Can pinned support / pin joint transfer moments in 3D?

Question

What's an authoritative definition of whether the idealized pinned support and pin joint can transfer moments in 3D?

Most sources say both of them cannot transfer moments but are apparently only considering 2D. A real pin joint obviously can transfer moments about all axes normal to the pin's axis. So is an implementation of the ideal pin joint really more like a ball joint than a pin joint?

I assume a pinned support is the same as a pin joint but with one end fixed to ground. But maybe they have different numbers of degrees of rotational freedom?

For example, if this support can carry moments about two perpendicular axes (red arrows), would it be correctly called a pinned support?

In comparison, this one has all 3 rotational degrees of freedom, so is it still a pinned support?

Answer 1

Yes it can, and in many designs it should be a pin support along one axis and fixed support along other. In many trusses and bridges that is the case.

The design software when defining a joint have the joint degrees of freedom choices. Among those are the option to define the joint a hinge along one axis but fixed along the others.

You can even have joints or supports that can have, rigid, pin, or spring or even predefined varying stiffness and ductility restriction on rotation, settlement, lateral displacement, moment transfer. This is becoming more advantageous in seismic design. Where one expects different behavior of a structure under different spectra of earthquake.

Between the two extremes of a pin joint and fixed join one can define the semi fixed joint or fixed but after a certain stress behaving like a hinge.

In real construction of a joint there is always joints that are legally considered pin or fixed but they behave a certain mix of both, but you design them depending on what the code defines that type ofjoint.