Challenge

Project 1_Comparative study of different storey buildings for Seismic forces

HHimali Ramteke24 Aug 2022

AIM :
TO MODEL AND ANALYZE MULTIPLE BUILDINGS WITH DIFFERENT FLOOR LEVELS AND DESIGN PARAMETERS USING ETABS SOFTWARE AND COMPARE THE RESULTS TO UNDERSTAND THEIR OVERALL SEISMIC BEHAVIOUR.

INTRODUCTION :
1) ETABS is an engineering software product that caters to multi-story building analysis and design.

2) 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.

3) Basic or advanced systems under static or dynamic conditions may be evaluated using ETABS.

4) For a sophisticated assessment of seismic performance, modal and direct-integration time-history analyses

may couple with P-Delta and Large Displacement effects.

5) Different building geometries behave differently when induced by the same seismic forces.

6) Hence, it is very important to properly understand the response of buildings related to their structural

configurations for a safer design approach.

7) Therefore in this project, we have modeled different buildings with varying geometries using ETABS.

8) Furthermore, their responses are analyzed with the help of the software and the results

are then compared to grasp an understanding of the structural behavior of buildings with different storeys.

BUILDING A

STRUCTURAL ELEMENT :
Beams - 300x400 mm
Columns - 400x400 mm
Slab - 150 mm

MATERIAL USED :
Grade of concrete - M30
Grade of steel Reinforcement Bars - Fe 415
Dead Load on beams from infill wall - 10kN/m
Live load on floor - 3kN/m2 (Assume this live load for same roof floor also)

BUILDING A
PROCEDURE :
STEP 1
start the etabs software
then home page of etabs software is open
from that click on NEW MODEL
Once you click on New model
A Model Initialization setting will open
From that Select Metric SI unit
From that Select Metric SI units
Then Select section database Indian
Select Steel code IS 800-2007
Select Concrete design code IS 456-2000
click ok
STEP 2
After clicking the ok
then one new dialogbox is open as shown below
from that click on custom grid spacing tab
then again new tab is open as shown below
click on Display Grid Data As Ordinates
then ADD more one grid
as shown below
click on ok
Again New Model Quick Templet is shown
from story dimension column
click on Costom Story Data
then Click Edit Story Data
new tab is open
from that give plinth heignt is 1.5 m
and other two story is 3 m
click ok
STEP 3
After clicking ok then plan view and 3d view of the structure is shown in workspace
STEP 4
Now we have to define the materia properties
Click on Define

Click on Material properties
so that go to define tab
click on material properties
so that go to define tab
click on material properties
click on Add New Material
set standard as Indian
set grade as M30
Click OK
click OK
Then Add another material
select standard as Indian
Grade as HYSD Grade 415
click OK
Click OK
Both steel and concrete material is added
click ok
STEP : 5
Define slab section
so that go to the define tab
click on Section properties
then click on slab section
then one dialogbox is open
click on Add New Properties
then give the properties name as Slab150
give the slab material as M30
and thickness of slab as 159 shown below
click OK
STEP : 6
Difine a load pattern
so that click on Define tab
click on load pattern
then give the load shown beow
click on EQX load
then click on Modify Lateral Load
then new dilogbox is open shown below
click OK
again click on EQY
then Modify Lateral Load
click OK
STEP : 7
Define Mass Source
so that go to the define tab
click on mass source
then new dialogbox is open
from that click on
Add New Mass Source
Add Dead load ,Live load ,Wall load shown below
click OK
Then click OK
STEP 8
Check load cases
so that click on Define tab
click on load cases
click ok
Load combination
for that again go to define tab
click on Load Combination
one dialogbox is open
click on Add Defoult Design Combination
select Concrete Frame Design Option
click ok
click ok
STEP 9
Asign columns for the structure
for that go to Quick Draw Column option
then Properties Object Dialogbox Is open
from that click on Properties Of Object
select the C400x400 as shown below
Then draw the columns as shown below
STEP 10
Asign Beams For the structure
for that go to the Quick Draw Beam Option
then Properties Of The Object Dialogbox is open
from that click on Properties of Object
select beam as B300x400
Then draw the beams as shown below
STEP 10
Asign slab fot the structure
select the similer story option because we dont want slab at plinth level
click on Set plan View
select Story 1
Click on APPLY and OK
Then go to the Quick Draw Slab Option
properties dialogbox is open
from that select S150
and draw the slab as per shown below
STEP 11
Asign Loads for the structure
so that Go To The Select Option
Click on Properties
select the Frame section
Select the Beam Properties shown below
then close it .
Then go to assign tab
click on Frame Loads
then click on Distrubited
then one dialogbox is open
fromthat select the load pattern as wall
and give the wall load as 10 kN .
click on APPLY and OK
STEP 12
appy 3 kN live load on slab
so that Click ON Select Option
then properties
slab section
select it and then close it
Then go to the Assign tab
click on Shell Load
Then Uniform
one dialogbox is open as shown below
form that select the load pattern as Live load
give the load as 3 KN
click on APPLY and then OK
STEP 13
Asign diaphragms
to calculate center of mass and rigidity of the structure is calculated .
so that select the all slab
go to the select tab
click on properties
then slab section
select the slab
and then close
then go to Assign tab
Click on Shell option
then Click on Diaphragms
select D1 option
click on Apply and Then Ok
STEP 14
RUN ANALYSIS

