RC Beam module, support reinforcement

[Anonymous]

Hi!

Last time, I was wondering where's in the RC standard point that says, that when we have masonry support for RC beam (eg. lintel) we should add additional transversal reinforcement over it?

See the attached image, please.

Do you give in projects those transversal reinforcement (in green box) when you have beam support on masonry?

 Thanks in advance.

[Refaat]

Hi

I think existence of stirrups within the support width (Masonry wall) due to the fact that the effective lintel span considers from the center of support (Shot 1).  Therefore RSA calculates the internal forces (Moment, shear…etc) and generates the reinforcement (longitudinal & transversal) based on this fact (Shot 2).

Refaat

[Anonymous]

Hi,

Refeat, thank you for reply. I know that in the masonry support Robot takes the forces from point of effective lenght of support, but where it comes from (literature, standards)?

The effective span is also larger for concrete support, isn't it? But then you take the effective forces from surface of support.

I've checked mine literature for the concrete structures, and I've never saw the beam, that has stirrups in the drawing far more than the edge of opening. Nowhere also any words about masonry supports and different stirrups distributtion upon it.   

The standards also don't clearly say (did I miss something?) that when you have masonry support, then you should take forces from point where you start effective span instead surface of support. I've checked many projects - every beams has always stirrups starting from surface of support - no matter is it a masonry or concrete support.

Isn't have matter what kind of masonry support is? Ceramic bricks, silicates, aerated?

Strange to me...

[Anonymous]

Hi,

Any ideas ?

What about starting point for distrubution stirrups when it's masonry support?

Could anyone give me some examples from literature or standards, that explain why, when it's masonry support, it should be check the cracking section that starts from effective lenght point (red line in attached image) rather than from surface of support? 

Thanks in advance !

[Artur.Kosakowski]

IMHO the position of the 1st stirrup for concrete support is due to the fact that you assume the direct load transfer from beam to support and the bond between the beam and the support can resist rotation without damaging the support itself. For masonry this is not so certain and you may actually even prevent this connection due to the fact that the 'uplift' of the end of the beam (as it bends under the load) will crack the masonry support (wall) in this location. If so you should extend the stirrups beyond the edge of the support. 

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