Modelling of 25 storey building with the specified properties using ETABS
Challenge 6 – ETABS modelling of a 25 storey building
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.
Carry out the following exercises:
- Check if the translational fundamental natural period of vibration in both the x and y direction is approximately: Tx1">Tx1= 4.4 second Ty1">Ty1= 4.2 second
This check will help confirm if modelling is done correctly. Some deviations from the above values is possible (± 2%). But any major deviation will suggest an error in modelling.
- Check if the following provision in Table 5 of IS 1893 (part 1) – 2016, on torsional irregularity satisfied:
The natural period corresponding to the torsional mode of oscillation must be less than the two fundamental translational modes of oscillation along each principal plan directions.
- Check if the two provisions of clause 7 in Table 6 (shown below) of IS 1893 (part 1) – 2016, regarding vertical irregularity is satisfied
- Check if provision on inter-storey drift limitations in clause 7.11.1.1 satisfied. Please note that this check is for Serviceability Limit State and hence is for situation when stucture is subjected to unfactored seismic base shear
STEP 1 : TO OPEN THE ETABS
Doble click on ETABS 2018 icon
Go file in manubar
Click on new model
Go to model initialization window
Select use built in settings with
Then select display units as metric SI
Steel section data base as Indian
Steel design code as IS 800 : 2007
Concrete design code as IS 456 : 2000
Finaly click on ok
STEP 2 : EDIT THE GRID DATA AND STORY DATA AS PER YOUR PLAN
Go to new model quick template
Go to grid dimensions (plan)
Select the uniform grid spacing
Give the no of grid lines in X direction - 5
No of grid lines in Y direction - 4
Spacing of grid in X direction - 4m
Spacing of grid in Y direction - 4m
Go to storey dimensions
Then select / click on custom storey data
Go to edit storey data
Edit the storey as your required
Change the storey name as your required
Change the height of storey also as your required
Change the similar to as plinth and storey 1 is none and remain floors as similar to storey 1
To add the remain floors
Mouse right click
Select add storey
Click on keep existing storey height
Give the storey height as 3m or based on your required
no of added storey as based on your plan
click on ok
then change the storey name as your required
Click on ok
Finally click on ok
STEP 3 : TO DEFINE THE MATERIAL PROPERTIES
CONCRETE MATERIAL AS M 30
Go to define in manubar
Then select material properties
Then open define material window
Go to add new material
Then select region as Indian
Material type as Concrete
Standard as India
Grade as M 30 or as your required
click on ok
Check the data
Click on ok
REBAR MATERIAL AS HYSD 415
Go to define in manubar
Then select material properties
Then open define material window
Go to add new material
Then select region as Indian
Material type as Rebar
Standard as India
Grade as HYSD 415 or as your required
click on ok
Check the data
Click on ok
STEP 4 : TO DEFINE THE SECTION PROPERTIES AS FRAME SECTIONS
COLUMN SIZE 800 X 800
Go to define in manubar
Then go to section properties
Then select the frame sections
Then open the frame section window
Go to add new properties
Then select the Concrete rectangular shape
Then give the property name as column 800 X 800
Material as M 30
Depth as 800 mm
Width as 800 mm
Then go to properties modify / show modifiers
Then change the moment of inertia about 2 axis - 0.7
moment of inertia about 3 axis - 0.7
NOTE : MOMENT OF INERTIA ABOUT THE AXIS IS 70% AS PER IS 1893 : 2016 (PART 1) CLAUSE NO 6.4.3.1
Then click on ok
Then go to Reinforcement
Then click on modify / show rebar
Design type as P - M2 - M3 Design (column)
Then go to rebar material
To change longitudinal bar as HYSD 415
Confinement bar as HYSD 415
Then go to Confinement bar size and area as 8mm
Finally click on ok
Click on ok
BEAM SIZE 300 X 400
Go to define in manubar
Then go to section properties
Then select the frame sections
Then open the frame section window
Go to add new properties
Then select the Concrete rectangular shape
Then give the property name as beam 300 X 400
Material as M 30
Depth as 400 mm
Width as 300 mm
Then go to properties modify / show modifiers
Then change the moment of inertia about 2 axis - 0.35
moment of inertia about 3 axis - 0.35
NOTE : MOMENT OF INERTIA ABOUT THE AXIS IS 35% AS PER IS 1893 : 2016 (PART 1) CLAUSE NO 6.4.3.1
Then click on ok
Then go to Reinforcement
Then click on modify / show rebar
Design type as M3 Design (beam)
Then go to rebar material
To change longitudinal bar as HYSD 415
Confinement bar as HYSD 415
Finally click on ok
Click on ok
STEP 5 : TO ASSIGN THE SECTION PROPERTIES AS FRAME SECTIONS
TO ASSIGN THE COLUMNS
Go to draw in manubar
Then go to draw beam / column / brace objects
Then select quick draw column
Then go properties of objects
Select the property as column 800 X 800
Then go to storeys options
Then select the all storey
Then assign or place the column on grid lines as your required
Then click on Esc
TO ASSIGN THE BEAMS
Go to draw in manubar
Then go to draw beam / column / brace objects
Then select quick draw beam / column
Then go properties of objects
Select the property as beam 300 X 400
Then go to storeys options
Then select the all storey
Then assign or place the beams on grid lines as your required
Then click on Esc
STEP 6 : TO DEFINE THE SECTION PROPERTIES AS A SLAB SECTIONS
SLAB THICKNESS 150mm
Go to define in manubar
Then go to section properties
Then select the slab section
Then go to slab properties window
Click on add new properties
Then open slab properties data window
Then give properties name as slab 150
Slab material as M 30
Modeling type as membrane
Thickness as 150mm
Click on ok
Finally click on ok
STEP 7 : TO ASSIGN THE SECTION PROPERTIES AS SLAB SECTIONS
Go to draw in manubar
Then go to draw floor / Wall objects
Then select quick draw floor / Wall
Go to properties of objects window
Select properties as slab 150
Then go storey options in down
Selecstorey as similar storey
Then assign or place the slab as your required plan
STEP 8 : TO ASSIGN SUPPORTS CONDITIONS
Go to view in manubar
Select the set plan view
Go to select plan view window
select base plan
Click on ok
Select the all column base points
Then go to assign in manubar
Go to joint
Select restraint
Go to joint assignments restraint window
select required pined support
click on apply
click on ok
STEP 9 : TO CHECK THE RENDER VIEW
Select the 3d view window
Go to view in manubar
Select show rendered view
Check the 3d view
STEP 10 : TO DEFINE LOAD PATTERNS
Go to define in manubar
Go to select load patterns
In default dead load and live load
Then add required Wall load and seismic load
WALL LOAD
Then give load as wall load
Type as super dead
Click on add new load
SEISMIC LOAD
Then give load as EQ X
Type as seismic
Auto lateral load as IS 1893 : 2016
Click on add new load
Then give load as EQ +X
Type as seismic
Auto lateral load as IS 1893 : 2016
Click on add new load
Then give load as EQ -X
Type as seismic
Auto lateral load as IS 1893 : 2016
Click on add new load
Then give load as EQ Y
Type as seismic
Auto lateral load as IS 1893 : 2016
Click on add new load
Then give load as EQ +Y
Type as seismic
Auto lateral load as IS 1893 : 2016
Click on add new load
Then give load as EQ -Y
Type as seismic
Auto lateral load as IS 1893 : 2016
Click on add new load
Then select EQ X load
Then click on modify lateral load
Then go to IS 1893 : 2016 seismic Loading window
Then select X dir only
Then deselect remain options
Then go to seismic zone factor Z
Select percode as 0.16 (zone III)
Site type as II
Important factor as 1.5
Response reduction as 5
Then go to time period
select user define T as 0.5 sec
Click on ok
Then select EQ +X load
Then click on modify lateral load
Then go to IS 1893 : 2016 seismic Loading window
Then select X dir + eecertricty only
Then deselect remain options
Then go to seismic zone factor Z
Select percode as 0.16 (zone III)
Site type as II
Important factor as 1.5
Response reduction as 5
Then go to time period
select user define T as 0.5 sec
Click on ok
Then select EQ -X load
Then click on modify lateral load
Then go to IS 1893 : 2016 seismic Loading window
Then select X dir - eecertricty only
Then deselect remain options
Then go to seismic zone factor Z
Select percode as 0.16 (zone III)
Site type as II
Important factor as 1.5
Response reduction as 5
Then go to time period
select user define T as 0.5 sec
Click on ok
Then select EQ Y load
Then click on modify lateral load
Then go to IS 1893 : 2016 seismic Loading window
Then select Y dir only
Then deselect remain options
Then go to seismic zone factor Z
Select percode as 0.16 (zone III)
Site type as II
Important factor as 1.5
Response reduction as 5
Then go to time period
select user define T as 0.5 sec
Click on ok
Then select EQ +Y load
Then click on modify lateral load
Then go to IS 1893 : 2016 seismic Loading window
Then select Y dir + eecertricty only
Then deselect remain options
Then go to seismic zone factor Z
Select percode as 0.16 (zone III)
Site type as II
Important factor as 1.5
Response reduction as 5
Then go to time period
select user define T as 0.5 sec
Click on ok
Then select EQ -Y load
Then click on modify lateral load
Then go to IS 1893 : 2016 seismic Loading window
Then select Y dir - eecertricty only
Then deselect remain options
Then go to seismic zone factor Z
Select percode as 0.16 (zone III)
Site type as II
Important factor as 1.5
Response reduction as 5
Then go to time period
select user define T as 0.5 sec
Click on ok
STEP 11 : TO ASSIGN THE LOAD PATTERNS
