Hello,
I am designing a post-installed base plate and looking at the anchor plate design based off of AISC Design Guide and CBFEM. When I run the analysis based off of AISC Design Guide, my concrete breakout utilization is at 71%, however when I run it with CBFEM, my concrete breakout utilization is 160%. Looking at the detailed report, the Psi parallel value is 2 with AISC and 1 with CBFEM. Could you provide some clarification as to why this is different between the two methods and any insight as to which method I should design to. The loads and geometry of the baseplate are identical between the two methods. I have attached the detailed reports for both methods. Thank you.
Hi Nicole,
In the past, designers have found two articles helpful when considering different design methodologies within PROFIS Engineering. The first article is USING CBFEM TO VALIDATE RIGID AND NON-RIGID BASE PLATE ASSUMPTIONS, which briefly explains the reasoning behind the methodology for anchoring connection design. The second article, Profis Engineering Base Plate Module, offers more details on the AISC design guide methodology.
Regarding Ψparallel,V, section 17.7.2 within the ACI 318-19 Chapter 17 anchoring-to-concrete provisions requires analyzing edges perpendicular to the direction of the shear force (17.7.2.1a or 17.7.2.1b) as well as edges parallel to the direction of the shear force (17.7.2.1c). Section 17.7.2.1c states that edges parallel to the direction of the shear force are permitted to be twice the value determined from either equation 17.7.2.1a or 17.7.2.1b as well as taking the modification factor for edge effect, Ψed,V, equal to 1.0. The PROFIS Engineering software represents the provisions of Section 17.7.2.1c through the modification factor Ψparallel,V. For edges perpendicular to the direction of the shear force, Ψparallel,V = 1.0. For edges parallel to the direction of the shear force, Ψparallel,V = 2.0.
If you have any further questions or concerns, feel free to reach out to hnatechnicalservices@hilti.com.
Regards,
Ashley