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Project 1_Comparative study of different storey buildings for Seismic forces

PPurnachander Rao Seelam27 Apr 2023

Aim:

To extract different seismic response of a structure and to alter certain properties using ETABS software.
To know factors influencing the dynamic characteristics of a building.
To know factors influencing the Natural Period of a building.
To know factors influencing the Mode shape of oscillations.

Introduction:

ETABS is an engineering software product that caters to multi-story building analysis and design.
ETABS stands for Extended Three-Dimensional Analysis of Building System.

Given data:

Procedure:

Open ETABS home page.
Go to file-> New model and give the following setting.
Click ok
For Building A:
Grid spacing and story data:
Give the following option for grid dimension and story dimension in new model quick template as shown below.
Click edit grid data
Click edit story data
Click ok
The following screen opens.
Defining Material properties:
For selecting material for rebars, Click Define-> Material properties-> Add new material
Click ok and select new material for concrete.
Defining Section property:
For beam
Click Define ->Section properties -> Frame section -> Add new property.
Select the shape as rectangle
Add beam size B300x400.
For reinforcement detail for beam, Click Modify/ Show rebars button to give following data.
Click ok.
For column:
Click add new property
Select the shape as rectangle
For reinforcement detail for column, Click Modify/ Show rebars button to give following data.
Click ok
For slab:
Go to Define -> Section property -> Slab section -> Add new property.
Click ok.
Defining load patterns:
Go to Define-> Load patterns
Enter additional loads and give above data and click add new load.
Click Modify Lateral Load for both seismic types respectively.
Click ok.
Defining mass source:
Go to Define -> Mass source -> Modify/ show mass source
Add mass multiplier for load pattern as above and click ok.
Check the load cases:
Go to Define -> Load cases.
Create load combination:
Go to Define -> Load combination ->Add default design combination.
Click ok
Combination has created.
Modeling:
To create Column:
Select Quick draw column icon in the panel and select the column property type as C400X400.
Select All story option in the bottom right.
Move the cursor on the grid and click to create column as shown below.
To create beam:
Select Quick draw beam icon in the panel and select the beam property type as B300X400.
Select All story option in the bottom right.
Move the cursor on the line in between the grids and click to create beam as shown below.
To create slab:
Select similar stories option in the bottom right.
Click plan icon on top of the panel and select the storey 1.
Select Quick draw floor icon and select slab property type as S150.
Click inside the frame.
The slabs are created in the similar stories.
To assign the loads:
Select set of particular elements and assign loads.
Beam:
Go to Select -> Select -> Property –> Frame section
Select the beam type.
Go to Assign-> Frame loads-> Distributed.
Give load pattern and load as mentioned above.
Slabs:
Select slab property as S150
Go to Select -> Select -> Property –> Slab section
Go to Assign-> Shell loads->Uniform.
Select the above load pattern and load and click ok.
Again, go to Select -> Select -> Property –> Slab section
Select Assign -> Shell -> Diaphragms -> D1.
Click ok.
Save the model:
To run the analysis:
Click Run analysis button on the top panel.
Deformed shaped of the building is provided
For Building B:
Save as:
Go to File -> Save as ‘Building B.P-1’
Adding stories:
To add extra stories, go to Edit -> Edit story and grid system -> Modify/ Show story data.
Place the cursor on the arrow cell and right click -> add story -> keep existing story heights, and then give the below option in the dialog box.
Change similar to option to story 1.
Click refresh view.
Loads:
Click Display shell load assign icon in the panel, Change the load pattern to live and click apply and ok.
Click Display frame load assigns icon in the panel, Change the load pattern to wall and click apply and ok.
Select the slab S150 and assign it as diaphragm as mentioned in earlier steps.
Analysis:
Click run analysis icon.
Building c:
Save as:
Click File -> Save as
Changing column property:
Go to Define -> Section property -> Frame section
Select the column and click Modify/ show property
Change the column size to 550X300.
Click ok
Changing Column orientation in X- direction:
Click Select -> Properties -> Frame section
And select the column which created now and click Select.
Click Assign -> Frame -> Local axes.
Give Orientational degree as 90.
Select the slab and assign it as diaphragm.
Analysis:
Click run analysis icon.
Building D:
Save as:
Click File -> Save as
Changing Column orientation in Y- direction:
Click Select -> Properties -> Frame section
And select the column which created now and click Select.
Click Assign -> Frame -> Local axes.
Change angle to 0.
Select the slab and assign it as diaphragm.
Analysis:
Click run analysis icon.
Building E:
Save as:
Click File -> Save as
Adding stories:
To add extra stories, go to Edit -> Edit story and grid system -> Modify/ Show story data.
Place the cursor on the arrow cell and right click -> add story -> keep existing story heights, and then give the below option in the dialog box.
Change similar to option as story 1.
Click refresh.
Check the loading as mentioned in the earlier steps.
Changing column size:
Click Define -> Section property -> Frame section
Click column and select Modify/ show property.
Click ok
Click Add New property to create another column type C400x400.
Changing top 5 floors column size:
Click Set display option, uncheck Beams and Floors option.

