Simple Shear Connection Vertical Eccentricity 1

[jseng9]

Hi,

I'm learning simple shear connection design and I'm having trouble finding the plate vertical eccentricity. I'm following a lesson from Risa where they calculate the distance ey as 0.51. I'm not sure where this comes from and wanted to see if someone could help me find the plate vertical eccentricity in this example. Please find the photo of the connection attached. The plate is 0.375*3*12 (inches). I get how ex = 0.5+1.5 but do not know how to calc ey. Thanks for your help!
Image of connection is here:

https://imgur.com/gallery/CFKRsmX

 

[r13]

Ey is the difference between the center of the bolts and the geometry centroid of the wide flange beam. In your case, the center of the bolts measured from the top flange y = 2.44+1.5+3+3/2 = 8.44", for W18 with d=17.9", ey = 17.9/2-8.44 = 0.51", check!

 

[jseng9]

wow! You are a life saver! I couldn't figure this out and you have been so helpful. Really appreciate it!

 

[r13]

Glad to be helpful. But its not a home work problem, right? No matter what, always know what you need, then start with a good reference point to make things clear and easier.

 

[jseng9]

Hi there, would you be able to help me calculate the plastic section modulus of the net plate as well? For the section modulus of the plate I simply used: tp*plate_depth^2/4. I'm thinking I would do the same thing for the net section but subtract out the area of the holes. Risa is getting 9.56. And no this is not homework. I'm an EIT and wanted to create a spreadsheet for simple connections, mostly for spot checking steel shop drawings. Thanks!

 

[r13]

jseng9,

Please have a look on the linked blog. Let me know, if you still have question after reading. Link

Note: Draw a section cut through the bolt line, that's the section to be used in the calculation. Also, don't forget to use correct hole size.

 

[jseng9]

Hi This post is very helpful. Yet, I understand the concept of section modulus in general and was able to get the same answer as risa for section modulus which is (0.375^12^2)/4 = 13.5. However, I'm having trouble when it comes to the net section modulus

 

[r13]

Draw the cross section through the holes, so for 4 bolts, you shall have 5 separated plate segments. Then use the same concept to get the result (ΣA[sub]segment[/sub]*distance to the NA).

 

[jseng9]

Yesss! I got it. Thank you so much

 

[r13]

I think this is a very good exercise in learning the underlay concept, though it (plastic hinge at net section of connection plate) is not a typical/practical engineering problem, but a practice for your own good.