INSIDE THE DOT
South Dakota Department of Transportation
Field Performance of Abutment Tiebacks
Paul Orth, SDDOT
The South Dakota DOT uses a tieback system to prevent displacement and rotation of bridge end abutments. The department has sponsored and is sponsoring research to develop design software to define design parameters for the tieback system. The designs produced by the software are theoretical, and have not been verified in field measurements.
1 To determine if actual tieback forces occurring in the structure abutment tendons during tieback testing and at various post construction intervals agree with theoretical design parameters.
2 During the study, structural parameters in the drilled shaft anchor piles such as tilt or displacement should also be measured.
3 Determine if a simple method of checking post construction tension on tendons is possible.
1 A minimum of three sites will be selected from the construction program for study. Testing will proceed on an “as available for construction basis”.
2 Instrument all tendons of one structure per site location for force analysis.
3 Instrument drilled shaft anchors to measure displacement at same location.
4 Measure abutment movements by tilt analysis or by direct displacement method.
5 Determine if measurement of torque on tendon head nut with a torque wrench can be a valid method of monitoring post construction tendon tension.
6 Following a measurement period of one year a report will be written that summarizes the progress.
7 The above procedure will be used on three structures as they are available for construction. A final report will be written summarizing the entire project. Anchor parameter data collection will continue throughout the entire project and the data wi
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