Concrete Beam Repair

[tclat]

Hi,

I'm reviewing a concrete beam in a building under construction which was loaded accidentally from a falling object. Some diagonal shear cracks have formed near the supports on both faces. There are no flexural cracks so I'm thinking that the bars have not yielded and are probably still ok. Since we are still in the construction stage of the project, I recommended demolishing the beam and reconstructing. The project manager wants me to review other options including epoxy injection since the the location of this beam and the time it would take would hold back other works. I'm a bit weary about this this option. Are there other suitable options or should I press the issue of demolition.

Thanks

 

[JedClampett]

If the beam is not visible, you could add steel plates to the high shear region and use them to replace the stirrups. The carbon fiber guys will tell you they can solve any overstress and maybe they can. Or maybe pour another beam next to the existing one.
I'm not sure I'd be too quick to demolish. If you could get the concrete out of there and leave the original bars, that would be great, but that's kind of tricky.

 

[KootK]

You might not even need to reinforce for shear. Beams with stirrups are supposed to develop diagonal shear cracks at ULS. The stirrups don't do much until cracking develops after all. If aesthetics are not a concern, I'd evaluate the size of the cracks and what that might imply for corrosion resistance and Vc shear capacity. Got any pics or measurements?

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.

 

[WARose]

In addition to what the others have said.....I'd try to get some idea of how much force it saw from this impact. If you can establish a maximum.....that might give you some peace of mind.