Project 1_Comparative study of different storey buildings for Seismic forces

Aim - Comparative study of different storey buildings for seismic forces

Building A -

Procedure -

Step 1 -

• Open Etab software and select new model
• A new model dialogue box will open as model initialization

• Select Use in built in setting with option
• Select display unit as Metric,Steel design code,concrete design code,etc

• A new dialogue box will appear
• Select grid and story inputs and custom story data
• Enter X grid data at a distance of 4m and Y grid data at 4m distance
• Edit the stories by using the defined storey input,total stories is 2,plinth level at 1.5m and each story at 3m distance.and select one story as master story and other are similar to master storey.

• Select material properties under define tab
• Select concrete material M30 grade,longitudinal steel as 500 grade and transverse reinforcement as 415 grade

Step 2 -

• Under define tab select section property
• Click on frame section and create a new property as beam and input the values as 300X400mm

• After that,again select define tab and select the property for column as 400X400mm 

• After that,under define tab select slab property thickness as 150mm,shell thin type

Step 3 -

• Now draw column of size 400X400mm at the intersection of the grid using  quick draw tool keeping all stories ON
• After that,draw beams of size 300X400mm using quick draw beam keeping all stories ON
• Using quick draw floor tool,slab have been modelled keeping similar stories ON

Step 4- 

• Fix pinned support at the base

Step 5-

• To assign all loads
• Select define tab and then select load pattern
• Define the loads like dead load,live load,brick wall,earthquake load in X,+X,-X direction and also smae in Y,+Y,-Y direction and mention the IS code

• Click modify lateral load,set range from base to roof,seismic factor 0.36,time period 0.5,site type 3,eccentricty 0.05,Importance factor 1
• Do same procedure for all earthquake loads.

• Assign the load and select similar stories ON.click on Shell load under assign tab
• Click on live load as 3kn/m^2
• Click on Apply

• Roof will take 50% of live load i.e,1.5kn/m^2 keeping one story ON

• Similarly,add live load of 10 kn/m on all beams keeping all stories ON
• for that,select all the beams from select object type beam
• Then,select frame load and click on the distributed load and enter the value as 10kn/m

Step 6- 

• Load generation 
• Now go to mass source from define tab
• Modify the mass source and select the required load
• Add load pattern and assign the model

• Define load cases
• Select load combination  under define tab 
• Select frame design ON and convert to user combination

Step 7-

• Now create Diaphragms
• Under Assign tab select shell and click on Diaphragms keeping all stories ON

• Analyze the model using analyze option then click on check model,the modelled structure is verified without errors and warning

Step 8- 

• Run analysis
• Using analyze,the model is run and analyzed
• Go to show deformed shape or F6 tab will open and select the case as live and Ok

• Click on display menu select show tables,then the table will appear
• Select analysis result ,structure output,model information,model participation mass ratio

• A model participation mass ratio table will apppear with all the mass ratio acting on building

Building B -

Procedure -

Step 1 -

• Click edit tab and choose edit storey
• Add 5 storey and make 1st storey as master storey and all other as similar to 1st storey
• Click ok

Step 2-

• Click the select tab and select the column
• Click assign tab and choose frame assignment as 400x400mm column
• Click ok

Step 3-

• Now create Diaphragms
• Under Assign tab select shell and click on Diaphragms keeping all stories ON

Step 4 -

• Run analysis
• Using analyze,the model is run and analyzed
• Go to show deformed shape or F6 tab will open and select the case as live and Ok

• A model participation mass ratio table will apppear with all the mass ratio acting on building

• Fixed support

• Effect of flexural stiffness

Building C -

Procedure -

Step 1-

• Click edit tab and choose edit storey
• Add 5 storey and make 1st storey as master storey and all other as similar to 1st storey
• Click ok

Step 2-

• Click select tab and select the columns
• Click assign tab and choose frame assignment as 550x300mm coulmn 
• Click ok

Step 3 -

• Select the column object
• Click assign tab and choose frame section and then local axes
• Select rotation angle and enter 180 degree
• Click ok

Step 4-

• Now create Diaphragms
• Under Assign tab select shell and click on Diaphragms keeping all stories ON

• Analyze the model using analyze option then click on check model,the modelled structure is verified without errors and warning

Step 5-

• Run analysis
• Using analyze,the model is run and analyzed
• Go to show deformed shape or F6 tab will open and select the case as live and Ok

• A model participation mass ratio table will apppear with all the mass ratio acting on building

Building D -

Procedure -

Step 1-

• Click select tab and select the columns
• Click assign tab and choose frame assignment as 300x550mm coulmn 
• Click ok

Step 2-

• Select the column object
• Click assign tab and choose frame section and then local axes
• Select rotation angle and enter 180 degree
• Click ok

Step 3-

• Now create Diaphragms
• Under Assign tab select shell and click on Diaphragms keeping all stories ON

 Step 4-

• Run analysis
• Using analyze,the model is run and analyzed
• Go to show deformed shape or F6 tab will open and select the case as live and Ok

• A model participation mass ratio table will apppear with all the mass ratio acting on building

Building E-

Procedure -

Step 1-

• Click edit tab and choose edit story
• Add 10 story and make 1st story as master story and all other as similar to 1st story
• Click ok

