Location

Brunswick, ME

Start Date

1-1-1997 12:00 AM

Description

The effective life of timber bridges is often shortened by decay of timber components and failure of timber connections. Consequently, periodic inspections must be carried out to identify potential problems. Reliable methods for in-situ assessment of the strength and degradation rate in terms of strength loss over a period of time are essential for maintenance and rehabilitation of wooden bridges. A nondestructive technique such as ultrasonic measurement and testing has been found to be more accurate than the conventional practice of visual inspection for assessing the condition of wooden members. Ultrasonic measurements have shown considerable promise in determining the stiffness and strength of wood members by identifying the presence of defects such as knots and decay [1,2,3]. Experimental results have shown significant differences between the velocities of ultrasonic signals in defect-free areas and areas with knots, decays, and other localized defects [4]. Halabe et al. [5,6] has shown that frequency domain signal amplitude and wave attenuation measurements, when used in conjunction with time domain velocity measurements, can be much more accurate and reliable than simply using velocity measurements in predicting stiffness and condition of wood. Use of simple parameters such as area under FFT amplitude plots or power spectral density plots can greatly simplify comparison of various signals in the field.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

16B

Chapter

Chapter 6: Material Properties

Section

Construction Materials (Concrete, Timber)

Pages

1783-1790

DOI

10.1007/978-1-4615-5947-4_233

Language

en

File Format

application/pdf

Share

COinS
 
Jan 1st, 12:00 AM

Development and Field-Testing of a Hand-Held Ultrasonic Monitoring Device

Brunswick, ME

The effective life of timber bridges is often shortened by decay of timber components and failure of timber connections. Consequently, periodic inspections must be carried out to identify potential problems. Reliable methods for in-situ assessment of the strength and degradation rate in terms of strength loss over a period of time are essential for maintenance and rehabilitation of wooden bridges. A nondestructive technique such as ultrasonic measurement and testing has been found to be more accurate than the conventional practice of visual inspection for assessing the condition of wooden members. Ultrasonic measurements have shown considerable promise in determining the stiffness and strength of wood members by identifying the presence of defects such as knots and decay [1,2,3]. Experimental results have shown significant differences between the velocities of ultrasonic signals in defect-free areas and areas with knots, decays, and other localized defects [4]. Halabe et al. [5,6] has shown that frequency domain signal amplitude and wave attenuation measurements, when used in conjunction with time domain velocity measurements, can be much more accurate and reliable than simply using velocity measurements in predicting stiffness and condition of wood. Use of simple parameters such as area under FFT amplitude plots or power spectral density plots can greatly simplify comparison of various signals in the field.