questionnaires, available commercial systems are briefly summarized. Criteria for system evaluation were developed to help the bridge owner narrow down company choices for bridge application. After the owner answers a set of questions pertaining to a particular bridge, a program developed in Microsoft EXCEL helps the bridge owner decide the best system for a particular situation. An example is provided for program clarity. Once company choice is narrowed down, additional criteria were developed to aid in final product choice.
Bridge Scour Monitoring Technologies: Development of Evaluation and Selection Protocols for Application on River Bridges in Minnesota
(Minnesota Department of Transportation, 2010-03) Lueker, Matthew; Marr, Jeff; Ellis, Chris; Winsted, Vincent; Akula, Shankar Reddy
Bridge failure or loss of structural integrity can result from scour of riverbed sediment near bridge abutments or piers during high-flow events in rivers. In the past 20 years, several methods of monitoring bridge scour have been developed spanning a range of measurement approaches, complexities, costs, robustness, and measurement resolutions. This project brings together the expertise of Minnesota Department of Transportation (Mn/DOT) bridge engineers and researchers, university hydraulic and electrical engineers, field staff, and inspectors to take the first steps toward development of robust scour monitoring for Minnesota river bridges. The team worked with Mn/DOT engineers to identify variables of scour critical bridges that affect the application of scour monitoring technology. The research team will used this information to develop a Scour Monitoring Decision Framework (SMDF) that will aid Mn/DOT in selecting the best technologies for specific sites. The final component of the project will involve testing the SMDF on five bridges in a case-study type demonstration; work plans for two of the sites were developed for demonstration of deployed instrumentation.
Development of an Advanced Structural Monitoring System
(Minnesota Department of Transportation Research Services Section, 2010-11) Schultz, Arturo; Thompson, David
With bridge infrastructure in Minnesota aging, advancing techniques for ensuring the safety of bridges and motorists is a fundamental goal of the Minnesota Department of Transportation (Mn/DOT). As such, developing health monitoring systems for fracture critical bridges is an essential objective in meeting the stated goal. This report applies the methodology and uses the information of a previous Mn/DOT report to investigate, select, and design a bridge health monitoring system for the Cedar Avenue Bridge which is a fracture critical tied arch bridge in Burnsville, Minnesota. An investigation of monitoring needs for the Cedar Avenue Bridge was undertaken. In addition, the authors reviewed literature with the goal of determining the most applicable monitoring technology that is commercially available and which fulfills the required bridge monitoring needs. Once a monitoring technology was selected, the authors selected a vendor, using a computer-based program developed in the aforementioned Mn/DOT report, to select a suggested system of monitoring equipment for Mn/DOT to purchase. Finally, the report describes multiple alternatives for monitoring scales, scopes, locations, and capabilities, with global monitoring of the most critical members and connections of the bridge as the authors’ recommendation. A procedure for installation of the suggested bridge health monitoring system follows the authors’ recommendations and is applicable to any of the monitoring alternatives presented in this report.
Development of the Next Generation Metro-Wide Simulation Models for the Twin Cities' Metropolitan Area: Mesoscopic Modeling
(2011-01) Liu, Henry X.; Danczyk, Adam; He, Xiaozheng
The collapse of the Interstate 35W Bridge over the Mississippi River in Minneapolis resulted in unexpected loss of life and had serious consequences on mobility and accessibility in the Twin Cities metropolitan area. In response to the network disruption caused by the bridge collapse, a number of traffic restoration projects were proposed and rapidly implemented by MnDOT. Selection and prioritization of these projects, however, was based mainly on engineering judgment and experience. The only decision-support tool available to traffic engineers was the regional transportation planning model, which is static in nature and decennial. In this work, the Twin Cities metropolitan area is simulated using a mesoscopic traffic simulator in the AIMSUN software. After establishing the mesoscopic simulation model, we attempt to utilize the calibrated mesoscopic simulation model to evaluate drivers’ perceived cost evolution to explain the traffic dynamics on the Twin Cities road network after the unexpected collapse of the I-35W Bridge over the Mississippi River. Given the observation of largely underutilized sections of network, it is proposed that the tragedy generated a perceived travel cost to discourage commuters from using these sections. Applying a mesoscopic simulation model provided by AIMSUN, the perceived costs on cordon lines after the I-35W Bridge collapse were suggested to be best described as an exponential decay cost curve. The proposed model is applicable to both practitioners and researchers in traffic-related fields by providing an understanding of how traffic dynamics will evolve after a long-term, unexpected network disruption.
Enhancing Bridge Safety and Operation with Response Modification (Research Brief)
(Center for Transportation Studies, University of Minnesota, 2012-06) Center for Transportation Studies; Schultz, Arturo
This two-page document summarizes report CTS 11-14, Response Modification for Enhanced Operation and Safety of Bridges, about affordable solutions to safely extend bridge life in the U.S.
Load Rating of Composite Steel Curved I-Girder Bridges through Load Testing with Heavy Trucks
(Minnesota Department of Transportation, 2006-10) Krzmarzick, Dan P.; Hajjar, Jerome F.
