I am doing a case study comparing the fundamental period of a 20-story reinforced concrete building with dual system in both directions and compared the results from SAP 2000 and Midas Gen. The reference building is from the book of SK Ghosh Seismic Design using Structural Dynamics. here is the link of the book http://secure.skghoshassociates.com/product/show_book.php?isbn=9781580017485.
The example problem in the book is solve by the author manually and the modal analysis was done using SAP 2000 and I wanted to verify the accuracy of the result by comparing them with midas gen and staadpro, Midas Gen result is very close with the book's output within 1 to 2 % difference however, staadpro output is way off, Here is the tabulated result,
Here is the final result of the case study that I am doing. Staadpro yield a close agreement with SAP2000 and Midas Gen.
SAP 2000 3D MODEL MIDAS GEN 3D MODEL STAADPRO 3D MODEL (Plate Modeling Method) MODE PERIOD MASS PARTICIPATION PERIOD MASS PARTICIPATION PERIOD MASS PARTICIPATION1 2.485 71.2% 2.418 72.19% 2.390 72,94% 2 0.659 14.8% 0.658 14.19% 0.657 14.24%3 0.300 6.1% 0.308 5.98% 0.316 5.87% 4 0.178 3.1% 0.184 3.16% 0.200 2.76%
I am still exploring the orphan node method in staadpro, I believe the plate modeling is more accurate.
Many thanks for the explanation Kris.
The images below are coming from Midas Gen and Staadpro,