Best detail for pinning steel rafter to concrete panel?

[Tomfh]

What is your preferred detail for pinning a steel rafter to a concrete panel?

Here are some details I grabbed from the web, to aid discussion.

Some considerations:

A. Cast in weld plates vs. anchors?
B. Flexibility requirements? How to assess the anchor tension?
C. Seat vs web support?
D. Detail at joints vs Detail clear of joints?
E. Consideration of rafter size on connection choice?

 

[Tomfh]

I mean how do you assess the stiffness of the connection and the resultant flexural demand that the beam imposes on the connection. These are nominally pinned connections but in reality will have some degree of rigidity which will cause additional tension in the anchors.

Do you have a link to those RJB details?

 

[rowingengineer]

I assess the connection using the finite element with the component method to get the spring stiffness, referred to as K which can be used by most Australian softwares.

The RJB is a manual I have picked up along the way, send me an email, it is my user name + @live.com.au

 

[Brad805]

I would be curious to hear more about the FEA or see the manual from AU. The steel connections in our area are typically delegated, and we do not usually have the info needed for a proper FEA. The most common details we are stuck with are simple tabs or angle clips. I have read about others FEA analysis, but we usually use the simple PCI or CPCI suggestions and use additional HCA.

 

[Tomfh]

Rowingengineer. Thanks, I’ll send an email.

As for the component method, how do you model the bolts and slotted hole using that method? How do you convert the slip behaviour into a k value?

 

[civeng80]

rowingengineer

In doing a FEA to determine the moment transfer from beam to panel, do you find that you get a significant moment transfer compared to the moment transfer due to eccentricity ?

I have never done a FEAon tilt up panels and work out the moments due to eccentricity and panel out of straightness. I then use the Green Book method to check panel strength and serviceability. I have always wondered about that extra moment due to rafter to panel moment transfer.

 

[bones206]

With extended shear tab connections the shear tab is designed to yield before the weld ruptures. So the greatest moment the embed plate can see is the moment at first yield of the shear tab = Fy*S. Would this be a reasonable upper bound design moment for the embed plate, or way too conservative?

I traditionally have only designed the embed plate with the moment due to eccentricity of the bolts...