I believe the current version of SAP2000 explicitly calculates this and you may find them as output option in printing results to file. If not, then the following CSI knowledge base link may help:

https://wiki.csiamerica.com/display/kb/Mass+participation+ratio

hi Timothy Huff , thanks for you reply.

My doubt is that modal mass coefficient and participation factor as per ATC 40 are unitless values. As you said in SAP2000 display tables, it gives the participation factors which is true but it is not unit less. I need to find the values as per ATC 40.I am attaching the image of those formulas. Can you suggest me how to retrieve that information from SAP2000

Dear venkatesh. the link of timothy simply show's what you asked for. In the link the following could be found.

((The fixed-mass participation ratio may be calculated as follows:

Export the Joint Masses table to Excel by selecting Analysis Results > Joint Output > Joint Masses.Sum all joint masses to find the total mass.Square the Participation Factor table and divide this value by total mass. ))

And so after dividing by the total mass the factor will be unitless. Thank you all

Hi Muhammad S. Elfeky , thanks for your reply.

am not getting the correct answer when I did as per your suggestion. Also suggest me how to get those factors directly from SAP to find the spectral coordinates.

Am attaching my doubt with values,please check it

Dear venkatesh

Simply if you clicked the file menu then the export then sap2000 MS Excel spread sheet.xls file then structure output then modal information then modal participating mass ratio and you will get the unitless ratio directly. Many thanks.

Hi Muhammad S. Elfeky ,

The unitless ratio which you have defined in the last answer. Is it Aplha1 or PF1 as per ATC 40 which I shared in my first answer.

CAn you explain how to get the other also. Actually i have the pushover curve load vs displacement. I need those factors to convert pushover curve to spectral coordinates.

Please help me with this. Thanks

Dear venkatesh

Most probably it will be the alpha 1. But sorry that I m not that much aware with the ATC 40. My answer is based on the general knowledge regarding your question. Thank you and I hope you find your required answer from someone who has a good knowledge with the ACT 40. Best of luck

Thank you Muhammad S. Elfeky for your suggestions.