- #1
CalebP
- 9
- 0
I'm having quite a bit of difficulty with the question posted - even from part 1.
I understand I have 6 unknowns and 2 seperable beams so we're statically determinate here. I can split the pictured beam into two parts at the hinge and apply the static equations twice.
On the right part I find that all forces are equal and opposite (Rbx = Rcx, Rby = Rcy, if drawn in the correct directions), however I notice I never used the moment equation or the fact that the reactions at B occur 3m higher than C - I think this is my first pitfall. Also, taking moments about any point on the RHS FBD results in all reactions = 0. For example, ƩM(c) = 0 ⇔ Rby*3 = 0 Rby = 0.
I'm around 99% sure my methods are wrong above. I run into similar problems on the LHS of C. I've tried splitting that one further into parts AD and DB, and replacing the bend by axial reactions Nad in both. I get a little further here, but again don't even use the 6m height of the bar, so I'm wrong somewhere.
I can't do part 2 without the reactions first. I'm sure I'd run into difficulty though due to those turns... how am I supposed to orientate SF and BM diagrams like this. On beams they purely run in the x-direction to the right, do I draw SF/BM diagrams along the y-axis for these beams?
I can probably get the displacement of D due to δ = NL/EA.
The last part is simply (I think) discovering the centroid of that cross-section - which I can do.
I think my greatest misunderstanding here is applying the sum of moments equation multidirectionally.
Thanks guys.
I understand I have 6 unknowns and 2 seperable beams so we're statically determinate here. I can split the pictured beam into two parts at the hinge and apply the static equations twice.
On the right part I find that all forces are equal and opposite (Rbx = Rcx, Rby = Rcy, if drawn in the correct directions), however I notice I never used the moment equation or the fact that the reactions at B occur 3m higher than C - I think this is my first pitfall. Also, taking moments about any point on the RHS FBD results in all reactions = 0. For example, ƩM(c) = 0 ⇔ Rby*3 = 0 Rby = 0.
I'm around 99% sure my methods are wrong above. I run into similar problems on the LHS of C. I've tried splitting that one further into parts AD and DB, and replacing the bend by axial reactions Nad in both. I get a little further here, but again don't even use the 6m height of the bar, so I'm wrong somewhere.
I can't do part 2 without the reactions first. I'm sure I'd run into difficulty though due to those turns... how am I supposed to orientate SF and BM diagrams like this. On beams they purely run in the x-direction to the right, do I draw SF/BM diagrams along the y-axis for these beams?
I can probably get the displacement of D due to δ = NL/EA.
The last part is simply (I think) discovering the centroid of that cross-section - which I can do.
I think my greatest misunderstanding here is applying the sum of moments equation multidirectionally.
Thanks guys.