Drastic change in all column reinforcement if I change the depth of 1 beam

[Prk_B]

Hi everyone,

I'm modelling a G+2 building as per IS 456:2000, IS 1893:2016 and IS 875:2015 Part 3.
Data Considered:
Seismic Zone - III
Importance Factor - 1
Response Reduction Factor - 3
Site type -2
Framing Type -Ordinary Frame

Basic Wind Speed - 39 m/s
Importance factor -1
Risk Coefficient - 1
Topography - 1
Terrain Category - II

If I change the depth of either one of the highlighted beams (refer to the attached screenshot) from 15" to 18" or from 18" to 24" in the plinth, it results in reinforcement changes in all 48 columns of the model on the ground floor. I have even tried remodeling and only considered gravity loads, but the result is the same.

I don't know where I went wrong, so I'm requesting one of you to review my model and check whether it's correct or not. Please also try changing the depth of either one of the highlighted beams (refer to the attached screenshot) and observe the differences in results. What could be the possible error? Please help me with this.

I've attached a few screenshots, as well as the e2k and edb files of my ETABS model. Please find the attachments.

Thank you

Link

Link

[URL unfurl="true"]https://res.cloudinary.com/engineering-com/raw/upload/v1703759753/tips/1._MODEL_njgp34.e2k[/url]

[URL unfurl="true"]https://res.cloudinary.com/engineering-com/raw/upload/v1703759755/tips/1._MODEL_kvrwnr.EDB[/url]

 

[dik]

It's been years since I've done any serious concrete high rise stuff... some possible suggestions:

Why so many changes in beam depth; the economy is not likely there, in particular when framing into a column. 18 could be a 12" or 16" (forming) and a 6" slab. There are a few instances where a 15 (units) deep beam should be 18 based on tributary area.

The beams shown skewed avoid a serious torsion issue that is not likely possible with a 15 beam.

My $0.03CAN.



-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[TLHS]

I don't have etabs here, but presumably, you're seeing everything change because you've got a design group of some sort set up and one of the columns local to one of those beams is driving design and governing.

It could be a code detailing issue as well, like is the program trying to enforce strong column weak beam hinging.