Hi All,
This is for an assignment and I am fairly new to SPACE GASS and structures in general so bear with me.
The model is giving me all sorts of instabilities for translation and rotation. There are 6x18m bays resting on piles roughly 30m long. One end connects to a wharf and the other rests against an abutment. The model has no general restraint.
1. What type of node fixity (if any) should I put at the ends of the trestle to model connection to the other structures (note that I have tried fixing these nodes to make the structure more stable but it doesn't help)?
2. What type of general restraint should I have (if any) and how does this affect the results?
3. What in your opinions could be causing the instability? Have I released the end fixity of too many members? Or is the structure in general just really unstable looking?
4. Does the sizing of the members affect instabilities in any way? If I beef up the members could that possibly help?
5. If I start messing around with end fixities what members should I fix first? The top chords are fixed but basically every thing else is pinned. Is it usual practice to fix the "lateral chords" (members running parallel with with the Z axis) and/or the upright members?
6. Is making the truss more like a frame a bad idea? Why?
Thanks everyone.
This is for an assignment and I am fairly new to SPACE GASS and structures in general so bear with me.
The model is giving me all sorts of instabilities for translation and rotation. There are 6x18m bays resting on piles roughly 30m long. One end connects to a wharf and the other rests against an abutment. The model has no general restraint.
1. What type of node fixity (if any) should I put at the ends of the trestle to model connection to the other structures (note that I have tried fixing these nodes to make the structure more stable but it doesn't help)?
2. What type of general restraint should I have (if any) and how does this affect the results?
3. What in your opinions could be causing the instability? Have I released the end fixity of too many members? Or is the structure in general just really unstable looking?
4. Does the sizing of the members affect instabilities in any way? If I beef up the members could that possibly help?
5. If I start messing around with end fixities what members should I fix first? The top chords are fixed but basically every thing else is pinned. Is it usual practice to fix the "lateral chords" (members running parallel with with the Z axis) and/or the upright members?
6. Is making the truss more like a frame a bad idea? Why?
Thanks everyone.
