In April of 2008, the Federal Highway Administration (FHWA) launched the Long Term Bridge Performance (LTBP) program. The program was established to collect scientific quality data from a number of bridges across the nation over a period of 20 years. The data will be used to provide a better picture of bridge health and structural performance. Utah Department of Transportation (UDOT) structure number 1F 205, located 2.4 km (1.5 mi) west of Perry, Utah, was selected as one of the LTBP pilot bridges (this bridge will also be referred to as the Cannery Street Overpass).
UDOT performs regular maintenance on this bridge and in April of 2011 they began a rehabilitation project over a 13-km (8-mi) section of I-15 that included the Cannery Street Overpass. The main purpose of this rehabilitation was to improve pavement conditions. As part of this work, in the fall of 2011 UDOT removed all of the asphalt from the bridge deck, performed deck repairs, and placed a new asphalt layer. A unique opportunity presented itself to better understand the relationship between the mass and resonant vibration frequencies of the structure. This relationship is understood by (omega_n)^2=k/m, where omega_n=resonant frequency; k=stiffness; and m=mass. A decrease in mass should yield an increase in resonant frequency.
Dynamic testing was done on the bridge to obtain its resonant frequencies. This testing included measuring the velocity response of the structure at different points on the bridge due to ambient vibrations (mainly from traffic). Three tests were performed before, during, and after UDOT's scheduled maintenance. These testing states include: State 1. Original asphalt on bridge deck State 2. No asphalt on bridge deck State 3. New asphalt on bridge deck These three states represent three different mass states of the bridge. The original asphalt layer was substantially heavier than the new asphalt layer. The data obtained from all three tests was processed in order to extract modal properties of the bridge. The changes in modal properties were analyzed and the results of the testing proved to be insightful at defining the relationship between mass and resonant frequency.
| Identifer | oai:union.ndltd.org:UTAHS/oai:digitalcommons.usu.edu:etd-2162 |
| Date | 01 May 2011 |
| Creators | Dean, Michael W. |
| Publisher | DigitalCommons@USU |
| Source Sets | Utah State University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | All Graduate Theses and Dissertations |
| Rights | Copyright for this work is held by the author. Transmission or reproduction of materials protected by copyright beyond that allowed by fair use requires the written permission of the copyright owners. Works not in the public domain cannot be commercially exploited without permission of the copyright owner. Responsibility for any use rests exclusively with the user. For more information contact Andrew Wesolek (andrew.wesolek@usu.edu). |
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