Length of stiff bearing from BS EN 1993-1-5

[SallyBee]

Hello

BS EN 1993-1-5 says that the length of stiff bearing should not be taken as larger than hw, can anyone tell me why that is?

Thanks

 

[Agent666]

I don't know for sure, but the only logical explanation I can think of is that it is something to do with the vertical stiffness of the web and its ability to distribute the loads to the full bearing surface. The stiffness of the bearing surface is possibly therefore partially influenced by the depth of the web?

Deeper supporting webs can naturally distribute the loads to a wider width than shallower supporting webs.

 

[SallyBee]

Thank you Agent666, that makes sense.

It's frustrating that it's not explained in the standard nor can I find any reference to it on the web. My problem is I have a stiff bearing length much larger than the depth of web and If I ignore that one statement I can get the results I need.

 

[hokie66]

I don't know the BS either, but that clause would be to limit web crippling. And I think hw would be the height of the web between the flange fillets.

 

[klaus.]

It's frustrating that it's not explained in the standard

a code is not a student text book ....
Explanation for formulas or procedure might be found in Code commentary books
Since BS is same as Eurocode you might find information searchng Eurocode

 

[Agent666]

Sallybee, take a look at section 6.2 of this commentary document. This explains their thinking at least and refers in passing to the web depth being a factor in the length over which the bending in the flange is resolved.

They are assuming the patch load is resisted by the flange bending only and ignores the web as its assumed to be stressed to yield in the transverse direction. This wasn't really clear in the standard so hopefully it helps establish what is being checked here.

 

[Shu Jiang PEng SE]

Stiff bearing length effects the stability factor KF, large stiff bearing length means large KF. The limitation on stiff bearing length, I think, is to avoid over estimate of restraints of the wall to the web.

J&J Structural Consulting Inc.
Structural design, analysis, inspection, review and stamping, and connection design

 

[SallyBee]

Thanks All.

Agent666, that document is very useful- thank you!