Heavy Distributed Load Steel Beam - Top Flange Bending Check?

[WiscEIT]

Hello everyone

I have read several posts here regarding local flange bending due to concentrated load due to wheel loads on bottom flange. But I have not come across any discussion on Steel I Beam supporting precast planks or load Bearing walls (Lets say 10k/ft)
My questions are

1) how do you check for whether a steel beam with precast planks sitting on top flange or a heavy load bearing wall sitting eccentrically on a steel beam works with local flange bending or not?
2) Section J-10 addresses all local issues in flange and web but it categorically says flange bending is only affected by tensile forces! Why is that the case? Will I check for local bending in flange if the precast planks were to bear on the bottom flange since that would then become tensile force acting on the bottom flange (My interpretation of tensile and compression force in the context of local flange bending is that force acting on any flange (top or bottom) that tends to compress the web would be compression force and the one that acts away from the web i.e. tries to pull the flange away from the web is tensile force

3) Last question! - What is the solution for local flange bending? Doubler plates and transverse stiffeners would increase shear strength but would either of the two help for flange bending? If yes, then how and through what load path

Thank you very much to the experts on this site!

 

[DrZoidberWoop]

The most common solution you will see to resolve local flange bending from concentrated loads is the use of transverse stiffeners. You can size and space them along a continuous beam based on how much tributary load length you assign to them (within reason).

AISC commentary, pg 16.1-450 (15th), indicates that the flange local bending check is only applicable for a single concentrated line load applied transverse to the beam web. No other conditions, even if it sounds like the description entails something that looks like it should be named "flange local bending."

 

[JoelTXCive]

Can you treat the extended flange leg as a cantilevered flat plate? Then do a calculation of the flange's capacity per linear foot? See below.........

 

[Hokie93]

If the load is continuous (along the length of the beam) and supported only by the flange, the approach suggested by JoelTXCive is reasonable. If the load is continuous across the flange width, the typical assumption is that the load goes directly into the web of the beam since that is much stiffer than the flanges. In that case, there is no flange bending to check. If the load is concentrated at discrete locations and supported only the flange, I have used a yield line solution in the past.

AISC 360 Section J10.1 is applicable only for tensile flange forces because the assumption is that tensile forces are resisted partially by the flanges and partially by the web. For compression, the force is assumed to be taken entirely by the web, with corresponding checks for web local yielding, web local crippling, and web sidesway buckling.

 

[WiscEIT]

Thank you guys for your response.

@ DrZoidberWoop Lets say I use one transverse stiffeners on each side of the web of a W beam (flange width 8 in) and I have precast planks on either side of the web sitting on the flanges (4" bearing for either side of planks) and my load per flange is 10kips/ft, what load would I size my transverse stiffener for because the web also takes a portion of the load. Also if you are saying its applicable to only single concentration load, then my loading condition does not require any local flange checks or web checks?

@ JoelTxCive Lets say my flange flies, how is the eccentric load from each side of the web being transferred to the web and the beam section as a whole

@Hookie93 Is there an eccentricity cut-off per your judgement beyond which we dont assume it goes directly into the web and hence would do local flange bending check? I understand yield line solution would give us adequate result for concentrated load. I fail to understand why would flanges only resist tensile forces. A compression force for example downward load on a top flange would still create stresses at the web-flange weld irrespective of directions. By the way, is my interpretation of compressive and tensile forces correct : downward force on top flange = compression, downward force on bottom flange = tension