Hollow core slab - beam details

[insajn]

Hello,

I'm designing a parking lot with prestressed hollow core slab and dropped beams.
But before I want to choose the preliminary dimensions of the beams I want to know how will the slab connects to the beam ? Like it's rebars detailing. Plus should I make the beam width larger than the column's ? So that the column in the second floor won't rest on slab directly.

I drawed a picture in the attachments

 

[ash060]

Typically there are rebar dowels that are placed in the voids in the hollowcore planks. The dowels are CIP with the beam, they can be post-installed as well. You can go to various manufacturer's websites and they have design guides that show typical details for all kinds of conditions.

Oldcastle, spancrete are just a couple that make plank. A Google search should yield good results.

 

[Prestressed Guy]

You do not say if these hollow core planks get a topping or not. I will assume topping since you said "floor". Generally you want the beam to be an inverted "T" beam which will have a bearing notch that is the depth of the hollow core plank. This is important from a safety stand point because before grouting the hollow core slides very easily on the concrete beam and needs to be restrained so that it does not shift off the bearing. I specify a 3" bearing width and use a 4" wide notch. This means that if the plank shifts as far as possible it will still have 2" bearing on the other end.

The final connection is provided by grouting the end of the plank to beam joint and by rebar that crosses the joint and ties into the horizontal shear reinforcement that projects for the top of the beam. No actual connection is made to the plank other than by means of grout because it is not possible to cast the plank with any embeds in them due to the extrusion or slip form process.

 

[dik]

Just a caution... if in a cold area, make sure that water does not get into the cores... can freeze. Used 12" deep for a couple of parkades, and, have worked well... one over 25 years old and still in service. Just have to be careful with detailing.

Dik

 

[insajn]

Thanks everyone

 

[Prestressed Guy]

On hollow core projects I put the following note in the general notes.
CAUTION:
If voids are grouted solid at ends and a waterproof membrane is not on top of the exposed hollow core, the cores may fill with water. This could lead to damage. Contractor is responsible to protect exposed hollow core until a membrane is installed.