Browsing by Author "Schultz, Arturo"

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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.
Determining Economic Strategies for Repair and Replacement of Low Slump Overlays of Bridge Decks
(Minnesota Department of Transportation, Research Services Section, 2007-05) Zimmerman, Justin; Olson, Steven; Schultz, Arturo
In the interest of providing tools for the cost-effective maintenance of an aging inventory of bridges, a method for comparing feasible repair/replacement sequences for low-slump concrete overlays for bridge decks is developed. The method relies on a technique for computing deterioration curves using inspection data from the National Bridge Inventory. Over twenty years of inspection data for bridge decks in Minnesota, which were overlaid with low-slump concrete overlays placed between 1974 and 1981, was used. The deterioration curves were assumed dependent on several material and geometric variables identified by means of a literature review, and the statistical significance of these parameters on deterioration rates was examined. These variables include span length, average daily traffic, and superstructure material type, and piecewise linear deterioration curves were constructed for various subgroups with similar deterioration characteristics. Present value cost analysis was used to price the available options by identifying the sequence of repairs that has the least cost while maintaining a specified performance measure. The present value analysis considers the costs and timing of repair/replacement sequences, inflation, and the discount rate.
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.
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.
Enriched Sensor Data for Enhanced Bridge Weigh-in-Motion (eBWIM) Applications
(Center for Transportation Studies, 2018-11) Kumar, Ravi; Schultz, Arturo; Hourdos, John
Bridge weigh-in-motion (BWIM) systems, which measure bridge deformation under live loading to estimate weights of passing vehicles, have been in development since Moses first introduced the concept in 1979. Despite advances made since its introduction, important limitations for BWIM systems still exist. A feasibility study was performed to determine if some of the limitations—including poor accuracy with multiple vehicle passage, either in tandem or side-by-side; and inability to accurately capture the passage of a vehicle moving at variable speeds—could be overcome by enriching the dataset available to the BWIM system. Non-contact measurements collected in real time on the topside of the bridge can enrich the dataset, and by taking advantage of these measurements a more accurate and effective enriched bridge weigh-in-motion (eBWIM) system can be developed. Several sensing technologies were reviewed including fiber Bragg gratings, MEMS accelerometers, microwave radar sensors, magnetic sensors, active infrared detectors, and video image vehicle detection systems. Preliminary results indicated that there was no clear candidate for a fully mature sensing system that would satisfy all the criteria in this study. However, microwave radar sensors have a reasonably low cost, are the least intrusive, and perform better in all weather conditions compared to the other sensors. A testbed using radar sensors is proposed to investigate the accuracy of the eBWIM system. If the desired accuracy of the eBWIM system can be achieved, its implementations should prove to be invaluable for enforcing bridge weight limits, studying truck traffic patterns, and managing bridge inventories.
Incorporation of Fatigue Detail Classification of Steel Bridges into the Minnesota Department of Transportation Database
(Minnesota Department of Transportation, Research Services Section, 2007-06) Lindberg, Adam; Schultz, Arturo
This report addresses the fatigue and fracture susceptibility of the Minnesota Department of Transportation (Mn/DOT) steel bridge inventory and provides a framework for enumerating fracture and fatigue sensitive details present in steel bridges. It also provides a method for rating the details in terms of their overall frequency and consequence of cracking. The research examines eighteen details identified as possible cracking locations, and a composite rank number is computed based on the details it possesses. The report includes a collection of case studies on cracking due to fatigue and fracture, as well as a timeline of changes to the American Association of State Highway and Transportation Officials Specifications for Highway Bridges and the Minnesota Standard Specifications for Highway Construction. Frequency of occurrence of cracking was defined on the basis of a national survey of state Departments of Transportation, from which the experiences regarding steel bridge cracking were collected from fifteen states. The results are organized in a comprehensive table correlating geometric constraints to rank numbers. The report concludes with a program that calculates a composite rank number for each bridge based upon distribution and rank of the individual details present in the bridge.
