LOAD CAPACITY OF JACK-ARCH BRIDGES. FINAL REPORT

A 76-year-old jack-arch bridge was tested to failure to obtain information on load capacity and the degree of composite action between the steel beams and concrete deck. This work was started because despite the good condition of the majority of the 1300 jack-arch bridges in New York, load-rating estimates indicate that they are inadequate to support moderm highway traffic. The most likely explanation for the observed performance of these bridges is that they are resisting loads in ways not considered in design or load-rating calculations. Although these bridges have no mechanical shear-transfer devices to assure composite action, it was suspected that chemical bond and friction were sufficient to provide the observed enhancement in load capacity. The 39-ft-span test structure consisted of six 24-in. deep I-beams spaced at 36 in. Instrumentation consisted of electrical-resistance strain gages on both flanges at midspan, end-rotation measurements devices at the ends of two beams, and deflectometers at midspan. The bridge was loaded to produce a 6-ft region of constant moment at the center of the span. Loads were applied through hydraulic jacks reacting against grouted anchors beneath the structure. Based on the results of this test and an earlier test of a similar structure, it is concluded that full composite action may be assumed in load-rating estimates of jack-arch bridges. Although significant restraint of end rotation was also observed in both tests, a generalization of this restraint to other structures is not possible.

• Corporate Authors:

  New York State Department of Transportation

  Engineering Research and Development Bureau, 1220 Washington Avenue
  Albany, NY  United States  12232

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Beal, D B
• Publication Date: 1985-12

Media Info

• Pagination: 39 p.

Subject/Index Terms

• TRT Terms: Arch bridges; Bearing capacity; Bridge decks; Chemical bond; Concrete; Friction; I beams; Load tests; Mechanical tests
• Uncontrolled Terms: Destructive testing; Steel beams
• Subject Areas: Bridges and other structures; Design; Highways; I24: Design of Bridges and Retaining Walls;

Filing Info

• Accession Number: 00458346
• Record Type: Publication
• Source Agency: Federal Highway Administration
• Report/Paper Numbers: FHWA/NY/RR-85/129, FCP 45K2-024
• Files: TRIS, USDOT, STATEDOT
• Created Date: Sep 30 1986 12:00AM