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Title: Estimating bridge stiffness using a forced-vibration technique for timber bridge health monitoring

Source: Proceedings : NDE Conference on Civil Engineering : a joint conference of the 7th Structural Materials Technology: NDE/NDT for Highways and Bridges and the 6th International Symposium on NDT in Civil Engineering, 2006 August 14-18, St. Louis, MO. Columbus

Author(s)Wacker, James P.; Wang, Xiping; Brashaw, Brian; Ross, Robert J.

Publication Year: 2006  View PDF »

Category: Journal Articles

Abstract: This paper describes an effort to refine a global dynamic testing technique for evaluating the overall stiffness of timber bridge superstructures. A forced vibration method was used to measure the frequency response of several simple-span, sawn timber beam (with plank deck) bridges located in St. Louis County, Minnesota. Static load deflections were also measured to establish the benchmark stiffness level for each bridge superstructure. Analytical models based upon simple beam and plate theory were utilized to characterize the relationship between the 1st bending mode frequency and the stiffness of the bridge superstructure. The results indicate that forced-vibration methods have potential for quickly assessing timber bridge superstructure stiffness. However, improvements must be made to the measurement system to correctly identify the 1st bending mode frequency of the field bridges. The beam theory model matched the physics of the single-span, timber beam superstructures better than plate theory. This global vibration technique has potential benefits for routine inspections and long-term health monitoring of timber bridge superstructures.

Keywords: Dynamic testing, service life, wood deterioration, deterioration, nondestructive testing, vibration, wooden bridges, inspection, bridges, frequency response, bending strength, simple beam theory, bending mode frequency, stiffness, timber bridges

File size: 275 kb(s)

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RITS Product ID: 23953
Current FPL Scientists associated with this product (listed alphabetically)
Ross, Robert J.
Supervisory Research Gen. Engineer
Wacker, James P.
Research General Engineer
Wang, Xiping
Research Forest Products Technologist

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