BUILDING B (G +5 )
Now to model building B, we need not create a new ETABS file from scratch.
Rather we will save a copy of the building A file and do the alterations needed for building B.
we can increase the number of stories to 5 by editing the story data within the copied file. So, the complete procedure to do so in ETABS is discussed below:
Click on save
STEP 2
Insrease the story of the buildig
so that ,
Click on Edit
edit story on grid
one dialogbox is open
from this dialogbox click on
click on Modify/ Show story data
one new dialogbox is open
click on add story
add 3 more story
click OK
Click ok
Click ok
STEP 3
Checked whether load is applyed or not
so that click on Display Shell Load Assign
one dialogbox is open
seect the load pattern as live load
click on apply and then ok
Then checked the wall load
so that click on
Display Frame Load Assign tab
select the load pattern as wall load
click on Apply and then OK
STEP 4
Assign Diaphragms
so that first select the slab section
click on Select tab
then properties and then slab section
one dialogbox is open
click on Select
and then close
then click on Assign tab
then click on Shell and then diaphragms
one dialogbox is open
then click on D1
Then click on APPLY And then ok
STEP 5
Run Analysis

BUILDING C
The story and grid data for building c will remain still.
we need to change the column size and orient the same in the X-direction.

PROCEDURE :
STEP : 1
Change the column size of the building
so that , go to Define tab
Then Section Properties , Then Frame Section
one dialogbox is open
click on c400x400
then click on Modify/Show Properties
new dialogbox is open
From that give the name as C550x300
depth of column is 550
and width of column is 300
then click ok
again one dialogbox is open
from that click ok
STEP 2
select the columns
for that go to Select tab
then Properties , then frame section
one new dialogbox is open
click on Select option and then closed .
STEP 3
Rotate the columns at 90 degree
so that , Go to the assign tab
then click on Frame and Then Local Axis
one dialogbox is open
from that give the angle as 90 degree
click on Apply and Then OK
STEP 4
Selcect the slab
go to the Select tab
then Properties Then Slab section
click on Slab150 and then click ok
STEP 5
Select the diaphragms
go to Assign tab
click on shell and then diaphragms
click on Apply and then OK
STEP 6
Run Analysis
Click on Run Analysis tab
it takes some time to loft

RESULTS :

