Simple Connection Design

[Szubert80]

Hi,

I`m wondering if there is any rule of thumb for beam to column simple connection design (let say using single angle clip) when there is no reactions specified on the drawing?
I have heard that I can take half of Vr of the beam and use it as reaction but I`m not very comfortable with that. Can you share some thoughts on that please?

Thanks

 

[structSU10]

usually you can take half the total load the beam can handle and design the connection for that - see table 3-6 from AISC. If the beams are composite, that number may be unconservative, and sometimes 1.2+ * max uniform load/2 is used.

 

[JedClampett]

I would provide the capacity of an AISC type II (now 10-1, standard bolt holes) connection with whatever your default bolt size (7/8, 3/4) is. If your reactions were any bigger than that, you'd know it.
Where I used to work, we did some big steel boiler rooms. We would only post reactions when they exceeded this.

 

[PMR06]

Are you the detailer or delegated connection engineer? If so, the EOR has not provided enough information to you, either a reaction or some kind of criteria to follow (50% UDL or other)

 

[Szubert80]

I`m EIT but sometimes I do also some detailing. This job is to prepare connection details and produce shop drawings. Taking 50% allowable UDL sounds good to me in that case where reactions are not provided. Thank you for your quick response.

 

[JAE]

Do you have a PE overseeing your work? Seems like what you are doing is "practicing engineering" without a license.

 

[Szubert80]

JAE,
I have PE who is going to check and stamp the drawings before it will be issued for construction.
Thanks for your concern.

 

[JAE]

OK - just asking.

 

[Lion06]

You need to get the reactions from the EOR. The beam tables in AISC can be unconservative if you have a heavy point load near one end.

 

[BAretired]

I would not seal the design of a connection in which the Engineer of Record had not given the reaction or described the criteria for design (such as 50% UDL).

BA

 

[mijowe]

You should get clear direction on the load from the EOR, but if it is a simple structure, calculating the load as a simple check should not be hard.

 

[dhengr]

Szubert80:
If you are in fact, already working with a PE on this detailing project; and he/she is going to be stamping and signing the drawings, why wouldn’t you go to him/her for guidance on this matter? It’s certainly not bad to get other opinions, but he/she is ultimately responsible for overseeing this work, and signing off on it.

 

[SteelPE]

What I have usually seen is to use 1/2 UDL for non composite beams and UDL for composite beams. It creates problems with the designs. I find that the EOR will use this method and we will end up with a girder to column connection that is 30' long with beams at 6'-0" o.c will end up needing to design the girder to column connection for 100k while the purlin beams need to be designed for 50k. (50k/beam x 3 beams/side x 2 sides)/2connections = 150k..... something is not quite right as we need to design the purlins to resist 150k while the girder needs to be designed for only 100k?

 

[steellion]

You need direction from the EOR.

 

[a2mfk]

Agree with all on asking your mentor/PE and also getting the reactions from the EOR. I think it is silly and a waste of money to over-design connections based on full beam capacity (shear or moment) instead of the actual reactions, and it is just because the EOR was lazy or forgot to put the reactions on the drawings. When I have done specialty engineering I have always requested the reactions "So that we can provide an accurate, safe and economic connection design." You will usually not get push-back if you word it in this manner.