Click ok.
Only column is visible.
Go to View -> Set building view limits
Go to 3d view and select all columns.
Go to Assign -> Frame -> Section property
Top 5 floor columns are changed to C400X400.
Make Beams and floors visible again.
Select the slab and assign it to diaphragm.
Analysis:
Click run analysis icon.
Building F:
Save as:
Click File -> Save as
Changing column size:
Changing all column size to C600X600.
Click set display option and uncheck beams and floors
Go to view -> Set building view limits, have option as follow.
Click ok.
Go to Assign -> Frame -> Section property and select C600X600.
Change the view to Base to story 10.
Select the slab and assign it to diaphragms.
Analysis:
Click run analysis icon.
Building G:
Save as:
Click File -> Save as
To add extra stories, go to Edit -> Edit story and grid system -> Modify/ Show story data.
Place the cursor on the arrow cell and right click -> add story -> keep existing story heights, and then give the below option in the dialog box.
Change similar to option as story 1.
Click refresh view.
Creating new column size:
Go to Define -> Section properties -> Frame section.
Select C600X600 and click Modify/ Show property
Create a column size C800X800.
Select Add new property to create a new column size C600X600.
Assigning these column sizes to its respective floors:
Go to set display option and uncheck beams and floors.
Go to view -> set building view limits and give the settings
For top 5 Stories :.
Select as a whole and assign C400X400 to it.
For middle 10 stories:
Follow the above procedure.
Select as a whole and assign C600x600 to it.
For bottom 10 stories:
It is already assigned as C800X800 in the beginning.
Check the loads in all the stories and also ensuring the diaphragms properties.
Analysis:
Click run analysis icon.
Building H:
Save as:
Click File -> Save as
Changing column size:
Click Set display option icon and uncheck beams and slabs.
Select the column as a whole.
Click Assign -> Frame -> Section property
Click set display option and check beams and columns.
Analysis:
Click run analysis icon.
Building J:
Save as:
Click File -> Save as
To increase 10% mass:
Click Select -> Select -> Properties -> Slab section.
Select S150 and click select.
Click Assign -> Shell loads -> Uniform
Give load as 3.3 and select replace existing loads.
Click ok.
Analysis:
Click run analysis icon.
Building K:
Save as:
Click File -> Save as
To increase 20% mass:
Click Select -> Select -> Properties -> Slab section.
Select S150 and click select.
Click Assign -> Shell loads -> Uniform
Give load as 3.6 and select replace existing loads.
Click ok
Analysis:
Click run analysis icon.
Result:
The results have been taken from the Tables from respective building models.

Click Tables -> Analysis Results -> Structural output -> Model Information -> Model periods and Frequencies-> Show table
Click File -> Open, for respective building model.
Building E:
Building F:
Building G:
Building H:

Building J:
Building K:

Building A:
Building B:

Building c:
Building D:
Maximum storey displacement in X and Y direction:
Building B:
Building C:
Building D:

Save as:

Open the file B and save as follow.
Defining the beam:
Click Define -> Section properties -> Frame section.
Select the existing beam and click modify.
Change the below properties
Click ok.
Analysis:
Click Run analysis

Open the Building H.
Click File -> Save as
Click Define -> Section properties -> Frame section
Select C800x800
Give the above changes
Analysis:
Click Run analysis icon

Open Building B
Save as by below name.
Go to plan view select base
Select all the joints at the base
Click Assign -> Joints -> Restraints
Change it to fixed
Analysis:
Click run analysis

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