Modelling of 25 storey building with the specified properties using ETABS

AIM: To 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 1.5metres from the base. Each of the successive 25 Storeys has a Storey height of 3metres.

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: 10kN/m (Let us assume the same for roof floor in view of parapet)
• Live load on floor: 3kN/m^2 (Let us assume the same for roof floor)

1. a) Buildings are assumed to be pinned at the base
2. b) All columns in all Storey are of the same size
3. c) All beams in all Storeys are of the same size
4. d) Building is located on Soil type-II and in Zone-III. Assume other factors if required.

To carry out the following exercises:

• Check if the translational fundamental natural period of vibration in both the x and y direction is approximately: Tx1Tx1= 4.4 second Ty1Ty1= 4.2 second
• Check if the following provision in Table 5 of IS 1893 (part 1) – 2016, on torsional irregularity satisfied
• Check if the two provisions of clause 7 in Table 6 (shown below) of IS 1893 (part 1) – 2016, regarding vertical irregularity is satisfied

Introduction: -

• ETABS is an engineering software product that caters to multi-story building analysis and design.
• 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.
• Basic or advanced systems under static or dynamic conditions may be evaluated using ETABS
  ETABS modeling is the generalization that multi-story buildings typically consist of identical or similar floor plans that repeat in
  the vertical direction.
• Modeling features that streamline analytical-model generation, and simulate advanced seismic systems.
• Once modeling is complete, ETABS automatically generates and assigns code-based loading conditions for gravity, seismic,
  wind, and thermal forces.
• Users may specify an unlimited number of load cases and combinations.

Procedure:

STEP 1:

• Opening ETABS software.

• Click on new model option.
• A dialogue box will appear as model initialization.

• Choose the built-in settings option and select the display units and codes
• Metric SI<India<India
• After model initialization select the grid and story.
• 
• In this dialogue box choose custom grid spacing and custom story data.
• Enter X grid data at a distance of 4 (Total 16 m) meter and Y grid data at a distance of 4 m (Total 12 m)

• Edit the stories by using the user defined Storey input,26 Storeys are incorporated (plinth at 1.5-meter height+ 25 Storey with 3-meter height each). Storey 1 has been labelled as master Storey and all above levels are labelled similar.
• 

STEP 2:

Define Materials

• Select material properties under the define tab.
• Define the materials of concrete M30 grade.
• 
• 

• Define Rebar as Fe415.
• 

STEP 3:

Define Section Properties

• Go to define tab and select selection properties.
• Click on the frame section and create a new property as concrete rectangular.
• After that give input Property name as B 400x300 and give material as M30 and dimension as 400 in depth and 300width.
• Same as for Column (C 800 x 800)
• 

STEP 3:

• Define Slab from Section properties.
• Property name Slab150 < Slab material M30 < Thickness 150mm.

STEP 4

Define Load:

• Go to Define Tab and select load pattern.

• Modifying lateral load

• Now go to again Define Tab and Select Load Combination < Add Default design Combo < Concrete Frame Design

STEP 5:

Draw Properties

• Select Stories All
• Select Quick Draw Column Tool
• Now draw a column of size 800X800mm at the intersection of the horizontal and vertical grid and beams.

STEP 6:

• Beams drawn using quick draw beam tool at all the stories.

STEP 7:

• Select Story 1 and click to similar story.
• Using the quick draw floors option Draw the Floor.

STEP 8:

• Assigning joints
• Select Base of the building and select One story
• Select all the column
• Go to assign Tab < Joints < Restraint < Pinned joint

STEP 9:

Applying Load

• Assign the loads and select similar stories.
• 
• Loads on Floors
• Click on shell load under the assign tab
• Click on live load and give value as 3kn/m^2.
• Click on apply.

• For roof we will take only 50% of the live load.

STEP 10:

Loads on Frames

• Similarly add live load of 10Kn/m^2 on all the beams at similar story.
• For that select all the beams from select object type beams.
• Go to the frame load and click on the distributed load and enter the value as 10Kn/m^2.

STEP 11:

• Now go to mass source from the define tab.
• Modify the mass source.
• Add load patterns and assign to the model.
• Dead =1 < Live load=0.25 < Wall=1

STEP 12:

Diaphragm for the Building

• Now create the diaphragm by going to the assign tab then shell and select diaphragms.

• Click on ok.

STEP 13:

Analyzing the Model

• Before Analyzing model, we have to check any errors from Analyze tool.
• No errors

Now Analyze the Model.

Analyzing Successful.

Checking the Tables and Deforms Shapes of the Model.

STEP 14:

• Next, from the display option we select the show tables option, as shown below.

• After selecting the show tables option the new tab will be visible.
• Now we select the Modal Participating Mass Ratios and click on the ok button, as shown below.

• Next the Modal Participating Mass Ratios table will be visible, as shown below.

RESULT: -
The 25 Storey building has been modelled successfully in the ETABS