Inverted t beam flange shear capacity

[Qris]

Suppose I have a reinforced inverted t beam (see attached file) used to support hollow-core slab.The flange width is so small (about 20mm - below minimum concrete cover as per ACI:318) that no reinforcement can be provided for it. How can you make sure that shear failure cannot occurs in the flange or it will not crumble when loaded over time ?
One solution could be to make sure that hf is high enough but I think it cannot avoid any crumbling.

 

[Agent666]

I'd start by complying with the minimum seating requirements for hollowcore, in ACI318 these are greater of 50mm or span/180. Then you can start to think of reinforcing it as the code writers probably intended. 20mm is far too small for seating, any tolerances on length of hollowcore unit and construction of the beam could quickly use up your 20mm.

Id consider the minimum ACI seating requirements apply after consideration of tolerances, so if you judge a cumulative tolerance of say 25mm, then minimum seating should be 50mm plus 25mm = 75mm minimum being detailed to ensure you meet the 50mm limit on site after consideration of tolerances.

 

[Agent666]

Check this document for one means of assessing the reinforcement in a corbel supporting flooring, plus there's a lot of other good stuff relating to hollowcore.

 

[Tomfh]

20mm is too narrow!