Evaluation of Steel Bridges, Volumes I & II, TR-493, 2007

This report is divided into two volumes. This volume (Volume I) summarizes a structural health monitoring (SHM) system that was developed for the Iowa DOT to remotely and continuously monitor fatigue critical bridges (FCB) to aid in the detection of crack formation. The developed FCB SHM system enables bridge owners to remotely monitor FCB for gradual or sudden damage formation. The SHM system utilizes fiber bragg grating (FBG) fiber optic sensors (FOSs) to measure strains at critical locations. The strain-based SHM system is trained with measured performance data to identify typical bridge response when subjected to ambient traffic loads, and that knowledge is used to evaluate newly collected data. At specified intervals, the SHM system autonomously generates evaluation reports that summarize the current behavior of the bridge. The evaluation reports are collected and distributed to the bridge owner for interpretation and decision making. Volume II summarizes the development and demonstration of an autonomous, continuous SHM system that can be used to monitor typical girder bridges. The developed SHM system can be grouped into two main categories: an office component and a field component. The office component is a structural analysis software program that can be used to generate thresholds which are used for identifying isolated events. The field component includes hardware and field monitoring software which performs data processing and evaluation. The hardware system consists of sensors, data acquisition equipment, and a communication system backbone. The field monitoring software has been developed such that, once started, it will operate autonomously with minimal user interaction. In general, the SHM system features two key uses. First, the system can be integrated into an active bridge management system that tracks usage and structural changes. Second, the system helps owners to identify damage and deterioration.

Evaluation of a Bridge Constructed using High Performance Steel, May 2006

Of the approximately 25,000 bridges in Iowa, 28% are classified as structurally deficient, functionally obsolete, or both. Because many Iowa bridges require repair or replacement with a relatively limited funding base, there is a need to develop new bridge materials that may lead to longer life spans and reduced life-cycle costs. In addition, new and effective methods for determining the condition of structures are needed to identify when the useful life has expired or other maintenance is needed. Due to its unique alloy blend, high-performance steel (HPS) has been shown to have improved weldability, weathering capabilities, and fracture toughness than conventional structural steels. Since the development of HPS in the mid-1990s, numerous bridges using HPS girders have been constructed, and many have been economically built. The East 12th Street Bridge, which replaced a deteriorated box girder bridge, is Iowa’s first bridge constructed using HPS girders. The new structure is a two-span bridge that crosses I-235 in Des Moines, Iowa, providing one lane of traffic in each direction. A remote, continuous, fiber-optic based structural health monitoring (SHM) system for the bridge was developed using off-the-shelf technologies. In the system, sensors strategically located on the bridge collect raw strain data and then transfer the data via wireless communication to a gateway system at a nearby secure facility. The data are integrated and converted to text files before being uploaded automatically to a website that provides live strain data and a live video stream. A data storage/processing system at the Bridge Engineering Center in Ames, Iowa, permanently stores and processes the data files. Several processes are performed to check the overall system’s operation, eliminate temperature effects from the complete strain record, compute the global behavior of the bridge, and count strain cycles at the various sensor locations.

ICN Insider, August-September 2011

The ICN, a state agency, is the country’s premier fiber-optic Network, committed to continued enhancement of distance learning and providing Iowans with convenient, equal access to education, government, and healthcare. This newsletter is produced monthly by the ICN of all the programs and activities of this department.

ICN Insider, December 2010

The ICN, a state agency, is the country’s premier fiber-optic Network, committed to continued enhancement of distance learning and providing Iowans with convenient, equal access to education, government, and healthcare. This newsletter is produced monthly by the ICN of all the programs and activities of this department.

ICN Insider, February 2011

The ICN, a state agency, is the country’s premier fiber-optic Network, committed to continued enhancement of distance learning and providing Iowans with convenient, equal access to education, government, and healthcare. This newsletter is produced monthly by the ICN of all the programs and activities of this department.

ICN Insider, February 2012

The ICN, a state agency, is the country’s premier fiber-optic Network, committed to continued enhancement of distance learning and providing Iowans with convenient, equal access to education, government, and healthcare. This newsletter is produced monthly by the ICN of all the programs and activities of this department.

ICN Insider, October 2010

The ICN, a state agency, is the country’s premier fiber-optic Network, committed to continued enhancement of distance learning and providing Iowans with convenient, equal access to education, government, and healthcare. This newsletter is produced monthly by the ICN of all the programs and activities of this department.

ICN Insider, January 2011

The ICN, a state agency, is the country’s premier fiber-optic Network, committed to continued enhancement of distance learning and providing Iowans with convenient, equal access to education, government, and healthcare. This newsletter is produced monthly by the ICN of all the programs and activities of this department.

ICN Insider, January-February 2013

The ICN, a state agency, is the country’s premier fiber-optic Network, committed to continued enhancement of distance learning and providing Iowans with convenient, equal access to education, government, and healthcare. This newsletter is produced monthly by the ICN of all the programs and activities of this department.

ICN Insider, January-February 2014

The ICN, a state agency, is the country’s premier fiber-optic Network, committed to continued enhancement of distance learning and providing Iowans with convenient, equal access to education, government, and healthcare. This newsletter is produced monthly by the ICN of all the programs and activities of this department.

ICN Insider, January 2012

The ICN, a state agency, is the country’s premier fiber-optic Network, committed to continued enhancement of distance learning and providing Iowans with convenient, equal access to education, government, and healthcare. This newsletter is produced monthly by the ICN of all the programs and activities of this department.

ICN Insider, July-August 2013

The ICN, a state agency, is the country’s premier fiber-optic Network, committed to continued enhancement of distance learning and providing Iowans with convenient, equal access to education, government, and healthcare. This newsletter is produced monthly by the ICN of all the programs and activities of this department.

ICN Insider, July-August 2014

The ICN, a state agency, is the country’s premier fiber-optic Network, committed to continued enhancement of distance learning and providing Iowans with convenient, equal access to education, government, and healthcare. This newsletter is produced monthly by the ICN of all the programs and activities of this department.

ICN Insider, July-August 2010

The ICN, a state agency, is the country’s premier fiber-optic Network, committed to continued enhancement of distance learning and providing Iowans with convenient, equal access to education, government, and healthcare. This newsletter is produced monthly by the ICN of all the programs and activities of this department.

ICN Insider, July-August 2012

The ICN, a state agency, is the country’s premier fiber-optic Network, committed to continued enhancement of distance learning and providing Iowans with convenient, equal access to education, government, and healthcare. This newsletter is produced monthly by the ICN of all the programs and activities of this department.