BUILDING D
In this model, we don't need to change anything other than the column orientation.
The sizes of the column will remain the same .
we have to shift the column orientation from X to Y direction.
PROCEDURE
Click on File tab
Then click on Save As
Give the name of the file as Building D
and then save it
STEP 1
Change the column to Y axis
so that , first select the column
click on Selct tab
then click on Properties
and Frame Section
then click on c550x300
select it and then close it .
STEP 2
Change the direction x to Y
so that click on Assign tab
click on Frame
then click on Local axis
one dialogbox is open
from that change the angle 90 degree to 0 degree
click on APPLY and then ok
STEP 3
for that select the slab first
click on Select tab
then properties
then Slab section
select the S150 and then close it.
STEP 4
Check for diaphragms
click on Assign tab
then shell option
then click on diaphragms
click on Apply and then OK
STEP 5
Run analysis
RESULTS :

BUILDING E (G+ 10 )
Column sizes :
for top 5 storeys: C 400X400
Column sizes
for bottom 5 storeys: C600X600

PROCEDURE :
In this model, we need to add up 5 more storeys to our model.
In addition, we also need to assign different column sizes on different floors.
we'll first save the ETABS file for building D as a new model for building E.
Then, edit the story data as we have done for our previous models in ETABS.
Then, we need to add two new column sections with the required directions and assign them at appropriate floors in our model as specified.
STEP 1
Add 5 more story in previous structure
so that go to the Edit option
click on Edit Story And Grid System
one dialogbox is open
from that click on Modify Story Data option
add 5 story there shown below
refresh it and then click OK
click ok
STEP 2
Check the wall load and floor load of the structure
click on Display shell load assign
select the load pattern as live load
click on APPLY and ok
again click on Display Frame Load Assign
select the load pattern as wall load
Click on Apply and then OK .

STEP 3
Change the column size as 600x600
so that click on Define tab
then Section properties
then Frame section
select the c550x300
then click on Modify section
one dialogbox is open shown below
give the property name as c600x600
give the depth as 600
and width as 600
click OK .
Then Add one more new column size 400 by 400
so that click on Add new proprties
give the name as c400x400
then width of column as 400
depth as 400
Click OK
STEP 4
Select the column only
for that hide the beam and floor
click on set view point tab
and unselect the beam and floor and then click ok
click ok
STEP 5
Select the column from floor 6 to 10
so that , click on view tab
Then click on Set Building view Limits
one dialogbox is open
from that select the Top story as Story 10
and base story as story 6
then click ok .
3D VIEW :
Select the all columns
then click on Assign tab
then click on Frame and then click on Section Properties
one dialogbox is open
select the c400x400 and then click on APPY and then ok
3D VIEW

STEP 5
Then checked for diaphragms
so that select the slab first
go to the select option
then click on properties and slab section
one dialogbox is open
click on seect and then close it .
then click on Assign tab
then click on shell
and then diaphragms
one dialogbox is open
click on Appy and then OK

STEP : 6
RAN ANALYSIS
RESULTS :

BUILDING F (G+10)
Throughout the structure having same columns size
no need to much editng in the previous structure
jast change the column size from story 6 to 10 as 600x600
PROCEDURE :
STEP 1
Hides the beams and floor
so that click on Set Display Option
and just unselect the Beams and floor
click on Apply and then OK
3D VIEW :
STEP 2
Select the columns from story 6 to 10
so that click on View tab
Set Building LImets
then one dialogbox is open
from that click on
tao story as 10 story and
base story as 6 story
click on OK
STEP 3
Change the columns size as 600x600
so that jast select the columns
click on Assign tab
then click on Frame and then Section Properties
then one dialogbox is open
from that click on c600x600 columns
click on APPLY AND THEN OK .
Then click on view tab
then click on Set Building View Limets
one dialogbox is open
from that select the top story as 10 story
and bottom as base
click ok .
3d view :
STEP 4
Again select the beams ad floors
click on Set Display Option
open dialogbox is open
from that click on Beam and slab
and then click ok
3d VIEW :
STEP 5
Check for diaphergram
so first select the slab
click on Select the tab
and click on Properties
then Slab section
one dialogbox is open
select the slab150
and then closed it .
Then click on Assign tab
click on Shell and the diaphergrm
one dialogbox is open
click on D1
Then click on APPLY and then OK .

