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Hi Professor Sean!! I have a conceptual question, why do you call it in some moments āThe Global reference frameā if we are building a plane along de local axis of the member ?
Brazilian guy attending to your classes!! The best experience of courses that i ever had !
The term global reference frame simply refers to the fixed cartesian reference frame the whole structures exists within - the āworldā reference frame, essentially. In contrast, the local reference frame refers to a cartesian reference frame that is aligned with the individual structural member.
With the two reference frames defined, we can use a simple matrix transformation to describe the orientation of any member (i.e. its local reference frame) within the fixed global reference frame. Understanding how we build local reference frame for a member and how this relates to the global reference frame - in other words, how we encode member location and orientation, is critical when it comes to building models of 3D structures.
Side note - in some cases, a memberās local reference frame will be aligned perfectly with global reference frame, but generally for 3D structures, this will not be the case.
I hope that helps - let me know if any confusion persists.
SeƔn
I appreciate that @Pedro_Henrique_Soare - youāre very welcome aboard!
SeƔn