Free End Wind Post

[Contraflexure74]

Hi,

I have been asked to install a wind post to restrain a free end of a masonry panel. I have a 215 inner leaf, a 180mm cavity and a 100mmm outer leaf, all blockwork.

The odd thing is the Arch wants to place the wind post on the inside of the inner leaf so I imagine the wind post will have to be bolt fixed to the inner face of the inner leaf and then tied to the structure over and at the floor level.

Has anyone done this detail before or have any issues with it. I 'm used to calling wind posts up built into the inner leaf or installed within the cavity.

John.

 

[Contraflexure74]

Sorry Guys,

Meant to add a sketch of the detail, see attached.

John.

 

[KootK]

It looks fine to me so long as the numbers work. My primary concern would be moment dominated punching shear in the slab.

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.

 

[Contraflexure74]

Thanks Kootk.

Would increasing the base plate size avoid this. The moment I have 26.5kNm. The slab is 200 in total (50 screed with A142 mesh) on a 150 prestressed hollowcore slab, and the voids have been filled locally in this area.

John.

 

[KootK]

Increasing the base plate thickness would help so long as the base plate were sufficiently stiff. That said, I don't know that you currently have a problem. Punching shear is just the failure mode that strikes me as being the most critical.

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.

 

[Contraflexure74]

Thanks Kootk.

I'm just not too sure how to convert the moment into a point load so I can get the precast supplier to check punching?

I know that Force = Moment/lever arm but is my lever arm the distance from the centre of the post to the edge of the baseplate?

John.

 

[KootK]

I don't think that you need to convert the moment into a point load. The precaster ought to be capable of performing the check with just the moment value and your base plate size.

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]

I wouldn't design the base connection as fixed. Just design the beam as simply spanning from floor to structure over.

The connection to the wall on the right side of your sketch is weak, if to scale. I would run a bent plate around the corner so you can bolt to the end of the block wall.

 

[BUGGAR]

I agree with KootK. Tell the precaster what you are doing - your loads will be similar to those from an offset lifting lug sometimes used to place precast panels in tight spots.

 

[Contraflexure74]

Thanks everyone. I should have said the wind post is now actually a cantilever up off the precast slab as the Arch will not permit a connection at high level as it will obstruct a glazed panel over......apologies. I spoke to the precaster and he seems to think he can only a apply a point load with his design software.

 

[hokie66]

That is a different problem entirely. I don't like your chances of cantilevering a 200 beam off of the end of a 150 hollow core slab. The slab would only have bottom reinforcement, and it is so close to the end, it won't take much moment.

Can you run the wind beam down to the next level to give you a backspan?