Dear All,
I am modelling reinforced concrete structure by using concrete damaged plasticity model. I apply seismic loads. But when I increase the applied load, the displacements and stresses are always increasing. In other words, the structure never collapse. I am wondering that do you have any idea how to be determined the failure load and how can we distinguish the time of failure.
Thanks in advance.
Dear Mehmet,
Initially, we must distinguish between collapse and damage. Collapse is global instability whereas damage is a local phenomenon. If you get high damage locally, it doesn't mean the structure will collapse. High damage can represent a local crack while the structure can still take up a load. If you want to see the structure collapse, you must do a buckling analysis of the structure. When the structure collapse (buckles), at least one eigenvalue of the global stiffness matrix, becomes zero or negative.
To check buckling/collapse, do not look at damage but look at displacements of nodes. You must see few nodes getting very large displacements suddenly. Also look at the global force (reaction force). The force must drop at approximately the same time when you see nodes having large displacements. This is an indication of global instability in the structure (collapse).
Best Regards
Waleed E. El-Demerdash
Dear Mehmet,
Initially, we must distinguish between collapse and damage. Collapse is global instability whereas damage is a local phenomenon. If you get high damage locally, it doesn't mean the structure will collapse. High damage can represent a local crack while the structure can still take up a load. If you want to see the structure collapse, you must do a buckling analysis of the structure. When the structure collapse (buckles), at least one eigenvalue of the global stiffness matrix, becomes zero or negative.
To check buckling/collapse, do not look at damage but look at displacements of nodes. You must see few nodes getting very large displacements suddenly. Also look at the global force (reaction force). The force must drop at approximately the same time when you see nodes having large displacements. This is an indication of global instability in the structure (collapse).
Best Regards
Waleed E. El-Demerdash
Dear Mehmet did u solve ur problem . If yes kindly advise . I am facing same issue
thanks
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