Seated beam connection 1

[civeng]

Hi everyone,
I'm designing a seated connection for a tubular beam connecting to a tubular column. I find that the ways i've seen to establish the required bearing length (N) are a little unclear. Since N is an important property for determining the thickness of the angle which will be used as the seat and the excentricity of the load, I was wondering if anyone has a good rule of thumb or precise way of calculating N.
Thanks in advance
Steven
Quebec, Canada

 

[ishvaaag]

1. You may fix the point of reaction by welding a plate...at least at one end.

2. A procedure to determine eccentricity of the reaction but for double tee loading is given in Ensidesa Manual Tomo II** p. 7.7 3-1. The thing is that nor web thickness nor to end of fillet (required) dimensions are available for pipe built trusses, for tubes some adaptation maybe made to some risk. The manual also gives tables for spanish shapes etc.

3. Also for double Tee loading I have a Mcad worksheet made and think posted at the Collaboratory, if you can't download, I can send it.

4. Work in the descent must be minimum, so the reaction at end will move inwards till the deformation work is minimum and still satisfies equilibrium. Since the reaction is constant, and the deflection will be lesser the more closer it is to the top welded end of tha angle, any support length that satisfy the capacity of passing in bearing to the truss itself should be a good guess of your supported length, hence eccentricity known. So your problem resumes in guessing what length of lower chord you need supported to properly take the reaction. This can be even ascertained by FEM, or simply assumed.

5. The Design Guide for Hollow Structural Section Connections by Packer and Henderson of your CISC have at least indications for end connection for HSS ... that may be late to implement. In any case worth to have and look at.

 

[civeng]

hI ishvaaag,
For your 2nd point, I stayed conservative and used the thickness as the web and the end of fillet.
What I did, also, was determine the bearing length using the load which was the maximum the tube was going to have to hold:
max load = 1.1*0.9*web thickness*(N+2k)*Fy
solving for N.
I would like to know the web address for your mcad worksheet if possible.
Thanks for responding ishvaaag
Have a good one.

 

[ishvaaag]

SO if you have a good guess of the required supported length problem solved as per point 4 above.

Site is

http://collab.mathsoft.com/~Mathcad2000/

And there are lots of my worksheets within the civil engineering folder. It may take a bit to find any specific you look for between the hundreds there, so keep the site but still I can send to you it via e-mail.