beam splice model

huangyhg

beam splice model
please see attach sketch. one splice in one span works fine. but when i placed two splices, left most span, both sap and staad show instability. but it is a real life situation and a evry senior engineer is doing it manually. i just wanted to cross check and learn using s/w. any tips ?
the first pin on the far left (just to the right of the far left support) should not be there.  you can't have a pin like that and remain stable.
also, it appears on the far right spans that you have double pins (two small circles side by side).  a joint must have at least one non-pinned   
jae is correct.  i hope it is not "a real life situation".
quote:
but it is a real life situation and a evry senior engineer is doing it manually. i just wanted to cross check and learn using s/w. any tips ?
what is s/w?  if senior engineers are doing this, they ought not to be senior engineers.
ba
i believe that s/w is software.  at least that is what a few other engineers at my office call it.
joel berg
i assumed as much.  is it too much trouble to write the word software, particularly when you are expecting   
it's not stable.  the span on the left is the issue.  it has a mechanism in it.  if the support farthest to the left was fixed instead of pinned then it would be stable, but as it stands, it isn't stable.  it shouldn't take software to see that.
if you draw a fbd of each individual member you will see that the two left-most   
spans 2 and 4 are also problematic, not just span 1.
the thing is...with a four span cantilever and drop-in system, you can only have three hinges and remain stable.  the sketch shows six, although in two cases they are sort of double hinges, which makes no sense.  perhaps the op can advise what he really means.
i agree with hokie here.  this setup makes no sense in the real world.  it is inherently unstable three times over.
mike mccann
mmc engineering
dgkhan,
i agree with what the previous posts have said.
only one of those thre spans is truly stable.