STEP 6
RUN ANALYSIS :

RESULTS :

BUILDING G (G+25)
Columns for top 5 stories: C400X400
Columns for middle 10 stories: C600x600
Columns for bottom 10 stories: C800x800

PROCEDURE :
we need to add 15 new stories and assign different column sizes on different floors.
We can follow the exact procedure that has already been explained for the previous project to create this model by editing building F. The same
STEP 1
Click on File manu
then click on Save As then give the fine name as BUILDING G
STEP 2
Add more 15 story in previous story
so that click on Edit
then click on Edit Story And Grid System Data option
one dialogbox is open
from this click on Modify /Show Story data
again one dialogbox is open
from that add more 15 story
click ok
click ok
click ok .
STEP 3
check the live load and wall loads of the structure
Check Live load :
click on Display Shell Load Assign
one dialogbox is open
select the load pattern as Live load
click on Apply and then OK .
Check wall load
so that click on Display Frame Load Assign tab
one dialogbox is open
select the load pattern as wall load
click on Appy and then OK

STEP 4
define columns
c400x400
c600600
c800x800 .
so that click on Define tab
then Frame section
one dialogbox is open
create a new column
c800x800
click on OK .
STEP 5
Apply different size of columns for each story
so that click first hide the beams and floors of the structure .
click on Set Display View tab
unselect the beam and floors option
click on Apply and then OK .

STEP 6
Click on assign tab
then click on Frame and then Section Properties
one dialogbox is open
select the c400x400
click on Appy and then OK .
3D VIEW :
Middle 10 story provided with column size as 600x600
again click on View option
then click on Set Building Limets option
one dialogbox is open
select the top story as story 20
and bottom story as story 11
click on OK .
then click on Assign tab
then click on Frame and then Section Properties
one dialogbox is open as shown below

again click on View Option
click on set building view limets
then Make visible beam and slab of the structure
click on Set Display Views Option
and select the Beam and Slab Option
and then click on OK.
STEP 7
CHECK for diaphragms
first select the slab
click on Select tab
then again click on Select and then properties , next is slab section
one dialogbox is open
from that click on Slab150
click on Select and then closed it
click on Assign tab
the click on Shell and then Diaphragms
one new dialogbox is open
from that select D1
click on APPLY and the OK

STEP 8
RUN ANALYSIS

RESULTS :

BUILDING H (G-25)
All column size is 800x800
PROCEDURE :
First click on File option
then click on Save as
Give the file name as BUILDING H
and the save it
STEP 2
First hide the Beam and floor
and the click on APPLY and the OK
STEP 3
Assign all columns as 800x800
so that first select the columns
then click on Assign tab
then click on Frame and then section properties
one dialogbox is open
From that click on c800x800
click on APPLY and Then OK .
STEP 4
Select the beam and slab
so that click on set display option
then select the beam , floor and diaphragms option
click on APPLY and then OK .

STEP 5
RUN ANALYSIS :
RESULTS :

BUILDING J (G+25)
IN THIS CASE INCREATSE THE 10 % IMPOSED LOAD MEANS LIVE LOAD
PROCEDURE :
STEP 1
Select the all the slab
click on Select tab
then click on select tab then section properties and slab section
one new dialogbox is open
from that click on Slab150
then click on Select and then closed
STEP 2
Increase the 10 % of live load
so that click on Assign tab
then shell load
then click on Unifom
one dialogbox is open
give the load as 3.3
then click on APPLY and then ok
STEP 3
RUN ANALYSIS :
RESULTS :

BUILDING K (G+25)
In this case the increase the mass of the building by 20 persent imposed load means live load .
PROCEDURE :
STEP 1
Click on File tab
then click on Save as give the file name as BUILDING K
And then save it .
STEP 2
Increase the live load by 20 persent
click on Select tab
then again click on Select and then properties and
then slab section .
one dialogbox is open
select the Slab150
select it and then closed it .
STEP 3
Assign load
so that click on Assign tab
then click on Shell load
then click on Uniform
one new dialogbox is open
from that select the load pattern as live load
then give the load 3.6
click on APPY and then ok
STEP 4
RUN ANALYSIS :
RESULTS :

RESULTS :

Results-All the 10 buildings were modelled and analysed successfully.

