Hello,
I am trying to use LEAP Steel for a high skew steel bridge.
When checking the automatically generated the concrete deck self-weight, there is an issue that I do not understand.
The self weight of the concrete deck seems to be calculated with the skewed length between the girders, and not the perpendicular distance.
I checked the same 3-span bridge with and without skewed support and the concrete self-weight generated by the software are giving me different values, which does not make any sense to me since the bridges are the same width, so they should have the same overall self-weight on them. Has anyone been able to resolve this issue? There must be a setting that I am not indicating properly
Bridge 1 - Straight supports:
Perpendicular distance between girders: 6.5 ft
Skew: 0 degrees
Distance between girder (along skew): 6.5 ft (6.5ft / cos 0 deg)
Deck thickness: 7.0 in + 0.5 in sacrificial wearing surface + 2 in haunch.
LEAP generated self-weight of slab for an interior beam = 0.5685 kip/ft (150 pcf x 6.5 ft x 7 in/12 ft/in = 0.5688 kip/ft OK)
Bridge 2 - Skewed supports (same bridge (same design file but changed the skew)
Skew: 54 degrees
Distance between girder (along skew): 11.06 ft (6.5ft / cos 54 deg = 11.06 ft OK)
LEAP generated self-weight of slab for an interior beam = 0.9674 kip/ft (150 pcf x 11.06 ft (???) x 7 in/12 ft/in = 0.9678 kip/ft ????)
I do not understand why these two bridge do not have the same slab self-weight on them even though the overall surface of the deck will be the same. This ends up being a very significant difference and makes me think I am not modeling something properly.
Any input would be greatly appreciated. I would assume someone has gone through this already and has found the solution!
Thank you in advance
Emilie
in Leap Bridge Steel the section cut is made perpendicular to the alignment and not along the skew and that's the reason the program is showing different slab self-weight on them even though the overall surface of the deck will be the same.
Hello Vinay,
Thanks for your answer. I am afraid I still don't understand what is going on. If the section cut is made perpendicular to the alignment, then the self-weight of the concrete on the girder should be the same with skewed and non-skewed supports as long as the perpendicular distance between the girders are the same (which they are). If I add up all the deck self-weight on the bridge with the skewed support it is much greater than the deck self-weight on the bridge with the straight support, even though the overall deck surface is the same.
I also tried modeling a bridge with a skewed support on one end and a straight support at the other and I get the same discrepancy as before (that is the self-weight of the deck is greater on the skewed end than at the straight end, even though the girders are straight and the perpendicular distance between them is the same).
Is there someone I can send my file to at Bentley that can help me out with this?
Thanks!
You can email me the file "vinay,mysore@bentley.com"
vinay.Mysore@bentley.com