Shear capacity of an end plate connection

[novembertango88]

Hi,

Can anyone offer a reason why you can use the ultimate strength of steel (fu,p) when checking the net section of an end plate for shear?
Rather than the tensile strength of steel (fy,p) for the gross section...

The extract attached is from SCI Simple Joints to Eurocode 3.

Thanks, Steve

 

[dik]

It is the lowest of either the gross section based on fy or the net section based on Fu, adjusted for block shear. The value for the net area will be a 'brittle' type failure due to the discontinuities and will occur due to Fu and the value for the gross area will be based on the yield of the entire cross-section, based on fy.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[novembertango88]

Thanks dik. That makes sense, very confusing that the net capacity often comes out greater than the gross capacity though!

 

[jayrod12]

I don't find that odd at all. For gross section capacity, you're just making sure you have enough steel total, i.e. general member size essentially. For the net section, you're taking into account all of the lost material and new potential failure lines caused by the connection details. There's often much less area of steel on the failure planes once you look at the net section.

 

[dik]

happy to help...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[dauwerda]

Can anyone offer a reason why you can use the ultimate strength of steel (fu,p) when checking the net section of an end plate for shear?
Rather than the tensile strength of steel (fy,p) for the gross section...

Perhaps different countries use different nomenclatures, but I am used to "tensile strength" referring to the ultimate capacity of the steel, f[sub]u[/sub] where as yield strength refers to the yield strength of the steel, f[sub]y[/sub]

The gross area checks use the yield strength because if the steel were allowed to go past yield over the gross area it would result in large strains and large permanent deformations.

The net area checks use the ultimate strength because the holes that are deducted make up a relatively short area of the member and it is ok/not detrimental to the performance of the connection/structure for the steel to go past yield in these areas. Even though this results in more strain and possible permanent deformation (which is avoided for the gross checks), it is over a very short length and is negligible to the performance of the structure.

 

[dik]

Dauwerda I used Fu and fy out of habit. My SMath programs used F[sub]u1[/sub], etc and f[sub]y1[/sub] as variables, for ultimate tensile and yield values for steel type 1. Your f[sub]u[/sub] and f[sub]y[/sub] are common in Canada.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik