Structural Modelling using Etabs 2018

Aim:- 

Introduction:- 

Procedure:-

Data required for ETABS 

• Pinned support, Base + 9 storey (Ground to terrace), + Mumty level
• Column size 450x600mm, Beam 400x500mm, Slab 150mm thick and Shear wall 300mm thick 
• Live load 2.5KN/m^2, Floor finish load 1.5KN/m^2, Wall load 5KN/m, Water tank 20K liters over mumty equivalent to 200KN over all load

Conceptual design consideration

• Re-entrant and cutout check and modification (Compromise)
• Vertical irregularity (Soft storey)
• Planar irregularity (Look symmetrical)
• 2% Shear wall area with respect to building area (8m^2)

                       According to code book we should give 2% Shear wall area 

                       The building area is 391.05 Sqm =approximately = 400 Sqm

                                    400x(2/100) = 8 Sqm shear wall

                         L x thickness of Shear wall = 8m^2

                         L x 0.3 = 8

                         L = 26.6 = 27m

                         Length of the Shear wall = 27m

• Stiffness modifier for Column, Beam and Shear wall (0.35 for Beam, 0.7 for Vertical)

 

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 0m, 6.4m, 13.35m, 19.95m offset in A to D Grids
• The spacing of storey are 0m, 4.95, 8.35m, 11.45m, 14.85m, 19.8m offset from the 1 to 6 Grids
• 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
• Click on the storey 4, then click on the right button of your mouse 
• Then click on the add storey then click on the keep existing storey heights 
• After that add storey dialouge box opens 
• Then change the number as 5 because we require 5 number of stories, here 4 stories are already assigned
• Then click on OK
• Change the numver of added stories 5 as a similar storey
• Then click on OK

 

 

Step6:- 

• 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

 

 

 

Step7:- 

• 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

Step8:- 

• 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

 

 

Step9:- 

• 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 500
• Then click on OK

 

 

 

Step10:- 

• 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 450x600, Change the material as M-30, Change the dimensions 
• Click on the modify/show Rebars to get more

 

• Change the Longitudinal bars as HYSD 500 
• Change the confinement bar ass HYSD 415

 

Step11:- 

• To define a section properties
• Click on the define, then click on the section properties, then select on the frame section 
• 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
• After clicking on OK then frame section property data dialouge box opens 
• Change the property name as Beam 400x650, Change the material as M-30, Change the dimensions 
• Click on the modify/show Rebars to get more

 

Step12:- 

• After opening the modify/show Rebars then this dialouge box opens 
• Select the M3 Design only (Beam)
• Then change the longitudinal as HYSD 500 and Confinement bars as HYSD 415
• Then click on OK

 

Step13:- 

• To create a slab
• Click on the define then select the section properties then click on slab sections
• After selecting slab section the slab properties dialouge box opens 
• Then click on the modify/show properties to change the properties
• Change the property name as Slab 150, change the slab material as M-30, and change the slab thickness
• Then click on OK
• This slab is used for the Slab stairs

 

Step14:- 

• To create a slab
• Click on the define then select the section properties then click on slab sections
• After selecting slab section the slab properties dialouge box opens 
• Then click on the modify/show properties to change the properties
• Change the property name as Slab 125, change the slab material as M-30, and change the slab thickness
• Then click on OK

 

 

 

Step15:- 

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

 

 

 

Step16:- 

• To create a Shear wall 
• Click on the define then select the section properties then click on wall sections
• Then change the property name as Wall 300mm, Change the wall material as M-30, Change the modeling type as   Shell-thin and Change the thickness as 300mm
• Then click on OK

 

Step17:- 

• 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 0.36

 

 

Step18:- 

• 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 0.36

 

 

 

Step19:- 

• 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

 

Step20:- 

• 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 concrete shear wall design then click on convert to user combination
• Then click OK

 

Step21:- 

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

 

Step22:- 

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

 

Step23:- 

• After drawing all the columns then change its orientation
• Go to the assign then go to the frame then go to the local axes 
• Then the Frame assign ment dialouge box opens 
• Then select the rotate by angle and give the angle as 90 degree
• The column will orient

 

 

Step24:- 

• This is the how the column placement after changing the orientation of the column
• Make sure the required column is oriented correctly

 

Step25:- 

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

 

Step26:- 

• Select the grid in which you required the beam
• Select grid where the column connection occured

 

Step27:- 

• After drawing a primary beam then draw the secondary beam compared to the given floor plan
• After drawing the seconddary beam then draw the balcony are by using a beam ( To draw like this comapre the floor plan which is given in the question)
• Use a divide option to divide the beams

 

Step28:- 

• Use a Replicate option to replicate the beam 
• Here we can use replicate or mirror option 

 

 

Step29:- 

• Use a Quick draw wall option to draw the wall
• Here the wall is northing but a Shear wall which resist the lateral force

 

Step30:- 

• This is the snap of shear wall 
• The shear wall is provided at the corners of the building, stair case and lift core and passage of the building 

 

 

Step 31:- 

• To create a slab
• Click on the define then select the section properties then click on slab sections
• After selecting slab section the slab properties dialouge box opens 
• Then click on the Slab 150mm for stair and 125mm for building

 

This is the stair slab

 

 

 

                                                        This is the building slabs

 

 

 Step32:- 

• Make the base as fixed to make this fixed support
• Go to the base level then select all the points 

 

Step33:- 

• After selecting all the base points then click on assign then go to the joints
• After selecting the joints then go to the Restrained 

 

Step34:- 

• After selecting the Restrained then joint assignement dialouge box opens 
• Then click on the fixed then click on apply then click on OK

 

 

Step35:- 

 

• 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 3.5 KN/m
• Then click on apply then click on OK
• After applying the 10 KN/m load 
• The load assigned to the beam is shown as below

 

 

Step36:- 

• To assign the loads to the slab
• Select the where you are gooing to asssign the load
• Click on the assign then click on the shell load then click on uniform 

 

Step37:- 

• Select the load pattern as live
• Then take a uniform load as a 2 KN/m for the all rooms and kitchen
• Then click on apply then click on OK

 

 

 

Step38:- 

• After assining all the loads take the live load reduction factor into acccount
• Click on the design then click on the live load reduction factor 

 

Step39:- 

• After selecting the  live load reduction factor then its dialouge box opens 
• Then click on user define then click on the define option to give the  live load reduction factor 

 

Step40:- 

• Live load reduction factor is depend on the storey
• From 1st to 2nd Stories take reduction factor as 1 then reduce 10% up to 6th story
• From the 6th story till story 9 keep the  live load reduction factor as 0.6 only
• Then click OK
• Now the  live load reduction factor is taken into account

 

 

Step41:-

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

Step42:- 

• 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

 

 

Step43:- 

• To use the Response spectrum
• Go to define and then go to function then go to the Response spectrum

 

 

 

Step44:- 

• After clicking on the Response spectrum 
• Then the define response sepctrum fuction dialouge box opens
• Then click on Add new function

 

Step45:- 

• After clicking on the Add new function 
• Then change the name of the function name
• Then Click on OK 

 

Step46:- 

• After this assign the response spectrum in x and y direction
• Go to define then go to the load cases then click on Add new case

 

Step47:- 

• Give the load case name as RSx, then load case type as Response spectrum
• Then click on the add button
• Change the load name as U1 (x - direction) function as IS function, keep the scale factor as it is
• Then click on OK

 

 

Step48:- 

• Give the load case name as RSy, then load case type as Response spectrum
• Then click on the add button
• Change the load name as U2 (y - direction) function as IS function, keep the scale factor as it is
• Then click on OK

 

 

ETABS Output Values 

Check after analysis

Step49:- 

• In base reaction table the value of EQx value is almost similar to RSx 
• In base reaction table the value of EQy value is almost similar to RSy
• This similarity values is done by changing the scale factor of response spectrum

 

Step50:- 

• The principle mode should be greater than torsional mode
• In this table the principle mode is greater than torsional mode
• Mode 1 and 2 are greater than mode 3

 

Step51:- 

• It achieve 65% of modal mass participation for mode 1, mode2 and mode3

 

Step52:- 

• Here there is almost 50% difference for modal 1 to modal 2

 

Step50:- 

• The principle mode should be greater than torsional mode
• In this table the principle mode is greater than torsional mode
• Mode 1 and 2 are greater than mode 3

 

 

Step51:- 

• Maximum storey drift for Earthquake in x direction and for Earthquake in y direction
• This is for the Maximum storey drift for Earthquake in x direction
• The value is less than 0.004 (The value of exponential is in graph is 10^-6) so it is less than 0.004

 

Step52:- 

• Maximum storey drift for Earthquake in x direction and for Earthquake in y direction
• This is for the Maximum storey drift for Earthquake in y direction
• The value is less than 0.004 (The value of exponential is in graph is 10^-3)

 

Step53:- 

The formula for calculating axial force 0.4xfck

0.4 x 30 = 12

Then multiplied with 100 

12 x 100 = 1200KN

1200KN is the axial force

 

Step54:- 

Base shear shared between columns is 10%

Base shear shared between shear wall is 90%

My model is identified as a Shear wall system (It's not a Dual system)

Because, Base shear occured in the column is very negligible when compared to the shear wall 

 

 

 

Result:- 

Modal mass participation for first 3 modes dominates atleast 65% (Achieved for both x and y direction)

Mode 1 and mode 2 differs by 10% (Achieved)

Principle modes greater than torsional mode (Achieved)

Interstorey drift ratio limited to 0.004 (Achieved)

Axial stress in column and shear wall (Achieved)

Base shear share between shear wall and column (Not dual system)

Analysis for residential building appartment is succesfully done for the seismic load by using ETABS