Modelling of 25 storey building with the specified properties using ETABS

Aim:- Check the building response for seismic force in both x and y direction by analysis and model the 25 building storey building with specified storey in ETABS

Introduction:-

Seismic force :- It is the external force applied to the structure as a result earthquake generated agitation

• In this the earthquake occured at once in a 2500 years
• Seismic cannot be determined it's a less uncertainity
• Seismic force occure at the ground level in all the directions and it has 3degree of freedom they are 2 translational and 1 rotational force
• The base shear starts at the bottom of the buildings when the seismic load occures

ETABS :-

• The full form of ETABS is Extended three dimensional analysis of building system
• ETABS software was started by CSI (Computers and Structural ,Inc
• ETABS is a engineering software which is used for multistorey analysis and design
• In this software we can analyse and design the seismic load, wind load, and other loads
• In this software we are defining and assigning the materials, frame sections, slab sections diaphragm etc.,
• This software give the proper output result to that analysed model

Procedure:-

Step1:-

• Open the ETABS software by double clicking on it
• Then click on the new model option which is at left side of the screen

Step2:-

• After click on the new model then model initialization dialouge box will open
• Select the use built in settings with
• Set the unit as metric, database as Indian, Steel code book as IS 800:2007 and Concrete design code as IS 456:2000
• Then click on OK

Step3:-

• After completion of model initialization then New model Quick template dialouge box opens
• Select the custom grid spacing and custom storey data and then edit accordingly

Step4:-

• Mention the Grid spacing for the both x and y direction
• The spacing of storeys are 4m offset
• Then click on OK

Step5:-

• After editing the Grid spacing then select the Storey data then edit that
• Click on the edit storey data to edit the stories

Step6:-

• Click on the storey 2, then click on the right button of your mouse
• Then click on the add storey then click on the keep existing storey heights

Step7:-

• After that add storey dialouge box opens
• Then change the number as 22 because we require 25 number of stories, here 2 stories are already assigned
• Then click on OK

Step8:-

• Change the storie 3 to 25 as a similar storey
• Then click on OK
• Here there are 25 stories for the building
• Height of the building should be 3m
• Stories in the table are Base, Plinth, Storey 1 to Storey 25
• Make the Storey 1 as a Master storey and Make the Storey from 2 to 25 as a similar to

Step9:-

• After completing all the grid lines and storey data
• Click on the OK

Step10:-

• This is the how the structure looks like after completing all the information
• Here the plan view and 3D view are shown in this software in one screen

Step11:-

• After completing all the settings define the materials and define the sections for the column, beam and slabs
• Click on the define and select the material properties
• Click on the new material to create a new material
• Select the required properties of the material
• Region as India, Material type as concrete, Standard as Indian, Grade as M-30
• Then click on OK

Step12:-

• Click on the new material to create a new material
• Select the required properties of the material
• Region as India, Material type as Rebars, Standard as Indian, Grade as HYSD Grade 415
• Then click on OK

Step13:-

• To define a section properties
• Click on the define, then click on the section properties, then select on the frame section

Step14:-

• After selecting the frame section
• Click on the add new property to create a new frame section
• Select the rectangular concrete for the beam then click on OK

Step15:-

• After clicking on OK then frame section property data dialouge box opens
• Change the property name as Beam 300x400, Change the material as M-30, Change the dimensions
• Click on the modify/show Rebars to get more

Step16:-

• After opening the modify/show Rebars then this dialouge box opens
• Select the M3 Design only (Beam)
• Then change the longitudinal and Confinement bars as HYSD 415
• Then click on OK

Step17:-

• Select the frame section
• Click on the add new property to create a new frame section
• Select the rectangular concrete for the column then click on OK
• After clicking on OK then frame section property data dialouge box opens
• Change the property name as Column 800x800, Change the material as M-30, Change the dimensions
• Click on the modify/show Rebars to get more

Step18:-

• After opening the modify/show Rebars then this dialouge box opens
• Select the P-M2-M3 Design (Column)
• Then change the longitudinal and Confinement bars as HYSD 415
• Then click on OK

Step19:-

• To create a slab
• Click on the define then select the section properties then click on slab sections

Step20:-

• After selecting slab section the slab properties dialouge box opens
• Then click on the modify/show properties to change the properties

Step21:-

• Change the property name as Slab 150, change the slab material as M-30, and change the slab thickness
• Then click on OK

Step22:-

• To define the load pattern
• Click on the define then click on the load pattern