Current techniques for rating of horizontally curved composite steel I-girder bridges often use approximate methods of analysis based on assessment of individual straight girders with altered properties to account for member curvature. This project investigates the behavior and rating of these bridges through load testing with heavy trucks. A five-span continuous two-girder horizontally curved steel I-girder bridge was load tested. Strain and displacement measurements were obtained for the main girders, diaphragms, lateral wind bracing, bearings, composite interaction, and areas of high strain concentrations near stiffener details. Forty-three static tests with different truck load patterns were conducted along with thirteen dynamic tests to assess the bridge response. A linear elastic grillage-based model of the bridge was used to simulate the load patterns. A sensitivity study was carried out based on the tested bridge along with simulations of two other bridges previously tested elsewhere so as to assess the robustness of grillage analysis for use in load rating of horizontally curved steel I-girder bridges. Recommendations are made outlining rating of horizontally curved composite steel I-girder bridges through the use of grillage-based analysis, with and without the use of load testing, and within the context of the AASHTO Load and Resistance Factor Rating (LRFR) and Load Factor Rating (LFR) procedures.
Modeling and Monitoring the Long-Term Behavior of Post-Tensioned Concrete Bridges
(Minnesota Department of Transportation, 2014-11) French, Catherine E.W.; Shield, Carol K.; Hedegaard, Brock D.
The time-dependent and temperature-dependent behavior of post-tensioned concrete bridges were investigated through a case study of the St. Anthony Falls Bridge, consisting of laboratory testing of concrete time-dependent behaviors (i.e., creep and shrinkage), examination of data from the in situ instrumented bridge, and time-dependent finite element models. Laboratory results for creep and shrinkage were measured for 3.5 years after casting, and the data were best predicted by the 1978 CEB/FIP Model Code provisions. To compare the in situ readings to constant-temperature finite element models, the time-dependent behavior was extracted from the measurements using linear regression. The creep and shrinkage rates of the in situ bridge were found to depend on temperature. An adjusted age using the Arrhenius equation was used to account for the interactions between temperature and time-dependent behavior in the measured data. Results from the time-dependent finite element models incorporating the full construction sequence revealed that the 1990 CEB/FIP Model Code and ACI-209 models best predicted the in situ behavior. Finite element analysis also revealed that problems associated with excessive deflections or development of tension over the lifetime of the bridge would be unlikely. The interactions between temperature and time-dependent behavior were further investigated using a simplified finite element model, which indicated that vertical deflections and stresses can be affected by the cyclic application of thermal gradients. The findings from this study were used to develop an anomaly detection routine for the linear potentiometer data, which was successfully used to identify short-term and long-term artificial anomalies in the data.
Modeling and monitoring the long-term behavior of post-tensioned concrete bridges
(2014-06) Hedegaard, Brock Daniel
The time-dependent and temperature-dependent behavior of post-tensioned concrete bridges were investigated through a case study of the St. Anthony Falls Bridge, consisting of laboratory testing of concrete time-dependent behaviors (i.e., creep and shrinkage), examination of data from the in situ instrumented bridge, and time-dependent finite element models. Laboratory results for creep and shrinkage were measured for 3.5 years after casting, and the data were best predicted by the 1978 CEB/FIP Model Code provisions. To compare the in situ readings to constant-temperature finite element models, the time-dependent behavior was extracted from the measurements using linear regression. The creep and shrinkage rates of the in situ bridge were found to depend on temperature. An adjusted age using the Arrhenius equation was used to account for the interactions between temperature and time-dependent behavior in the measured data. Results from the time-dependent finite element models incorporating the full construction sequence revealed that the 1990 CEB/FIP Model Code and ACI-209 models best predicted the in situ behavior. Finite element analysis also revealed that problems associated with excessive deflections or development of tension over the lifetime of the bridge would be unlikely. The interactions between temperature and time-dependent behavior were further investigated using a simplified finite element model, which indicated that vertical deflections and stresses can be affected by the cyclic application of thermal gradients. The findings from this study were used to develop an anomaly detection routine for the linear potentiometer data, which was successfully used to identify short-term and long-term perturbations in the data.
Protocols and Criteria for Acoustic Emission Monitoring of Fracture-Critical Steel Bridges
(Center for Transportation Studies, University of Minnesota, 2015-06) Tillmann, Anton S.; Schultz, Arturo E.; Campos, Javier E.
