Modelling of 25 storey building with the specified properties using ETABS

AIM

Model a 25 storey building on ETABS with structural properties as specified below. 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.

Structural Element Sizes

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

Material Properties

• Grade of Concrete : M30
• Grade of Steel Reinforcement Bars : Fe 415

Loading

• Dead Load on beams from infill wall : 10 kN/m (Let us assume the same for roof floor in view of parapet)
• Live load on floor : 3 kN/m2 (Let us assume the same for roof floor)

a) Buildings are assumed to be pinned at the base

b) All columns in all storey are of the same size

c) All beams in all storeys are of the same size

d) Building is located on Soil type-II and in Zone-III. Assume other factors if required.

INTRODUCTION

ETABS is an engineering software that is used for multi-story building analysis and design. Modeling tools and templates, code-based load prescriptions, analysis methods and solution techniques, all coordinate with the grid-like geometry unique to this class of structure.

Here we are modeling and analyse a 25 storey building using ETABS

PROCEDURE

Step 1:Open ETABS software

Open a new model

Step 2:Select Custom grid spacing

Select ‘edit grid data’

Step 3:Select story data

Select edit story data

Step 4:Select story 3-right click -select add story-keep existing story height

Step 5:Select story 1 make it master story

Make all other stories similar to story 1

Step 6:From define tab select material property

Add M30 concrete and HYSD415 rebar

Step 7:From define tab select section properties

Then select Frame sections -Add new sections

Add columns and beam

Step 8:From define tab select section properties

Select slab sections

Add new property

Add slab properties

Step 9:Select define

Select load patterns

Add load patterns

Step 10:Select define

Select mass sources

Add mass and mass multipliers

Step 11:From define select load cases

Step 12:From define select load combinations

Add load combinations

Step 13:Select quick draw columns

Select all stories

Select the column size

Step 14:Select quick draw beams

Select all stories

Select the beam size

Step 15:Select the master story(story 1)

Select similar story

Select Quick draw floor

Step 16:From select option-properties-select beam

Select all beams

Step 17:From assign tab-select frame load-distributed

Assign load to beams

Step 18:Assign -select shell load -select uniform

Step 19:Select all slabs

Assign-shell-Diaphragms

Step 20:Select ‘Run analysis’

RESULT

From model explorer window select tables-Analysis-Results-Model Results

Select the needed results

Model periods and frequencies

Model participating mass ratios

Story response plot(maximum story drifts)

The value for maximum drift for EQX is .0007 and EQY is between .00085

Criteria		Desirable Solution	Exercise Result
Fundamental Translation natural period	X- direction	4.4 second	4.416
	Y-direction	4.2 second	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-storey Drift	IS 1893-2016(Part-1) Clause-7.11.1.1	Storey drift shall not exceed 0.004 times storey height for base shear with no load factors (4x10-3)	Yes