Structural Modelling using Etabs 2018

Aim:

To model an apartment with all seismic consideration, based on given architectural input and to know how to check the seismic performance of an apartment using ETABS

Introduction:

To model and analyse the G+7 residential building with the given architectural drawing using ETABS

Objectives:

Data required for ETABS analysis-

• Pinned support, base + 9 story (ground to terrace) + 1 mumty
• Column 300x600mm & 300X750, beam 300x450mm, slab 150mm thick, shear wall 300mm thick
• Live load 2kN/m2, floor finish 1.5kN/m2, wall load 3.5kN/m, water tank 20KL over mumty equivalent to 200KN overall load

Conceptual design consideration before analysis-

• Re-entrant and cut-out check and modification (compromise)
• Vertical irregularity (soft story)
• Planar irregularity (looks symmetrical)
• 2% shear wall area with respect to build area (8m²)
• Stiffness modifier for column, beam & shear wall (0.35 for beam, 0.7 for vertical)

Key point to remember while modelling-

• No slab, no wall load in ground floor
• Proper end releases in beams as per engineer intent
• No interior wall load in terrace
• Comparison of static and dynamic forces and revising the factor

Procedure:

Step 1: First we have to create a model reference in AutoCAD.

• Open the given Dwg file in the AutoCAD.
• Now using this given DWG file, create a new one. In this you have to show the repositioning and resize of the columns and the orientation. Without disturbing the parking area.

• This drawing we have created is used as a reference drawing in the ETABS.

2. Now creating the grids as per the reference Drawing.

Step 1: Creating model in the ETABS

• Open the ETABS

• For creating a new model click on the New

Step 2: Creating the Model Initialization.

• Do the following setting given in the image below.

Step 3: Creating the Grids using reference drawing we have created in AutoCAD.

• After clicking on the OK in Model Initialization a new dialogue box will open.
• Select Custom Grid Spacing and click on the Edit Grid Data.
• Enter the X spacing of grids in (metre).
• Enter the Y spacing of grids in (metre).

3. Adding the Storey data

Step 1: Creating the storey data

• Click on custom storey data
• Edit the requires storey given in the challenge.

4. Defining the materials for the drawing.

Step 1: First define the materials properties.

• Click on the materials properties.

• Then a dialogue box will appear
• Click on add new
• Select Material Type Concrete and ensure Grade M30 click OK.

• Again, click on Add New Material
• Select Material Type Rebar and select Grade HYSD 550 & 415 click OK

5. Now we have to Add the Column, beam and shear wall.

Step 1: Adding the column

• In the Define tab, select Frame Section from Section Property.

• Click on Rectangular Section for Beam from Frame Property Shape Type.
• Change the Property Name as C300X600 and Material M30

• Now click on Modify show rebars option and change the settings.

Step 2: Adding the Beam.

• Click on Rectangular Section for Column from Frame Property Shape Type.
• Change the Property Name as B300X450 and Material M30

• Now click on Modify show rebars option and change the settings.

Step 3: Adding the Shear Walls.

• In the Define tab, select the wall sections.
• Then select the wall and provide the thickness as 300

6. Adding Load pattern.

• Click on Define
• Select the load pattern from it
• Now add different load case i.e. Live, Dead, Wall and Floor finishes as Super dead type and EQX and EQY as Siesmic type

7.Now defining Mass Source.

• Click on Define then select Mass source.

• A dialogue box will appear
• Now click on Modify
• Check mark only Specified Load Pattern
• Add wall, live and dead load,Floor finishes as shown below

8.Checking the Response Spectrum.

• Click on define
• Then Select the Response spectrum in the function

9. Checking the Load Cases.

• Click on define
• Then select the load cases.
• A dialogue box will appear which shows the Loads

10.Now for Load Combinations.

• Click on define
• Then Click on Load combinations
• Check the follwing things shown below.

11.Now Drawing the Columns, Beams and Shear walls.

Step 1: Drawing the Shear walls

• In the left side select the wall option
• And draw the shear walls.

Step 2: Drawing the beams

• Draw the beams as required

Step 3: Drawing the columns

• Select the columns from the property browser.
• And draw the columns.

12. Assigns the Load cases.

Step 1: Applying distributed load of 3kN

• Select all the beams
• Click on Assign and then click on the Frame loads and then distribution.
• Then modify the 3kN

Step 2: Applying the uniform load of 2kN

• Select all the beams
• Click on Assign and then click on the Shell loads and then Uniform
• Then modify the 2kN

13. Now Adding Diaphragms

• Select Slab
• Assign Shell as Diaphragms

14. Assigning the base support.

• Go to the base plan
• Select all the joitns
• Click on Assign then joints>restrian
• Select fast restrain and click ok
• All the joints are fixed

14. Run the Model Analysis

• After completion of anaysis we got max. & min. deflection

15. Check the result Result

• Form table checked the modal infromation and compare the result
• First two fundamental modal mass grater than the torsional mode
• Modal mass participation for first 3 modes dominates at least 65% (Achieved for X-axis only)
• Mode-1 and Mode-2 differs by 10% (Achieved)
• Principal modes be greater than Torsional mode (Achieved)
• Inter story drift ratio limited to 0.004 (Achieved)

Result:

To model and analyse the apartment with all seismic consideration, based on given architectural input and to check the seismic performance of an apartment using ETABS and attach the model