Introduction of stresses due to shoring

[marc.rogue]

I have been analyzing the effects of shoring specifically in prestress members. Some systems call for crown, an additional push of the member upwards are erection. This is usually accomplished by pushing the piece at the middle of the span with a post shore up to the specified crown.I am wondering can this simply be taken as a point load acting at the bottom of the beam or is there a more robust way to go about analyzing this.

Mind you this has an effect in internal stresses and camber. Additional stress is being provided to the bottom of the beam which further compresses the bottom. Also a stress analysis is done and all allowable stresses are met.

 

[r13]

For already hardened prestress member, you can push it up, but only to an extent to negate the effect of member self weight, since the weight is already there, and the strands have lengthened/relaxed accordingly. But I would push at more points than one to assure the deformation of push up agrees with the deflection shape due to self weight. After all, you will need to restress before un-shore then.