SAFETY AND SOUNDNESS OF SUBMERGED TIMBER BRIDGE PILING

Despite a recent underwater inspection of the piling, an unanticipated failure occurred to a timber supported bridge at Denton, Maryland in early 1976. The underwater inspection had indicated reasonable soundness of the timber but later laboratory tests indicated substantial reduction in material strength during the life of the piling. This project deals with the development of a nondestructive testing technique for determining the in-place residual strength of timber piling due to damage to the wood microstructure that causes loss in strength and density. The testing technique employed is the ultrasonic wave propagation method. Above and under water equipment were developed and the testing procedure and limitations are presented. A large number of new piles and old piles from four different bridges in the State of Maryland were first tested by the equipment developed and their dynamic modulus of elasticity determined, followed by testing to failure for residual strength determination. In addition, small specimens were cut from old and new piles and the mechanical properties determined for a large number of variables such as unit weight, moisture content, effect of treatment and the direction of grain. From the testing program correlation curves were developed between the nondestructive testing results and the residual strength of the timber piles. The results to date provide an adequate inspection procedure to determine if damage is occurring or has occurred and to what extent. A quantitative determination of the residual strength of timber piles in service will enable the engineer to make appropriate judgments as to the ability of the pile to further support the loads imposed upon it. The results presented in this interim report are a summary of testing performed up to April 1982. Additional testing is underway and will be presented in the final report. (FHWA)

• Corporate Authors:

  University of Maryland, College Park

  Department of Civil and Environmental Engineering
  College Park, MD  United States  20742

  Maryland Department of Transportation

  State Highway Administration, 707 N Calvert Street
  Baltimore, MD  United States  21202

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Aggour, M S
  • Ragab, A
• Publication Date: 1982-6

Media Info

• Pagination: 421 p.

Subject/Index Terms

• TRT Terms: Loss and damage; Modulus of elasticity; Nondestructive tests; Residual strength; Safety; Soundness test; Support piles; Timber; Ultrasonic tests; Underwater construction; Underwater structures; Wooden bridges
• Old TRIS Terms: Soundness; Timber piles
• Subject Areas: Bridges and other structures; Design; Highways; Safety and Human Factors; I24: Design of Bridges and Retaining Walls;

Filing Info

• Accession Number: 00376397
• Record Type: Publication
• Report/Paper Numbers: FHWA/MD-82/10 Intrm Rpt.
• Contract Numbers: AWO82-231-046
• Files: TRIS, USDOT, STATEDOT
• Created Date: Aug 30 1983 12:00AM