A] Effect of stiffness on T: Compare fundamental nature periods of building E&F as well as G & H.

Why id there a marginal or significant difference in the fundamental natural periods?

Model Type	No of Stories	Column configuration	Results	Conclusion
Building E	10	Upper 5 stories = 400x400 mm Bottom 5 Stories = 600x600 mm		As we could see that by changing the column sizes there will not be any effect on Natural period, it remains Same
Building F	10	Column Size = 600x600mm Uniform throught Building		As we could see that in Building H has uniform column section but it has more natural time period
Building G	25	Column Sizes Bottom 10 story (800x800 mm) Upper 10 story (600x600 mm) Top upper 5 story (400x400 mm)		Where as building G has large column at its base and reduces as we go higher level. But it has less natural time period as compared to H = ___
Building H	25	Column size = 800x800 mm Uniform throught Building		So we can conclude that providing larger size of column at base and reducing the size at higher level will reduces the Natural time period

B] Effect of mass on T: Compare fundamental natural periods of buildings H,J and K. Have the buildings become more flexible or stiff due to change in mass

Model Type	No of stories	Percentage increase in Load (Mass)	Result	Conclusion
Building H	25	Load is taken as 3KN/m2		As we could see that time period is increase as we increase the load or mass
Building J	25	Load Increase by 10% (3.3kn/m2)		Therefore time period is directly proportional to the mass of the building
Building K	25	Load Increase by 20% (3.6kn/m2)

C] Effect of building Height on T: How does the fundamental natural periods of Buildings A,B,F and H change with change in building height?

Model Type	No of stories	Height of Building	Results	Conclusion
Building	2	7.5 m		As we could see that the height of the building increases the natural time period is also increases Therefore, the natural period 'T' is also directly proportional to the building height
Building B	5	16.5 m
Building F	10	31.5 m
Building H	25	46.5 m

D] Effect of column orientation on T: How does the fundamental natural periods of building B, C and D change with change in column orientation?

Model Type	No of dtories	Column orientation	Results	Conclusion
Building B	5	Equal in Both Direction 400x400 mm		As we could see that when column is orientad in X and Y direction in Time period
Building C	5	In X direction 550x300 mm		So we can say that in Y direction Lateral Displacement is more as compared to X direction
Building D	5	In Y direction 300x550 mm

E] Effect of flexural stiffness of structural elements on mode shapes: Compare fundamental mode

shape of building B in two situations when the flexural stiffness of beams relative to that of adjoining columns is very small versus it is large

Model Type	No of stories	Flexural stiffness of beam	Results	Conclusion
Building B	5	100%		If you decrease the flexural stiffness of beams,the overall flexural strenght of the beam is also going to reduce which increase the Natural period of time
Building B	5	10%

F] Effect of Axial Stiffness of vertical Members on mode shapes: Compare the fundamental mode shape of building H in two situations when the axial cross-sectional area of columns is very small versus when it is large.

Model Type	No of stories	Axial Stiffness of Columns	Results	Conclusion
Building H	25	100%		As we axial stiffness of columns decrease, the fundamental natural period of the building increases regardless of its structural geometry
Building H	25	10%

G] Effect of degree of fixity at column bases on mode shape: Compare the fundamental mode shape of Building B in two dituations when the base of columns is pinned versus when it is fixed.

Model Type

No of stories

Base support

Result

Conclusion

Building B

Pinned

As we can see that in pinned support natural time period is more as compared to fixed support.

Therefore fixed support will provide more resistance as compared to pinned support

Fixed

BUILDING A

BUILDING B

BUILDING C

BUILDING D

BUILDING E

BUILDING F

BUILDING G

BUILDING H

BUILDING J

BUILDING K

Project 1_Comparative study of different storey buildings for Seismic forces

Ship work like this
in your own course.

Talk to a career counsellor

Ship work like thisin your own course.

Talk to a career counsellor

Ship work like this
in your own course.