Use of eccentricities values to counter the torsion in ETABS.

[M_U]

Hi,
We have a building in which we have first mode as torsion mode. One of colleagues is saying that instead of correcting the geometry like adding shear walls or changing column orientation, we should find the eccentricities at diaphragms and use those increased values in the load patterns. I am sure that this is not a correct approach, but can some shed light on this. My reference code is ASCE 7-16. The torsion happens due to the difference between the center of rigidity and mass. So he is arguing that we can use the increased eccentricities value to bypass the correction of first torsion mode. I need an counter argument for this approach.

Thanks

 

[Luceid]

I am not sure what you are tryin to achieve here. Can you provide an image of the building itself, as in some cases, torsion could very well be the first mode.

 

[human909]

I think his colleage is trying to 'cheat' his way around the torsion induced by "the difference between the center of rigidity and mass".

A novel approach. Ignore the realities of your structure and just adjust the number to make it work.... I've tried the same thing with my paper-mache highrise. I couldn't get it to work until I found this "one neat trick" that the corporations in steel and concrete don't want you to know. If you increase the E and yield stress of paper-mache by two orders of magnitude every thing works well and no need for steel or concrete!

I'm sure my high-rise would have been revolutionary had the workers not screwed up. They didn't put the façade on early enough and the rain came along...