Post tensioned Transfer Girder
Post tensioned Transfer Girder
(OP)
Folks,
I am looking for some help and guidance in the design of a 58 foot long PT transfer girder carrying 4 floors. Are there any rules of thumb for sizing, examples for design that might be useful.
I don't want to plug numbers into a program without understanding the design procedures and pitfalls.
Thanks
I am looking for some help and guidance in the design of a 58 foot long PT transfer girder carrying 4 floors. Are there any rules of thumb for sizing, examples for design that might be useful.
I don't want to plug numbers into a program without understanding the design procedures and pitfalls.
Thanks






RE: Post tensioned Transfer Girder
RE: Post tensioned Transfer Girder
RE: Post tensioned Transfer Girder
RE: Post tensioned Transfer Girder
Like others said, you have to do "stage stressing" for this transfer beam. The reason is not to apply too much post-tensioning force when you do not have that much dead load to balance. You best dead load balance is around 60% to 80% of dead load. If you design unbonded tendons, you can specify percentage of tendons to be stress at each stage. If you decided to use bonded tendons, it is better to stress one tendon to 100% at a time rather than stress 50 % of total force. Typically, you can specify two stage stressing for a 4-floor girder.
In addition, you may want to use bonded tendons for this transfer girders because ACI 318 allows you to design PT force using much higher steel stresses. If you decided to use bonded tendons, you may want to check PT supplier's catalog for sizes of the anchorages and make sure they will fit in your beam's end section. Your end drap may be affected accordingly, too.
RE: Post tensioned Transfer Girder
The best advice that I have received in my career was when I was a couple of years out of school and the owner of the company that I worked for told me that you need to be aware when something looks funny or overly complex because you will normally have something laid out wrong. It has always amazed me have effective this simple advice is. I recommend that you look for a different solution that doesn't require a 58' transfer beam.
RE: Post tensioned Transfer Girder
Also, deflections are typically limited to L/1660