Thanks for your input! In that particular beam, it does need all four top bars for flexural strength. But, being prestressed, sometimes the amount of top steel is controlled by transfer stresses. So, for standardization, that might mean adding two more top #9 bars. Then, it seems I can pretend...
9.7.6.4.1 states that the requirements apply "where longitudinal compression reinforcement is required". What exactly does that mean? If a beam works without the top bars considered in the analysis, then.. confinement is not required? Even if those bars, in reality, are stressed substantially...
The method I've settled on is to apply one LLR factor for flexure and shear design. However, for punching shear and local effects (say point loads), I take the tributary area and respective LLR for that load only.
It simply doesnt make sense that having two concentrated loads on opposite ends...
Yes I've seen this as well. I believe we are one of few designers who try to account for torsion within the precast industry. The apparent lack of issues with our competitors who don't, though, seems to imply their logic is sound and the torsion is being resolved thru other mechanisms than...
Any other thoughts on this?
How it's detailed now, the dap joint is grouted all around, so the torsion would be resolved "at" the dap via a compression couple on either side of the beam cross section. In theory then, this is similar to a fixed end beam. It shouldn't allow significant torsion to...
Yes, its significant enough to cause decompression in the bearing pad - something like 120k*ft of torsion and 140k reaction. Senior proposed using a welded connection at the top of the nib and a mechanical connection at the bottom to create a couple and remove/reduce the bearing eccentricity...
How would you accomplish that? Not sure I understand.
In other cases where the "dapping beam" has torsion, I am using connections from the beam to the precast slabs to remove it; therefore the beam itself does not experience torsion. However, there are a few cases where it is not possible use...
I have a precast, prestressed inverted tee beam with significant torsion. It needs to dap onto another beam to receive it. Does torsional reinforcing need to extend into the nib? I believe it should, however my senior has told me otherwise - the crack will form after the re-entrant corner, so...
Hello, first time posting but look here often. I'm getting into some debates in the office on handling LLR in precast structures. There's a few different concerns here so I think I'll start with the most basic: See the attached image of the precast floor plan, and an overlay of a joist framing...
