Modelling of 25 storey building with the specified properties using ETABS

• Given Data:-

Structural Element Sizes

• Beams: 300 x 400 mm
• Columns: 800 x 800 mm
• Slab: 150mm thick

Material Properties:

• Grade of Concrete: M30
• Grade of steel Reinforcement bars: Fe415

Loading Details:-

• Dead Load on beams from infill wall: 10kN/m (Let us assume the same for floor in view of parapet).
• Live load on floor: 3kN/m^2 (Let us assume same for roof floor)

1. Buildings are assumed to be pinned at the base.
2. All columns in all story are of the same size.
3. All beams in all storeys are of the same size.
4. Building is located on Soil type-II and in Zone-III. Assume other factors if required.

Aim:-

To model a 25-storey building using ETABS software and verify the seismic code requirement from ETABS analysis.

Procedure:-

• Open ETABS software.
• Click New Model.

• Give model initialization setting as follows.

• Click OK.
• In the new model quick template dialogue box, select custom grid spacing and click Edit grid data.

• Give the following settings in grid system data dialog box.

• Click ok.
• Select custom story data under story dimension and click edit story data.

• Give the story data for first-three story as follow having story 1 as master story.

• Write click on the first column and select add story and click keep existing story heights.
• Give number of added story as 22.

• Click Ok.

• Click Define -> Material properties.

• Select Add new material in the dialog box concrete and reinforcements as shown in image below.

• Select the concrete shape as rectangular and give the following settings for the Beam.

• Click on Modify/ Show Modifiers.

• Repeat the same for columns with the parameters given in the question.

• Column property is added.
• Click -> Section Properties -> Slab Section.

• Select Add New Property and give the following settings.

• Click Define -> Load Patterns.
• Define Load Patterns by its name.

• Click Define -> Mass Source

• Check load cases by click Define -> Load Cases.

• Create Load Combination, Define -> Load Combinations.

• Create Columns using "Quick Draw Column" tool.

• Select "Quick Draw Beam" tool.

• Select First Floor in Plan View.

• Draw slab using quick slab by having similar stories in the status.

• Select all the beams from select tab.
• Assign frame loads as distributed from assign tab.

• Select the slabs from select tab and assign as diaphragm from assign tab.

• Click run analysis in the panel after saving the file.

Result:-

Criteria		Desirable Solution	Exercise Result
Fundamental translation natural period	X - Direction	4.4 Seconds	4.41
	Y - Direction	4.2 Seconds	4.22
Torsional Irregularity	IS 1893-2016(Part - I) Table - 5	Torsional mode time period should be lesser than X and Y direction time periods	Yes
Vertically Irregularity	IS 1893-2016(Part - I) Table - 7 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 away from each other by at least 10%.
Inter-Storey drift	IS 1893-2016(Part - I) clause - 7.11.1.1	Storey drift shall not exceed 0.004 times the storey height for base shear with no load factor (4x10^-3)	Yes

• Click Display -> Story response plot. Change the display type to maximum storey drift and desired combo to see the plots.