Rotation of a Wall Type Abutments
Rotation of a Wall Type Abutments
(OP)
Question-1:
Wall type abutments will be backfilled before the superstructure will be erected. Any deflection of the wall will decrease the expansion joint opening. I need to know how much the abutment will rotate due to the backfill, and then I can take that into account when sizing the expansion joint. I need the geotechs to tell me how much the abutment will rotate due to the backfill. The Wall abutment is about 30 ft. heigh.
Question-2:
After the superstructure is erected (and the bridge loads are on the abutment), I need to know if there is any long term settlement that would cause the abutment to rotate, and if there is any additional rotation due to a live load surcharge on the backfill. This information would be used to verify the expansion joint opening and would also be used to size the bridge bearings per the project scope of work.
Wall type abutments will be backfilled before the superstructure will be erected. Any deflection of the wall will decrease the expansion joint opening. I need to know how much the abutment will rotate due to the backfill, and then I can take that into account when sizing the expansion joint. I need the geotechs to tell me how much the abutment will rotate due to the backfill. The Wall abutment is about 30 ft. heigh.
Question-2:
After the superstructure is erected (and the bridge loads are on the abutment), I need to know if there is any long term settlement that would cause the abutment to rotate, and if there is any additional rotation due to a live load surcharge on the backfill. This information would be used to verify the expansion joint opening and would also be used to size the bridge bearings per the project scope of work.





RE: Rotation of a Wall Type Abutments
How much a wall will rotate depands on a number of factors - thickness of the wall and fixity at the base, how much or how little the soil against the wall is compacted - normally you keep big rollers away from the wall at least 5 ft. (heavy compaction against the wall can induce large residual horizontal stresses that have a ko value > the normally accepted 0.5.
Long term settlement causing the wall to rotate - what are the supporting soils? All soils creep. How much will the toe pressure be? A lot of factors, as we indicated go into this - if you are trying to play millimeters, then you might have a better chance in the lottery.