stevey
Structural
- Feb 19, 2003
- 11
Hello all -
We've run into a slight problem on a bridge job. The contractor mis-read a P/T note on our cross beam plan. Our beam had 4 rows of duct runs (4 duct in each row - 16 ducts total, with the Pj for each row given 21,,092 kN. The contractor read this as 21,092 kN total for all rows, and sized the ducts accordingly. Our reviewer missed this on the shop drawings. One row of ducts (4 total) was to be left empty for later use for a proposed bridge widening.
Since we fortunately have more ducts to work with, the idea is to stuff the ducts with more strands (go from 12 each to 24), which will reduce the desired void from 2.5 minimum to slightly less than 2.0. I'm guessing that the min void area is for constructability, but want to make sure I'm not getting myself in trouble by stuffing more strands in the ducts. We can adjust our grout a bit for easier flow, and fortunately, the strand trajectories are simple parabolic drapes. Is reducing the void ratio an OK thing, or should I reduce the strands and use my empty (widening) ducts?
Thanks
Steve R. Yates
City of Portland Oregon
Office of Transportation Engineering
We've run into a slight problem on a bridge job. The contractor mis-read a P/T note on our cross beam plan. Our beam had 4 rows of duct runs (4 duct in each row - 16 ducts total, with the Pj for each row given 21,,092 kN. The contractor read this as 21,092 kN total for all rows, and sized the ducts accordingly. Our reviewer missed this on the shop drawings. One row of ducts (4 total) was to be left empty for later use for a proposed bridge widening.
Since we fortunately have more ducts to work with, the idea is to stuff the ducts with more strands (go from 12 each to 24), which will reduce the desired void from 2.5 minimum to slightly less than 2.0. I'm guessing that the min void area is for constructability, but want to make sure I'm not getting myself in trouble by stuffing more strands in the ducts. We can adjust our grout a bit for easier flow, and fortunately, the strand trajectories are simple parabolic drapes. Is reducing the void ratio an OK thing, or should I reduce the strands and use my empty (widening) ducts?
Thanks
Steve R. Yates
City of Portland Oregon
Office of Transportation Engineering
