The feature that you are looking for requires a program in which the stress strain relationship beyond the onset of yielding can be modeled. Typically only high end non-linear analysis programs have this capability. STAAD being a program primarily for modeling structures whose deformation in the linear elastic range is not a appropriate tool for modeling plastic hinges.

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The pushover analysis implemented in STAAD.Pro is based on the assumption that first mode of the structure is the fundamental (predominant) mode of vibration of the structure. Thus the analysis (implemented so far with this assumption) is valid for those buildings whose first mode has highest/higher mass participation in the lateral loading direction.

Also, as per Section 3.3.3.2.3 of FEMA356:2000 code (Chapter 3), lateral distribution of base shear is possible only when 75% of total mass participates for the fundamental mode in the specified direction of lateral load generation.

If you believe that your model satisfies this condition, you may try doing a pushover analysis. You can test it by asking the program to calculate the first 6 frequencies and viewing the ANL file to see what the participating factors are.

Also, the pushover analysis is part of the Advanced analysis engine, not the standard analysis engine. You need to ensure that you have the license for the advanced analysis engine.

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Thanks a lot for the value adding input and I am very sorry for the late response.

I am going throught the Pushover analysis steps to be followed in STAAD Pro. The eligibility criteria to do Pushover analysis is adequate for my structure (mass participation for the fundamental mode is 85%). So, I am going ahead with the analysis. I have some queries which I think you can help me on.

(1) In Define Input section, I would like to choose the Member Specific Parameters. There are parameters called Ky and Kz (effective length factor for beams). As far as I know Ky and Kz are the effective length factors to determine axial capacity of the member. Is there any other interpretaion involved for Pushover analysis?

(2) Is there any mehtod by which I can specify that the hinge formation in beam should occur at certain distance from support?

Thanks for making it clear that it's advance analysis and I need to ensure for the appropriate license.

Best Regards

Himali

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(1) In Define Input section, I would like to choose the Member Specific Parameters. There are parameters called Ky and Kz (effective length factor for beams). As far as I know Ky and Kz are the effective length factors to determine axial capacity of the member. Is there any other interpretaion involved for Pushover analysis?

Ans - Effective length factors serve two purposes in Pushover Analysis.

a) These factors are used in calculating Euler Buckling Load. This is checked against the member axial compressive force. If the compressive axial force is more than that of the Euler load the member is assumed to have failed and is removed from the structure for further analysis.
b) If the member passes the check against Euler buckling load then it is considered for hinge formation. For that these factors are again used for finding the axial capacity for member.

(2) Is there any mehtod by which I can specify that the hinge formation in beam should occur at certain distance from support?

Ans - There is no method where user can specify the location of hinge formation. Total number of 13 sections are scanned along the length of the beam for bending moment about major and minor axis. Maximum B.M is located and checked against section capacity of the beam. If sectional force exceeds section capacity the material starts yielding at that particular location and hinge starts to form at that location.

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