TO ASSIGN THE DEAD LOAD AS SLEFWEIGHT
Go to select in manubar
Then go to select options
Then select the object type
Select the beam
Click on select
Click on close
Go to assign in manubar
Then go to frame load
Then click on distributed
Then go to frame load assignments distributed window
Then select load pattern name as dead
Go to uniform load
Then give load as 1.5 KN/m
Click on apply
Click on ok
TO ASSIGN THE WALL LOAD
Go to select in manubar
Then go to select options
Then select / click on objects type
Select the beam
Click on select
Click on close
Go to assign in manubar
Then go to frame load
Then click on distributed
Then go to frame load assignments distributed window
load patterns name as wall load
Go to uniform load
Then give load as 10 KN/m
Click on apply
Click on ok
TO ASSIGN THE DEAD LOAD ON SLAB / FLOOR
Go to select in manubar
Then go to select options
Then select / click on objects type
Select the floor
Click on select
Click on close
Floor load as 3.75 KN/m^2 ( dead load )
Go to assign in manubar
Then go to shall load
Select uniform
Then go shall load assignments uniform window
Then select load patterns as dead load
Then go to uniform load
Then load as 3.75 KN/m^2 ( dead load )
Click on apply
Click on ok
TO ASSIGN THE LIVE LOAD ON SLAB / FLOOR
Go to select in manubar
Then go to select options
Then select / click on objects type
Then select the floor
Click on select
Click on close
FLOOR LOAD AS 3 KN/m^2 ( Live load )
Go to assign in manubar
Then go to shall load
Select the uniform
Then go to shall load assignments uniform window
Then select load patterns as live
Then go to uniform load
Then give load as 3 KN/m^2 ( Live load )
Click on apply
Click on ok
STEP 12 : TO DEFINE AND ASSIGN MASS SOURCES
Go to define in manubar
Then select mass source
Then go to mass source window
Then click on modify / show mass source
Go to mass source data window
Then give the mass source name mass source
Then go to mass source
Uncheck the elements selfmass and additional mass
Select the specified load patterns
Then go to mass multipliers for load patterns
Then select load patterns as dead load and multipler as 1
Click on add
Then select load patterns as wall load and multipler as 1
Click on add
Then select load patterns as live load and multipler as 0.25
Click on ok
Finally click on ok
STEP 13 : TO DEFINE AND ASSIGN THE MODEL CASES
Go to define in manubar bar
Select modal cases
Go to model cases window
Click on modify / show case
Go to loads applied
Then click on add
Load Type as acceleration
Load name as UX
Then click on add
Load Type as acceleration
Load name as UZ
Then click on add
Load Type as acceleration
Load name as UY
Then go to other parameters
Then maximum number of modes as 25
Minimum number of modes as 1
Then click on ok
Finally click on ok
STEP 14 : TO DEFINE AND ASSIGN THE LOAD COMBINATIONS
Go to define in manubar
Then select load combinations
Then go to load combinations window
Then click on add default design combinations
Go to add default design combinations window
Select the Concrete frame design
Click on ok
finally click on ok
STEP 15 : TO ASSIGN THE DIAPHRAGMS AS FLOORS
Go to select in manubar
Then go to select options
Then select objects type
Then go to select by objects type window
Select floors
Click on select
Click on close
Then go to assign in manubar
Then go to shall
Then click on diaphragms
Then go to shall assignments diaphragm window
select D1
Click on apply
Click on ok
STEP 16 : TO ANALYZE THE MODEL
TO CHECK MODEL
Go to analyze in manubar
Then click on check model
Then go to check model window
Select the select / deselect all
Click on ok
Then no warning's arise Then the model is ready
TO RUN ANALYSIS MODEL
Go to analyze in manubar
Then click on run analysis / press F5 function key
Our model as been analysised
STEP 17 : TO CHECK THE SUPPORT RECTIONS
Go to display in manubar
Then go to force / stress diagrams
Then select support / spring rection
Then go to reaction window
Then select the required load
Then select the required display results for these components
Then click on apply
Click on ok
STEP 18 : TO CHECK THE DEFLECTION
Go to display in manubar
Then go to deformed shape / F6 function key
Go to deformed shape window
Select required load / combo / mode options
Then click on apply
Then click on ok
STEP 19 : TO CHECK THE TABLES
Go to display in manubar
Click on show table
Go to choose table for display window
Go to structure output
Click on + symbol
Then select the required information
Then check the data
STEP 20 : TO CHECK THE STORY RESONSE PLOTS
Go to display in manubar
Click on storey response plots
Go to storey response plots window
Go to display type
Select the required plot
RESULT :
FROM THE TABLE THE TIME PERIODS , T X1 = 7.079 AND T Y1 = 6.825
THE 25 STORY BULIDING AS SUSFFULY ANALYZIED
THE TIME PERIOD SEPARATION OF LEAST 10% IS NOT ACHIEVED