To determine whether a column is a no sway or a sway column, stability index Q may be computed as given in annex-e of IS456. It's a very time consuming and cumbersome calculation while we are freezing the column sizes. if Q is directly calculated by Staad it may help user a lot. Apart from Q in this we have to calculate the value of Beta for beam and column which depends upon the flexural stiffness for column and beams, which can be time-consuming. To simplify this process, consider using software tools that automatically determine Beta based on member properties and boundary conditions. so,
Displaying Q in Design Data:
Including the stability index Q directly in the design data would enhance transparency and facilitate decision-making during the design process.
By having Q readily available, engineers can make informed choices regarding sway conditions and column behavior.
Customization of Direct Calculation:
Providing customization options for direct calculations (such as Q) within the software would empower users.
Engineers could adjust parameters, load combinations, and other factors to suit specific project requirements.
The idea of determining the lateral load at a level using the shear at the ends of members rather than the applied load has potential, although challenges would still apply as the application would need to account for all members that have a start or end node at the given storey height, AND have their other node at a greater y ordinate (to eliminate any lower level column and horizontal beams) AND resolve both shear and axial forces in any diagonal members. The displacement and resulting value of Q might then be determined for each considered member. However I agree this might need to be done as commands for each storey. Therefore the instruction might be along the lines of IS456Q Height StoreyHt, for which it calculates and reports Q for the members who have a node with a Y ord at the given Height value (or Z ord if using Z UP) and for a storey height given. If a member does not span the full storey height, the displacement for sway is prorated. This idea will be added to the backlog.
I wanted to express my gratitude for your prompt response regarding this issue.
After further consideration, I believe that determining lateral loads in each story can indeed be approached by aggregating the shear forces acting on all columns in a particular direction. This approach is analogous to how we handle earthquake load cases, where the total shear acting on the mass source becomes the lateral load.
To summarize:
Shear Forces: Sum up the shear forces in all columns along the intended lateral direction (e.g., X or Y axis).
Total Lateral Load: The cumulative shear force represents the lateral load acting on the structure.
Story Drift: The corresponding story drift (lateral deflection) can then be calculated based on this total lateral load.
Additionally, if specific data such as story height etc is required for accurate calculations, manual input can be incorporated into the analysis.
Thank you for posting this idea. This is indeed an interesting proposal. As you know, the calculation of Q in IS456 is dependant on identifying a number of values namely sum of axial loads on all columns in the story in which the selected column resides, the lateral force applied within the storey and the height of the storey itself. Remembering that STAAD is free form, being able to determine storeys is not a trivial task. The program can infer storeys when the model includes the definitions of rigid diaphragms. So we can use that to determine storey heights. The major challenge though is to determine the lateral load at each storey. If storey 1 goes from 0.000m to 4.000 m and storey 2 goes from 4.000m to 8.000m, a lateral load at a node at 4.000m considered a lateral load on storey 1 or storey 2?