Browsing by Subject "I-35W Bridge"

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    A Computational Study of the I-35W Bridge Collapse
    (Center for Transportation Studies, University of Minnesota, 2009-10) Liao, Minmao; Okazaki, Taichiro
    Reported evidence suggests that failure of gusset plates initiated the collapse of the I-35W Bridge in Minneapolis, Minnesota. The particular gusset plates were at a panel point designated as U10. Therefore, a computational study was conducted on the condition of the U10 gusset plates at the time of bridge collapse. The primary objectives of this study were: (1) to evaluate previous research and existing design methods for gusset plate connections; (2) to examine the mechanical condition of the U10 gusset plates at the time of the collapse; (3) to examine possible scenarios that led to the collapse of the entire bridge; and (4) to identify research needs to improve the design methods for gusset plate connections. The forces delivered to panel point U10 were reproduced using available information of the bridge. The truss forces were introduced to detailed nonlinear, three-dimensional finite element models to calculate stress and strain states of the gusset plates. The results indicate that substantial portions of the U10 gusset plates were yielded at the time of collapse, confirming earlier findings from federal and state investigations. Insufficient strength of the gusset plate, along with weight increase due to past deck reconstruction and construction material and equipment staged on the day of collapse, were identified as the main contributing factors to the substantial yielding. It is important to note that, even with the weight increase, the gusset plates would not have yielded substantially if the gusset plates had adequate thickness. The results also suggest that the interaction of compression and shear played an important role in the gusset plate failure and should be addressed in gusset plate design. This interaction is not well understood based on available research.
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    Instrumentation, Monitoring, and Modeling of the I-35W Bridge
    (Minnesota Department of Transportation, 2012-08) French, Catherine E.W.; Shield, Carol K.; Stolarski, Henryk K; Hedegaard, Brock D.; Jilk, Ben J.
    The new I-35W Bridge was instrumented incorporating "smart bridge technology" by Figg Engineering Group in conjunction with Flatiron-Manson. The purpose of the instrumentation was to monitor the structure during service, and to use this information to investigate the design and performance of the bridge. Instrumentation included static sensors (vibrating wire strain gages, resistive strain gages and thermistors in the foundation, bridge piers, and superstructure, as well as fiber optic sensors and string potentiometers in the superstructure) and dynamic sensors (accelerometers in the superstructure). Finite element models were constructed, taking into account measured material properties, to further explore the behavior of the bridge. The bridge was tested using static and dynamic truck load tests, which were used, along with continually collected ambient data under changing environmental conditions, to validate the finite element models. These models were applied to gain a better understanding of the structural behavior, and to evaluate the design assumptions presented in the Load Rating Manual for the structure. This report documents the bridge instrumentation scheme, the material testing, finite element model construction methodology, the methodology and results of the truck tests, validation of the models with respect to gravity loads and thermal effects, measured and modeled dynamic modal characteristics of the structure, and documentation of the investigated assumptions from the Load Rating Manual. It was found that the models accurately recreated the response from the instrumented bridge, and that the bridge had behaved as expected during the monitoring period.
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    A Model for Emergency Preparedness and Response in the 21st Century: A Closer Look at the I-35 W Bridge Collapse and the City of Minneapolis’s Crisis Management System
    (Hubert H. Humphrey Institute of Public Affairs, 2009-05-13) Doyle, Jeremiah
    One of the most critical roles for local government is to have an efficient and effective emergency preparedness and response system. A successful emergency preparedness and response system plans for and protects its citizens from potential crises, both expected and unexpected. The need for an effective system could not be made more evident than on September 11th, 2001 after the terrorist attacks on the World Trade Center and the Pentagon. Many valuable lessons were learned after that response including the need for clearer strategic planning and better communications. Six years later, the City of Minneapolis encountered an unexpected disaster when the I-35 W Bridge collapsed during rush hour on Wednesday, August 1st 2007. The emergency response to the I-35 W Bridge collapse was swift and massive with more than 140 different organizations involved in the effort. It took emergency responders less than two hours to rescue every survivor, and as I will argue throughout the paper, the crisis response to the I-35 W Bridge collapse is a model for effective emergency preparedness and response in the 21st century. There were two very important lessons learned from this analysis. First, hierarchical and network characteristics within the crisis management system proved to be one of the most significant reasons the emergency response was so effective. The crisis management system utilized during the I-35 W Bridge collapse was the Incident Command System. The Minneapolis response illustrates that a successful crisis management system requires a balance between hierarchical and network elements. The second most important lesson learned was Mayor R.T. Rybak’s decision to attend the Federal Emergency Management Agency’s (FEMA’s) training course in 2002. Thisdecision played a crucial role in the response and recovery efforts for two reasons. First, it was the initial step towards relationship building, and second, it illustrated weaknesses in the city’s emergency response, which were amended before the 2007 I-35 W Bridge collapse.