Banner for LabNotes
From Lab Notes
Contact Information
Forest Products Laboratory
One Gifford Pinchot Drive
Madison, WI 53726-2398
Phone: (608) 231-9200
Fax: (608) 231-9592


You are here: FPL Home  / Information Products & Services  / Publications

Requested Product

Title: Ultrasonic Inspection of Large Bridge Timbers

Source: Forest Prod. J. 52(9):88-95.

Author(s)Emerson, Pollock, McLean, Fridley, Pellerin, Ross

Publication Year: 2002  View PDF »

Category: Journal Articles

Abstract: Timber bridges are susceptible to attack from wood decay fungi. Significant losses in wood material properties are associated with increasing decay. Therefore, timber bridges must be monitored for decay in order to maintain structural safety. Historically, decay has been identifiable in large timber structural elements only after significant losses in structural performance have occurred. Recent developments in nondestructive evaluation techniques have focused on identifying decay before large strength losses occur. For this study, an ultrasonic inspection technique was developed for identifying incipient decay in large bridge timbers. Two large bridge timbers were nondestructively evaluated via ultrasonic inspection. Relative ultrasonic wave velocity measurements were used to identify locations of moderate to advanced decay. The timbers were then dissected and the predicted internal condition compared favorably to the actual internal condition. Specimens suspected of containing incipient decay were removed from one of the bridge timbers and subjected to further ultrasonic testing followed by physical testing. The objective was to develop an ultrasonic inspection technique that can be used to identify the presence of decay before significant losses in physical properties occur. The developed technique involved transmitting ultrasonic waves through the specimen and measuring characteristics of the received signal. The characteristics of the received signal were then correlated with the physical properties of the specimen. Two main signal parameters can be used to identify decay. Wave velocity can be used to identify the presence of moderate to advanced decay but cannot be used to identify incipient decay. Relative ultrasonic wave attenuation can be used to identify incipient through advanced decay. The ability to identify incipient decay will allow for corrective action to take place before structural safety is compromised and before expensive structural repairs are required.

File size: 400 kb(s)

Date posted: 04/05/2010
Current FPL Scientist associated with this product
Ross, Robert J.
Supervisory Research Gen. Engineer

Additional items that might interest you
View the video celebrating FPL's 100 years of public service in 2010, from the producers of the Greatest Good....view

Research Highlights from FPL....view

Termite Eradication: A search for the Holy Grail.... view

Moisture Management in Residential Construction Series videos...view

Wood Floor Systems in Residential Construction Series videos....view
- FPL's Mission and Strategic Plan -

FPL's mission is to identify and conduct innovative wood and fiber utilization research that contributes to conservation and productivity of the forest resource, thereby sustaining forests, the economy, and quality of life. ... ..more »

- FPL Research Emphasis Areas -
Advanced Composites

As an integral part of the FPL mission, we improve the long-term sustainability of our Nation's forests by creating valuable composite products from biobased materials ... ..more »

Advanced Structures

The FPL has been in the forefront of wood-frame housing research since 1910 and has long been recognized as a world leader in such housing-related areas as engineered wood ... ..more »

Forest Biorefinery

We all know the compelling reasons that the United States needs to reduce its dependence on fossil fuels. Historically, the greatest increases in energy demand have been for transportation fuels ... ..more »


A leader in wood products research for over a century, the FPL is positioning itself to become the lead Federal research facility for the application of nanotechnology in forest products ... more »

Woody Biomass Utilization

Forests in the United States contain a substantial amount of small-diameter, overstocked, and underutilized material.FPL research projects are exploring the potential of the small-diameter ... ..more »