www.sefindia.org

[subha_mukherjee]

In a building some of the columns are taken as gravity column. In such case how can we make the detailing of such gravity columns?How can we assign gravity column property to those columns in the structural model?
                                                                           Regards,
                                                                            Subhajit M

[vikram.jeet]

Gravity Columns :

As name indicate, these columns carry only Gravity Loading  (Vertical floor loads) but are treated as REDUNDANT for sharing Horizontal forces due to EQ.

However as per spirit of IS 1893 ,, these are  still to be designed for some MINIMUM EQ Horizontal force, even though Entire EQ is shared by other members viz Shear walls and other Full columns.

Not a computer / software savy - my remarks on modelling could be treated as tiny tot play :-
Model 1 - Treating Gravity columns redundant for Horizontal forces
Model 2 - Treating Gravity columns capable to share Minimum 33% to 40% Horizontal force

Model 1 to be used for Shear wallsvand other Full columns design
Model-2  to be used for Gravity columns design

Detailing - Needs to be  structurally monolithic

[vikram.jeet]

DETAILING OF GRAVITY COLUMNS SHALL BE DONE AS  MONOLITHIC AS ALREADY SAID.

BUT IN ADDITION, DUCTILE PROVISIONS MUST BE INCORPORATED AS PER NORMAL FULL COLUMNS.

The idea is that during severe EQ Event, these columns may  yield but do not suffer high P- Delta effects and  Gravity -columns are saved from Local collapse. Even though Structural system of Shear wall and Full columns capable of global strength .

[sakumar79]

[vikram.jeet]

I think Single Model with different load combinations can be used if design of reinforcement is worked out Manually based on specific Load combination for Gravity Columns,,

But, now a days,, Analysis and Design are done by software based in critical Load combination sorted out by software. In that case, probably, I feel it may need two models, ,

[vikram.jeet]

Yes in Single Model :-

One can get results of design reinforcement for a specific load case .

Hence I feel we can tackle Results ( output)  file in two  different files on Single model
One for Shear walls and Full columns on Load combination s  related to these.
Other output file for Gravity columns based on Load combination for it.

Those handling softwares can further say,,

Thanks Er Arun Kumar ji for extending the discussion  putting more light on topic.