Step23:-

• Add the load patterns
• Dead load, Live load, Wall load, Seismic load in both x and y direction
• Mention the code book for the seismic load

Step24:-

• Click on the seismic load in x- direction then select the modify lateral load
• Except X dir uncheck all the direction andd eccentricity
• Change the seismic zone factor to 0.16

Step25:-

• Click on the seismic load in y- direction then select the modify lateral load
• Except Y dir uncheck all the direction andd eccentricity
• Change the seismic zone factor to 0.16

Step26:-

• After making all the settings in the load pattern
• Click on OK

Step27:-

• To define the mass source
• Click on the define then click on the mass source

Step28:-

• After selecting mass source then mass source data dialouge box opens
• Check only the specified load patterns
• Select the load patterns of dead load of 1 multiplier, live load of 0.25 multiplier, wall load of 1 multiplier
• Then click on OK

Step29:-

• To define the load cases
• Click on the define then click on the load cases
• All the load are automatically selected
• Then click on OK

Step30:-

• To define the load combination
• Click on the define then click on the load combination
• Select the default combination
• Then click on the concrete frame design and convert to user combination
• Then click OK

Step31:-

• After selecting the concrete frame design
• All the load combinations are automatically appears here
• Then click on OK

Step32:-

• Draw the column at the junction of the grid lines
• Click on the Quick draw column icon in the tool bar

Step33:-

• Ensure that it should be the column property
• The size of the column should be 800x800mm

Step34:-

• Place the mark at the junction of the grid lines
• Then the column will appear at the junction

Step35:-

• Draw the beam along the junction of the grid lines
• Click on the Quick draw beam/column icon in the tool bar

Step36:-

• Ensure that it should be the beam property
• The size of the beam should be 300x400mm

Step37:-

• Place the mark along the junction of the grid lines
• Then the beam will appear along the junction

Step38:-

• Draw a slab in the model
• Select the Quick draw floor / wall to draw the slab

Step39:-

• Ensure that the selected property is slab 150
• The 150 reffers to the thickness

Step40:-

• Select the similar storey
• Click on the region to place the slab
• This is how the slab look like

Step41:-

• To select the frame section
• Click on select then click on select then click on properties then select the frame sections
• Then select all the beams

Step42:-

• Assign the loads for the frame element
• Click on the assign then click on the frame load then click on distributed

Step43;-

• To select a slab section
• Then select a assign then go to shell load then select a distributed
• Select the load pattern as wall load
• Then take a uniform load as a 10 KN/m
• Then click on apply then click on OK

Step44:-

• After applying the 10 KN/m load
• The load assigned to the beam is shown as below

Step45:-

• To select the slab section
• Click on select then click on select then click on properties then select the slab sections

Step46:-

• To assign the loads to the slab
• Click on the assign then click on the shell load then click on uniform

Step47 :-

• Select the load pattern as live
• Then take a uniform load as a 3 KN/m
• Then click on apply then click on OK

Step48:-

• To provide the diaphragm
• First select the slab section
• Click on assign then click on shell then click on diaphragm

Step49:-

• The diaphragm dialouge box opens
• Then select the diaphragm assignment as D1
• Then click on apply then click on OK

Step50:-

• At last Run the analysis by clicking the Run analysis button or by clicking F5
• Give a time for analysis then it will give a result of it

Result:-

This is the snap shot of buidling undergo seismic action and also deflection in both x and y direction

Comaprision of time period for the building model

Criteria		Desirable solution	Exercise result
Fundamental translational natural period	X - Direction	4.4 s	4.85 s
	Y - Direction	4.2 s	4.65 s
Torsional irregularity	IS 1893-2016 (Part 1) Table 5	Torsional mode time period should be lesser than X and Y direction time period	Yes (3.6 s)
Vertical irregularity	IS 1893-2016 (Part 1) Table 6 Clause 7	First three mode together should contribute at least 65% in mass participation factor in each principal direction	Yes (In the first mode only it occupies the 85%)
		Fundamental lateral natural periods in two principal plane directions are away from each other by at least 10%	No (If we deduct the 10% then we will get a answer as 3.37 but the mode 1 and mode 2 almost same)
Inter storey drift	IS 1893-2016 (Part 1) Clause 7.11.1.1	Storey drift shall not exceed 0.004 times the storey height for the base shear with no load factor (4x10^-3)	Yes (The storey drift in EQx we get near 1.35 and in EQy we get slightly greater than 1.35)