Innovative Technologies for Lifetime Extension of an Aging Inventory of Vulnerable Bridges
(Center for Transportation Studies, University of Minnesota, 2011-12) Gastineau, Andrew; Wojtkiewicz, Steven; Schultz, Arturo
This report refines a response modification framework, previously developed by the authors, which combines technological developments in the fields of control systems, health monitoring, and bridge engineering to increase bridge safety. To enhance the modification framework, the numerical bridge model is refined and additional modification apparatuses are added to the numerical model to further develop and confirm the advantages of the response modification approach. A parameter study of the modification apparatus characteristics is carried out to optimize member sizes and modification device characteristics. Finally, a frequency response analysis is carried out to investigate the use of a semi-active system within the scope of the response modification framework.
Remaining Service Life Asset Measure, Phase 1
(Minnesota Department of Transportation, 2018-07) Kumar, Ravi; Matias de Oliveira, Jhenyffer; Schultz, Arturo; Marasteanu, Mihai
There is a critical need to use a common metric, such as a service life parameter, across many different types of infrastructure assets. MnDOT has used the remaining service life (RSL) measure for pavement condition for several years and is starting to use it for bridge condition. In this study, researchers examined what has been done to date and what tools and methodologies are available nationally and internationally, and made recommendations on a future measure that can be used to show the "true" condition of the system. First, a literature review was performed to summarize current methods used in asset management and life-cycle cost analyses. A survey was also performed to collect information from agencies around the country. An assessment of current practice used by MnDOT Bridge Office and Materials and Road Research Office was performed next to identify similarities and differences between the two approaches. Based on the information collected, suggestions for a common method were presented and guidelines for a work plan for a follow-up phase 2 were developed.
Response Modification for Enhanced Operation and Safety of Bridges
(University of Minnesota Center for Transportation Studies, 2011-08) Gastineau, Andrew; Schultz, Arturo; Wojtkiewicz, Steven
This report shows that safe extension of the service life of existing bridge structures is possible through bridge health monitoring and structural response modification. To understand bridge health monitoring and structural response modification and control, it is necessary to examine: 1) common bridge vulnerabilities, 2) bridge loading models, 3) response modification devices, and 4) bridge monitoring systems. The efficacy of response modification techniques on a realistic bridge system were demonstrated using the Cedar Avenue Bridge in Minnesota as a specific example. The Cedar Avenue Bridge is a steel tied arch bridge which means that it is fracture critical. Due to the non-redundant nature of a fracture critical bridge, fatigue failure could be catastrophic and is of concern. Previous research has shown that stress concentrations exist at the joints where the hangers and floor beams are attached to the box girder [7]. Using a simulation of response modification on the Cedar Avenue Bridge model, stress ranges have been reduced on these specific details that are of concern. Modeling using a scissor jack and simple damping device has shown that stress ranges can be reduced by approximately 39% which can lead to life extension of as much as 346%.
Strength and Stability of Prestressed Concrete Through-Girder Pedestrian Bridges Subjected to Vehicular Impact
(Minnesota Department of Transportation, Research Services Section, 2007-01) Baran, Eray; Schultz, Arturo; French, Catherine
Two issues regarding the prestressed concrete through-girder pedestrian bridge system are investigated. The first issue concerns the ductility of prestressed concrete girders in these bridges because the section that is typically used may be considered to be over-reinforced according to AASHTO LRFD Bridge Specifications. Response of the section, including neutral axis location, strand stress at ultimate capacity, and moment capacity, predicted by AASHTO Standard and AASHTO LRFD Specifications are compared with the sectional response determined from nonlinear strain compatibility analyses. Modifications are proposed to the AASHTO LRFD procedure to rectify the errors in predicting sectional response. The second issue that was investigated concerns the strength and stability of prestressed concrete through-girder pedestrian bridges when subjected to impact by over-height vehicles. Three-dimensional finite element models of entire bridges and subassemblages were used to evaluate the strength, stiffness, and ductility characteristics of the bridge system and connection details. Accurate representation of the bridge details in the finite element models were assured by utilizing experimentally determined load-deformation characteristics for the connections. Results showed that significant improvements in the lateral load-deflection behavior of the bridge system could be obtained by implementing alternate connection schemes, and that concrete side-walls should be provided at girder ends.

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