Base Plate: Shear value

Does Ram connection consider shear value for Base plate design ?

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  • Hello Nazmul,

    The AISC base plate design is based on the AISC Design Guide 1 Second Edition. According to the DG1 section 3.5, the shear in a base plate design can be handled in three ways:

    1. Friction between the base plate and the grouting or concrete surface
    2. Using a shear lug
    3. Shear in anchors

    By default RAM Connection checks the shear in anchors, that is why you see all the shear capacities being calculated according to the ACI 318 Appendix D.

    If you want consider the friction between the base plate and the concrete you need to check the “Include friction between base plate and support” option in Design criteria. This will enable the friction calculation which can be calculated just for the plate or Include it in the anchors shear capacity.

    If it is just for the plate a new capacity is added in the base plate section called “Friction shear capacity”. This depends on axial compression so for a base plate under tension the friction capacity will be zero.

    If you want the friction to be considered as a contribution of the anchor shear capacity then you need to check “Include anchor contribution to friction resistance”. This will include the friction contribution to the anchor shear resistance.

    Finally, shear can also be resisted by a shear lug. If this is the case you need to check the option "Include shear lug".This will enable all section capacities for the shear lug.

    Attached some screenshots to guide you in each option.

    PDF

  • Is there a way that RAM Connection will check the anchor bolts per AISC DG 1?  I am referring to the tension/bending/shear interaction due to bending in the anchors when oversized holes and welded washers are used.

  • Hello Andrew, RAM Connection base plate design is based on the AISC DG 1. As it is mentioned in the design guide, the interaction for tension and shear is done following the ACI 318 approach for both steel and concrete limit states. Could you please point out the section on the DG1 with your requirement.

  • 3.5.3 of DG1 talks about Shear in Anchor Rods (pages 28-29).  There is also example 4.11 starting on page 44.  I am referring to AISC DG1 (2nd Edition) for the page references.  3.5.4 refers to an interaction in the concrete rather than the steel.  Although ACI 318 still has an interaction equation which would consider anchor bolt steel strength, it just calculates the capacities differently and is less conservative than AISC DG1.

  • Hello Andrew, for anchoring to concrete RAM Connection is based on ACI 318 Appendix D and now Chapter 17 where the shear and tension interaction is done under ACI 17.8. Therefore, RAM Connection is not checking the shear and tension according to AISC 360-16 Sec J3.7. If this is something you usually do, we can log an enhancement and provide an option to perform this check for AISC base plates.