Few questions on ConSpan

[engny101]

our company bought conspan program to design prestress concrete beams. I have few question about the software. I will really appreciate if someone who have used Conspan before can answer these questions.
1. I have a curve alignment. with straight girders. This will result in varying Overhangs. How conspan will handle this.
I have few more questions.

 

[abusementpark]

CONPSAN cannot do variable overhangs, at least it couldn't when I was using it.

For the girders that are to the outside of the curve, the maximum overhang will occur at center span. For this case, I just simply took that maximum as the overhang for the whole girder and it is conservative. I looked a few different cases and found that this was the best way to do it. You are increasing the section properties of that girder since it is composite construction, but you will find that the additional area for live load to be distributed will have a greater impact on the stresses. I also looked at a case where I just took the average of the overhand as the constant value and manually put back the extra dead load I had taken off back on as an external load. The aforementioned case governed.

For the girders that are to the inside of the curve, you have the maximum overhang occurring at the beginning of the span and the minimum occurring at the midspan. For this, I just used the average value. Intuitively this seemed fine, since the portion of the beam where the maximum was occurring have a minimal effect on the stress and since I was putting extra overhang than was really there at the most critical portion of beam (midspan). Anyways, you will find that the outside exterior girder will control anyways and you most likely will use that strand pattern for the whole set of girders.

Despite this shortcoming, CONSPAN is a pretty good program. I was able to verify a lot of the results by hand. One thing you may want to look at is how they calculate their prestress loss. I was able to match their losses, but they added some gains back in based on some theory that I wasn't completely familiar with. Also, their auto-design never gets the best strand pattern. It will not be able to find a working design sometimes, but you will be able to tweak to make it work, if you have a good understanding of how prestressed concrete works. It just gives you a starting point.

Good luck!

 

[engny101]

Thanks for the quick reply. I really appreciate it.
ver. 7.00 of the conspan has two design options.
Deck with constant width & for flared girder (this is added feature for this version)
In this option, we can put the alignment geometry which can be curve or tangent. I want to know
1. Can we use flared girder option for constant deck width (somehow trick the program??). I can then give the curve geometry for the alingment & also the fascia (I am not sure) & then put the straight girder somehow with some bearings. This will make the model with variable overhang & design accordingly. Any help or advice is appreciated.
2. Any known problems with conspan? I heard about issue with Distribution factor (most probably for external girder) & equivalent deck width.
3. Any input file or sample run available showing how the loads are calculated & input in the program. If yes, please upload it if possible.
thanks for all the help and advice.
thanks
nadeem

 

[engny101]

abusement park,
one more question for you.
What is the advantage of using CONSPAN if we are putting the max. or average OH. It is what we normally use for one line girder programm such as PENNDOT STLRFD or other similar projects.
Thanks for the answer.