I analysed attached structure in STAAD pro. When I design this structure columns3808.Structure 1.std with RCDC the effective length factor for columns is very much high even upto maximum value of 5. Why?
1. Is there is any error in modelling in STAAD pro?
2. Is there I am making any mistake in RCDC?
Please suggest
Hi
Effective length factor is calculated as per Annex E of IS 456. it is depend upon the whether the story is Sway or Non-Sway. Qualification of Sway / Non-Sway frame is depend on the various factors like Drift , Axial load, Story height and Story shear. when story is Non-Sway, the effective length factor is less than 1 . but for the Sway frame, the effective length factor can go up to infinity. RCDC has restricted to 5 considering particle case. Beta factor also plays an important role calculating effective length factor, which is depend on the column and beam stiffness meeting at that joint.to control the effective length factor, user can increase the stiffness to control excessive deflection.RCDC allows to modify the effective length factor as per user choice. refer below sample validation problem for effective length factor calculation,
Sway calculation_IS 456
https://communities.bentley.com/products/ram-staad/w/structural_analysis_and_design__wiki/42005/is-456_5f00_column_5f00_effective-length-factor-as-per-sway_5f00_non-sway-frame