Dispersion Line for Padstone

[Scotty Boy]

Hi there,

I am currently designing a padstone to support a beam with a 77.63 kN end reaction. I am following the British Standard BS 5628-1-2005.

The BS code provides the following Figure for the design:



We see that the dispersion line illustrates the stress distribution at a 45 degree angle for a vertical distance of 0.4*h.

However, in my design, my wall is not deep enough to accommodate the full length of the 45 degree dispersion line, as shown below.





My wall is only 380 mm thick. To accommodate the full dispersion line it would need to be 1100 mm thick.

My question is, can I take the stress at the point that it marked on the diagram? Hence, (77.63 x 10^3)/(380 x 254) = 0.80 N/mm^2
Where 254 is width of the beam in mm.

Or would this be dangerous and I have to re-think the design?

 

[jhnblgr]

I would limit it to the inside face of the block, the distribution would still likely be 45 but as you say it’s are is limited due to the depth. But I don’t agree with the load distribution for the lintel since the block thickness isn’t great enough and the load isn’t centered. A high likelihood of cracking on the inside face.

 

[Scotty Boy]

Thanks for your feedback. I think I will use a column to support the beam then.