A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
The South Dakota Department of Transportation has experienced problems with rotation of sill type bridge abutments resulting in abutments backwalls jamming against the ends of girders and bridge decks. A sill tieback system to prevent displacement and rotation of bridge abutments has been designed for use in new construction and abutment retrofitting. The tieback system consists of a series of drilled-in concrete anchors placed behind an abutment backwall. Sleeves are cast in the anchors and abutment backwall to allow threaded rods to be passed through and locked off at a predetermined tension. In an earlier project, software was developed defining tieback system design parameters using finite element analysis. This software, called BART, uses soil and foundation survey information and bridge design parameters as input. Because the design parameters produced by the software are theoretical, there was a desire to verify its accuracy. This project was initiated to monitor actual loads and movements on newly constructed sill tieback systems for comparison of predictions from the design program. The research results indicated that for the structures tested, adequate correlation could be seen. In addition, there was interest in developing a simple method for monitoring tension in each tie rod as an integrity test of sill tieback systems. A method was established whereby measuring the torque of the lock-off nut with a torque wrench, the load can be estimated by comparing the values obtained with a torque/load chart included in this report.
The South Dakota Department of Transportation has experienced problems with rotation of sill type bridge abutments resulting in abutments backwalls jamming against the ends of girders and bridge decks. A sill tieback system to prevent displacement and rotation of bridge abutments has been designed for use in new construction and abutment retrofitting. The tieback system consists of a series of drilled-in concrete anchors placed behind an abutment backwall. Sleeves are cast in the anchors and abutment backwall to allow threaded rods to be passed through and locked off at a predetermined tension. In an earlier project, software was developed defining tieback system design parameters using finite element analysis. This software, called BART, uses soil and foundation survey information and bridge design parameters as input. Because the design parameters produced by the software are theoretical, there was a desire to verify its accuracy. This project was initiated to monitor actual loads and movements on newly constructed sill tieback systems for comparison of predictions from the design program. The research results indicated that for the structures tested, adequate correlation could be seen. In addition, there was interest in developing a simple method for monitoring tension in each tie rod as an integrity test of sill tieback systems. A method was established whereby measuring the torque of the lock-off nut with a torque wrench, the load can be estimated by comparing the values obtained with a torque/load chart included in this report.
Field Performance of Abutment Tiebacks
1996
94 pages
Report
No indication
English
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