I have found capacity curve for plane frame using SAP2000.I want to find the capacity curve of 3D frame using the results of plane frame. How can I get this?
Unfortunately I think you need a 3D push-over analysis in order to take into account torsional effects due to modifications in stiffness and strength and ductility along the building (plane and elevation). It is quite important to select the right control point before running the analyses.
If your building is 100% symmetric (for the at hand direction in which you apply your seismic load) thus has a normalized stiffness distribution then you can do it.If not then you will need to perform a 3D POA analysis as suggested by Roberto.
How can I do pushover analysis of setback building in SAP2000?How can I apply load in irregular structure?
Distribute your load according to your mass distribution. IBC forsees a triangular or parabolic distribution which will be applied at each floor. This is not realistic though if your building is irregular. Eurocode uses a more general formula to calculate the force for each floor Fi =V (mi zi / Sum (mj zi)).where V is the total base shear, mi being the floor mass and zi the floor's height from ground level. After you calculate the force that will be applied at each floor you will have to distribute the load according to your slab's mass distribution.An easy approach is to calculate the floor's mass that will be carried by each column or shear wall.Then distribute your load at each joint Fjoint = Fi mjoint / mi.
I hope this will help you to solve this issue.
Thank u all.Thank you George Markou Sir for all your guidance. Can you plz check the model attached here. I have calculated the load for each storey level and then applied at the specified application point. Suppose floor plan of ground storey is 16m*16m, then load is appled at 8m*8m.In top floor the plan is 12m *16m, then for that storey,I applied at 6m *8m.
You are welcome my dear. Do not forget to apply plastic hinges at your columns and beams. The quake loads in your model are applied through the diaphragm which is approximate. As for the values you have to check by your self if they are correct or not.
Yes I have provided hinges.The vaues are correct I think. I was confused about the point of application of load for irregular structure.
Your plan views' geometry is not irregular so it should work with an acceptable accuracy (given that the loads are applied along the x or y).
For a symmetric building for eg plan is 20m *20m and beam and column dimensions are same throughout the building, the capacity curves obtained from pushover X and pushover Y are different.Can anyone tell me why is it so?
Check how many openings you have in each direction. If they are the same in number then check for differences in the spans' lengths.Your model should give you different capacities according to its geometry.
The span length, no. of bays,openings everything are identical in both directions.load application is also at centre of mass for both direction.but then why pushover curves in both direction are different.
What about the hinges' model? Is the constitutive model diagram of your P-M2-M3 hinge symmetric?
Check then the default diagram if it is symmetric.If you have rectangular sections it should not be symmetric in both directions.
By the way I forgot to ask you, did you perform the nonlinear analysis on the model that you've posted here?If this is the case then it is evidently natural to get different results.
I have posted vertical irregular building.but nw i m talking about one regular building.
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