Harped strands for slab


2 replies [Last post]
Jimmy Chen
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Joined: 06/18/2012

In library, the harped strands are setup for most of girders except for the slab type girders. I manually specified a few individual strands as harped for my 1'-0" solid slab girders and it run very well. I cannot see any reason the harped strands cannot be allowed in slab girder design.

However in Library, all harped strands were specified to locate at a minimum distance of 4" to girder bottom or top. Is this value (4" minimum) from BDM 5.1.3c, which said "harped strands are placed in a single bundle with the centroid 4? above the bottom of
the girder. "? Can I specify individual strands at a distance of 2" from the bottom (at middle) or top(at ends) of girder? Is there any special limits/requirements I did not see? Do I have to bundle all harped strands together?

Thank you,
Jimmy

Jimmy Chen

Rick Brice
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Joined: 06/22/2010
Harped Strands

Jimmy,
 
I’m uncertain if your questions are asking for deviations from WSDOT standard practice or if you are inquiring about the capabilities of the PGSuper software. I cannot approve any deviations from WSDOT practice, especially in a public software support forum. My responses address only the capabilities and usage of the PGSuper software.
 
It is WSDOT’s practice to use only straight strands in slab type girders. End stresses are controlled with debonding. You may be able to get harped strands to work from an analytical point of view; however you may want to check with potential fabricators as to feasibility.
 
The 4” minimum distance from BDM 5.1.3c is based on the minimum capability of local fabricators. In PGSuper, you can change these minimums in the Girder Library Entry for the girder in question. The minimums apply to all harped strands and define the minimum distance from the top and bottom of the girder to the highest and lowest row in the gird of harped strands. The harped strand adjustments in the Girder Editing window (the window used to edit the actual girder in the bridge, not the library definition) are used to precisely position the harped strands vertically at the ends and harping points.
 
The only requirement for the placement of harped strand locations in PGSuper is that the strands must be located within the boundary of the cross section of the girder.
 
You are not required to bundle all harped strands together in PGSuper. Simply define each harped strands, at the harping point, at a different location.
 
Respectfully,
 
Richard Brice, PE
Software Applications Engineer
WSDOT Bridge and Structures Office

Jimmy Chen
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Joined: 06/18/2012
I realized the question was

I realized the question was about deviations from WSDOT requirements, not questioning the PGSuper's capabilities. Your input helped me get what I want. Thank you so much.

Jimmy Chen