Modelling of 25 storey building with the specified properties using ETABS

Aim:

To model a 25 storey building on ETABS with ground floor or plinth floor level can be taken at a height of 1.5 metres from the base. Each of the successive 25 storeys has a storey height of 3 metres.

Procedure:

i.Initial step is to create the grid using custom grid spacing option according the structural elements. Using custom story height, change the first story into plinth of height 1.5m and all the remaining story height as 3m. Add the story using keep the existing story height apply the height and No. of story required and rename them.

ii.Keep the story 1 as master story and make the remaining stories into similar to story 1. Create the Material properties from Define menu.Create the concrete as M30 and Steel as HYSD 415. Create the Beam size as 300mm x 400mm where 400mm as depth and 300mm as width. Create the column dimension as 800 mm x 800 mm. Create the slab properties and keep the modelling type as membrane because to eliminate the flange behaviour.

iii.Create the load pattern (Wall as super dead load and EQX, EQY as seismic loads). In mass source, Mass multiplier for load patterns, assign Dead load as 100%, Live load as 25% and Wall load as 100%. From load combinations, select the concrete frame design.

iv.From quick draw option draw the columns, beam and slab secions. Before applying slab sections, keep it in story 1 and change to similar stories.

iv.From select option, select the beams and assign the wall load as 10KN/m and in slab sections assign the live load as 3 KN/m. Add diapharms to the slab sections.

v.After assigning the loads, save the modal and analysis the modal. Once the analysis is completed, from the analysis table the following results are obtained.

Criteria		Desirable Solution	Exercise Result
Fundamental Translational Natural Period	X - direction	4.4 Seconds	4.416
	Y - direction	4.2 Seconds	4.222
Torsional Irregularity	IS 1893-2016 (Part-1) Table-5	Torsional mode, Time period should be lesser than X and Y direction time periods	Yes
Vertical Irregularity	IS 1893-2016 (Part-1) Table-6 Clause-7	First three modes together should contribute at least 65% in mass participation factor in each principal direction	Yes
		Fundamental lateral natural periods in two principal plane directions are away from each other by at least 10%	No
Inter-story Drift	Is 1893-2016 (Part-1) Clause-7.11.1.1	Story drift shall not exceed 0.004 times the story height for base shear with no load factors (4x103)	Yes

Result:

The modelling of a 25 storey building on ETABS is completed and all the exercise reults are related with the desirable solutions.