With bridge infrastructure in Minnesota aging, advancing techniques for ensuring bridge safety is a fundamental goal of the Minnesota Department of Transportation (MnDOT). Developing health monitoring systems for fracture-critical bridges is an essential objective in meeting the stated goal. This report documents the implementation of two, 16-sensor, acoustic emission monitoring systems in one of the tie girders of the Cedar Avenue Bridge, which is a fracture-critical tied arch bridge spanning the Minnesota River between Bloomington and Eagan, MN. The goal of the project is to develop a process for using acoustic emission technology to monitor one of the girders of the bridge while continuously collecting data from the monitoring systems. Given the cost of acoustic emission sensing equipment, an approach was adopted to space the sensors as widely as possible. Fracture tests were conducted on a specimen acoustically connected to the bridge to simulate fracture in a bridge member. Sets of criteria were developed to differentiate between acoustic emission data collected during fracture and ambient bridge (i.e. AE noise) data. The sets of criteria were applied to fracture test data and AE noise data to determine the validity of the criteria. For each criteria set, a period of Cedar Avenue Bridge monitoring data was analyzed. The results of the analysis of each period showed that the criteria could differentiate between the bridge AE noise data and the fracture test data. The AE noise data never met all of the criteria in the set, whereas all criteria were met during each of the applicable fracture tests.
Scour Monitoring Technology Implementation
(Center for Transportation Studies, University of Minnesota, 2014-09) Lueker, Matthew; Marr, Jeff
Bridge scour is the removal of sediment around bridge foundations and can result in the failure of the bridge. Scour monitoring is performed to identify unacceptable scour on bridges considered to be scour critical and determine when scour reaches elevations that could cause potential bridge failure. Two types of monitoring are available: portable monitoring and fixed monitoring. Prior to this project, MnDOT was only using portable monitoring devices, which requires the deployment of personnel to make physical measurements of scour depths. For some scour critical bridges, especially during high-water events, fixed instrumentation capable of continuous scour monitoring was preferred, but MnDOT lacked the experience or expertise to install this type of equipment. This project installed fixed monitoring equipment at two bridge sites and monitored them for three years to determine the effectiveness and reliability of fixed scour monitoring deployments. Several device options were installed to allow MnDOT to analyze the installation and performance of different types of sensors. Both systems operated for the three years with some outages due to various causes but overall performance was acceptable. The outages were mostly related to power issues and communication issues. Valuable lessons were learned through the deployment, which may be applied to future installations. The deployment executed in this project has provided the confidence to deploy other fixed scour monitoring equipment at key bridges around the state of Minnesota. In addition, the data collected during deployment of the scour monitoring equipment has been stored and provides insight into scour processes. This data can be used by other research groups for design or research purposes.
Stresses in Steel Curved Girder Bridges
(Minnesota Department of Transportation, 1996-08) Galambos, Theodore V.; Hajjar, Jerome F.; Leon, Roberto T.; Huang, Wen-Hsen; Pulver, Brian E.; Rudie, Brian J.
Steel curved I-girder bridge systems may be more susceptible to instability during construction than bridges constructed of straight I-girders. The primary goal of this project is to study the behavior of the steel superstructure of curved steel Igirder bridge systems during all phases of construction, and to ascertain whether the linear elastic analysis software used by Mn/DOT during the design process represents well the actual stresses in the bridge. Sixty vibrating wire strain gages were applied to a two-span, four-girder bridge, and the resulting stresses and deflections were compared to computational results for the full construction sequence of the bridge. The computational results from the Mn/DOT analysis software were first shown to compare well with results from a program developed specifically for this project (called the "UM program"), since the latter permits more detailed specification of actual loading conditions on the bridge during construction. The UM program, in turn, correlated well with the field measurements, especially for the primary flexural stresses. Warping stresses induced in the girders, and the stresses in the crossframes, were more erratic, but showed reasonable correlation. It is concluded that Mn/DOT's analysis software captures the behavior well for these types of curved girder bridge systems, and that the stresses in these bridges may be relatively low if their design is controlled largely by stiffness.
Traffic Flow and Road User Impacts of the Collapse of the I- 35W Bridge over the Mississippi River
(Minnesota Department of Transportation, Research Services Section, 2010-07) Zhu, Shanjiang; Levinson, David; Liu, Henry; Harder, Kathleen; Dancyzk, Adam
Major network disruptions have significant impacts on local travelers. A good understanding of behavioral reactions to such incidents is crucial for traffic mitigation, management, and planning. Existing research on such topics is limited. The collapse of the I-35W Mississippi River Bridge (August 1, 2007) abruptly disrupted habitual routes of about 14,000 daily trips and forced even more travelers to adapt their travel pattern to evolving network conditions. The opening of the replacement bridge on November 18, 2008 generated another disturbance (this time predictable) on the network. Such “natural” experiments provide unique opportunities for behavioral studies. This study focuses on the traffic and behavioral reactions to both bridge collapse and bridge reopening and contributes to general knowledge by identifying unique patterns following different events. Three types of data collection efforts have been conducted during the appropriate frame of reference (i.e. before vs. after bridge reconstruction): 1) GPS tracking data and associated user surveys, 2) paper and internet-based survey data gauging travel behavior in the post-bridge reconstruction phase, and 3) aggregate data relating to freeway and arterial traffic flows, traffic control, and transit ridership. Differences in reactions to planned versus unplanned events were revealed. Changes in travel cost were evaluated and their temporal and spatial patterns were analyzed. This report concludes with thorough discussions of findings from this study and policy implications.

University Digital Conservancy

Browse by Subject

Browsing by Subject "Bridges"