Hello,
I want to do pushdown analysis of diagrid structural system but I find difficulty while analysis.The deformation of the building as well hinge formation is improper.I am bit confusing while taking point to consider to observe the displacement after removing diagrid and permisssible displacement of the buildings under gravity load?
Please find attached model and image
Dear Pragnesh,
As I understand, you want to carry out static pushover analysis for this diagrid structure, hence, you will load the model with lateral load gradually and observe the lateral deformation till failure.
1st, If you used linear model, the relation between lateral load and lateral deformation will be always linear with slope equals to the initial lateral stiffness of the building, which is useless. So, the used software should be able to carry out non-linear analysis ( I don't know which software you are using).
2nd, you should identify proper failure criteria depending on the expected failure mode, for example, in pure frame structure, the expected failure mode is plastic hinges at beam-col. connections, hence you have to define the failure criteria as moment-rotation curve or equivalent depending on your software.
in your case "diagrid structure", the structure will act as 3D space truss, it means that main straining actions are axial forces not bending moments, hence, the expected failure mode will be axial tension or compression within members not joints. So your failure criteria should be relation between axial load and axial deformations of members or equivalent depends on your software.
if you are using SAP2000, ETABS, or PERFORM 3D, you can use (Ten/Comp Limits) option to define max. tension and compression force in each member depending on its capacity, if the force in the member exceeded those limits the member will considered failed and canceled from stiffness matrix.
During loading, progressive failure in members will occur, and lateral stiffness of the building will be gradually decreased, the relation between lateral load and lateral deformation will be non-linear .
if you are using a software in which you can apply the load by a displacement-control rate , then it will be better. You can track the softening part of the behavior and you can calculate the load by summing up the reactions.
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