• Elevation view of building 

Step 2-

• Run analysis
• Using analyze,the model is run and analyzed
• Go to show deformed shape or F6 tab will open and select the case as live and Ok

• A model participation mass ratio table will apppear with all the mass ratio acting on building

Building F -

Procedure -

Step 1-

• Click select tab and select the columns
• Click assign tab and choose frame assignment as 600x600 column
• Click ok

Step 2-

• Now create Diaphragms
• Under Assign tab select shell and click on Diaphragms keeping all stories ON

Step 3-

• Run analysis
• Using analyze,the model is run and analyzed
• Go to show deformed shape or F6 tab will open and select the case as live and Ok

• A model participation mass ratio table will apppear with all the mass ratio acting on building

Building G -

Procedure -

Step 1 -

• Click edit tab and choose edit story
• Add 25 story and make 1st story,11th story, and 21st story as master story 
• Click ok
• Click select tab and select the column of 21st  story  and assign them using frame assignment as 400x400

• Click select tab and select the column of 11th story 
• Click assign tab and choose frame assignment as 600x600 column
• Click ok

• Elevation view 

Step 2 -

• Now create Diaphragms
• Under Assign tab select shell and click on Diaphragms keeping all stories ON

Step 3 -

• Run analysis
• Using analyze,the model is run and analyzed
• Go to show deformed shape or F6 tab will open and select the case as live and Ok

• Deformed shape 

• A model participation mass ratio table will apppear with all the mass ratio acting on building

Building H -

Procedure -

Step 1-

• Click the define tab and click section properties
• Select add new property and choose column dimension 800x800
• Click assign tab and choose frame assignment as 800x800 column
• Click ok

Step 2-

• Select the column object
• Click assign tab and choose frame section and then local axes
• Select rotation angle and enter 180 degree
• Click ok

Step 3-

• Now create Diaphragms
• Under Assign tab select shell and click on Diaphragms keeping all stories ON

Step 4 -

• Run analysis
• Using analyze,the model is run and analyzed
• Go to show deformed shape or F6 tab will open and select the case as live and Ok

• A model participation mass ratio table will apppear with all the mass ratio acting on building

 

• Effect of axial stiffness

Building J -

procedure -

Step 1 -

• Click edit tab and choose edit story
• Add 25 story and make 1st story as master story and all are similar to 1st story
• Click ok
• Click select tab and select column
• Click assign tab and choose frame assignment as 800x800 column
• Click ok

Step 2 -

• Click  the select tab and assign the column as 800x800
• Click select tab and choose floor
• Click assign tab and choose shell loads then uniform load
• Make live load 10% large than building H
• Live load is 3kn/m^2 and 10% more means 3.3kn/m^2
• Click ok

• Roof load is 50% of all floor

Step 3 -

• Now create Diaphragms
• Under Assign tab select shell and click on Diaphragms keeping all stories ON

Step 4 -

• Run analysis
• Using analyze,the model is run and analyzed
• Go to show deformed shape or F6 tab will open and select the case as live and Ok

• A model participation mass ratio table will apppear with all the mass ratio acting on building

Building  k -

Procedure -

Step 1 -

• Click  the select tab and assign the column as 800x800
• Click select tab and choose floor
• Click assign tab and choose shell loads then uniform load
• Make live load 20% large than building H
• Live load is 3kn/m^2 and 20% more means 3.6kn/m^2
• Click ok

• Roof load is half of other story

Step 2 -

• Now create Diaphragms
• Under Assign tab select shell and click on Diaphragms keeping all stories ON

• Deformed shape -

Step 3 -

• Run analysis
• Using analyze,the model is run and analyzed
• Go to show deformed shape or F6 tab will open and select the case as live and Ok

• A model participation mass ratio table will apppear with all the mass ratio acting on building

Conclusion -

1) When comparing the building E,F and G,H,there is a significant difference of fundamental period.and the difference is due to different size of column.

The fundamental period of building E - 1.08 sec

The fundamental period of building F - 1.1 sec

The fundamental period of building G - 4.36 sec

The fundamental period of building H - 3.75 sec

2) Building H,J,K are of same story,but the load acting on building is increases gradually 10% on building J and 20% on building K.and due to this increase in load the building becomes more flexible.

The fundamental period of building H - 3.75 sec

The fundamental period of building J - 3.91 sec

The fundamental period of building K - 4.72 sec

3) The fundamental natural period of building A,B,F and H is varies gradually due to change in height of building 

The fundamental period of building A- 0.46 sec

The fundamental period of building B - 0.95 sec

The fundamental period of building F - 1.1 sec

The fundamental period of building H - 3.75 sec

4) When comparing the building B,C and D, The  fundamental natural period of each building is varies due to change of orientation of building.

The fundamental period of building B - 0.95 sec

The fundamental period of building C - 0.62 sec

The fundamental period of building D - 0.87 sec

5) The change of effect of flexural stiffness of structural element of building B is 0.95 sec

6) Effect of axial stiffness of vertical member of building H,the fundamental period is increased.it increases due to reduction of area.If the area is increased the capacity is increased.

The fundamental period of building H - 3.91 sec

7) The effect of degree of fixity at column bases is reduced in fixed support of building B

The fundamental period of building B - 0.85 sec