Rebar Lap Splice Location - Located at midspan/high stress (critical location)

[hssbrian]

Hello Everyone,

I was asked to review certain drawings for a construction firm of a single story house that they use as a standard to build. I noticed that the drawings do not consider or even take into account development lengths, splices or their locations... Even though they say they have been building these houses for 10 years they have no consideration of this matter and when I asked them about it they said that each construction team does it at their discretion. The building is 20.26mx10.41m and they use premanufactured beams (6m) and grade beams that span to isolated footing at 4.13m oc and 3m oc.

As is my understanding beams would have to be spliced at their bottom near columns and at their top near midspan. For grade beams it would be the opossite.

Because they use a premanufactured beam they lap splice will coincide for both top and bottom. Most of the time it will be near columns. This got me thinking... Is there any way that I can justify lapping at a critical section? is anyone familiar with this? is there any research or information? if I have #4 longitudinal bars at a critical section can I use a larger bar and be set? can this be quantified?

The firm does not want to tie their own rebar for the beams as it will take longer for construction....

 

[KootK]

In things that are not seismically critical, you can splice anywhere. Engineers often specify particular splicing locations as a matter of good practice but, in my opinion, that can be set aside where a legitimate need for high moment demand splicing exists.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[hssbrian]

KootK, it is not a critical seismic region, but it is seimic... I would still think splicing location matters...

 

[KootK]

This issue's actually been kicked around here several times in recent memory Brian. You can splice anywhere. Personally, I'd let this go. Especially so in a grade beam where you don't necessarily know which side of the beam the tension will be on at any location. You can get load reversal depending on if your load case is downwards gravity or upwards clay expansion / frost heave.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[hokie66]

If these are precast beams, are they considered to be simple spans, with some reinforcement then in a cast in place slab which then ties everything together? Some pictures or details would help.