How exactly does a wishbone work? I have observed it being used 1) at jacket to pile connections to restrict vertical loads and allow lateral loads at coincident joints and 2) for connecting a beam placed directly on top of another ( Bottom of steel on Top of steel).
In the second case, is it appropriately used? will a rigid link made by offsetting one beam above another provide accurate results? Is there any other way to properly model a secondary beam resting directly on top of a primary beam like a UDL in such a way that loads are transferred from top to bottom while both act monolithically?
Hi Oluseun Olashore,
It depends on the connection between the primary and secondary beam resting on primary. Usually they will be welded all along the length. in that scenario, once can model as single element with equivalent section properties computed for both primary and secondary beams and design for the combined sections. Incase the secondary is not fully welded(may be bolted) one can use the wishbone to transfer the force from secondary to primary, similar to the Leg/pile connection (where only lateral load is being transferred using wishbone)
Introducing infinitely rigid links should always be exercised with caution. ideally, the link should be of realistic rigidity. If no significant secondary moments, then OFFSETS are can be used. For the beams, longitudinally bolted one above the other, wishbone gives grossly erroneous results. In fact , longitudinally bolted beams will bend independently with different radii of curvature.