Beam Lap Splice

[smarky0]

Hi!

This is my first time posting a thread here but I've been reading a lot of threads and responses which are really useful.

There's just a personal question bugging me right now..

According to what I read from the code, no splices shall be allowed at 2 times the deapth of beams designed against seismic forces. So I see to it that all splices must be within the middle part of the beam (of course not at the Mmax location). But then I read some articles saying a percentage of the rebars should be spliced within the support to prevent progressive destruction during column failure.

Hope you could clarify a few things for me. Your advice will be greatly appreciated.

 

[KootK]

Welcome Smarky0.

1) For the sake of progressive collapse, the important thing is that rebar is continuous over the supports. The location of the splices is not that important. If anything, the system would likely perform better with the splices located at mid-span as the demand on the integrity steel is highest at the supports.

2) For beams that are not part of the lateral system, it makes sense to splice the bottom steel at the supports where demand (parabola) is lowest under gravity loading.

3) For beams that are part of the lateral system, the peak demand (linearly varying like shear diagram) for bottom reinforcing is often at the supports, just like the peak integrity steel demand. In such situations, it makes perfect sense to do all of your splicing at mid-span.

That was a mouthful; hopefully it helps some.

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