Shear capacity of dowelled connection across expansion joint
Shear capacity of dowelled connection across expansion joint
(OP)
Hi Folks
I have a suspended slab and need to transfer significant shear forces accross a mpovement joint. By UK codes the shear capacity of a deformed reinforcement bar = 0.6 x 0.9 x Area x fy. Now I can calculate the area of steel required to transfer the forces from one side of the suspended slab to the other side of the joint. But if the bars are loaded to near their shear capacity I would think that the bar will spall off the edge of the concrete (250mm slab).
How does one calculate the capacity of the dowelled connection? I would think edge distance would play a major role (distance from dowel bar to slab edge) and that the capacity of the shear connection will be governed by the concrete's capacity to absorb the shear stresses from the dowel bar and not by the shear capacity of the dowels.
I have scanned the forum and cannot find anything on this.
Thanks
I have a suspended slab and need to transfer significant shear forces accross a mpovement joint. By UK codes the shear capacity of a deformed reinforcement bar = 0.6 x 0.9 x Area x fy. Now I can calculate the area of steel required to transfer the forces from one side of the suspended slab to the other side of the joint. But if the bars are loaded to near their shear capacity I would think that the bar will spall off the edge of the concrete (250mm slab).
How does one calculate the capacity of the dowelled connection? I would think edge distance would play a major role (distance from dowel bar to slab edge) and that the capacity of the shear connection will be governed by the concrete's capacity to absorb the shear stresses from the dowel bar and not by the shear capacity of the dowels.
I have scanned the forum and cannot find anything on this.
Thanks






RE: Shear capacity of dowelled connection across expansion joint
I'm assuming something has changed if you need to transfer shear across an expansion joint. If that's the case, you need to modify the design.
RE: Shear capacity of dowelled connection across expansion joint
RE: Shear capacity of dowelled connection across expansion joint
htt
RE: Shear capacity of dowelled connection across expansion joint
One problem, especially in residential buildings, is the noise these connectors make when they move. Sounds like a rifle shot when the built up friction releases.
RE: Shear capacity of dowelled connection across expansion joint
RE: Shear capacity of dowelled connection across expansion joint
So you use some device with an open joint and add if required geometrical restraining components to it.
At least a shear friction mechanism is not directly of use, since the formation of the compressive strut from ample contact is lacking.
You can get compressive strut but for the limited area of the projection of the rebar, or as hokie66 implies, the limited area of the proprietary connection, hence seen ashe says "minor forces".
For big forces you need to devise a detail for the proper wanted transfer.
However not as "minor" forces in proprietary devices, can go tens of tons, more than enough for lots of common building tasks, surely not for bridge works, concentrated forces.
RE: Shear capacity of dowelled connection across expansion joint
I'm not sure if the OP question was answered however - Is there a calculation that can be done to determine concrete failure of dowel joints that incorporates edge distance? I don't think so... Ramset, Hilti etc give capacities for bolts with defined edge distances, but I think alot of this is based on testing..
RE: Shear capacity of dowelled connection across expansion joint
Kieran
RE: Shear capacity of dowelled connection across expansion joint
I think I will go for a proprietry product like Ancon, the detail would have been a simple dowel rebar to the middle of the slab depth with sleeve to one side allowing sliding.
I know HILTI have software that calculate the capacity of the dowel but also not sure on what they have based their calc