Structural Modelling using Etabs 2018

AIM:Structural Modelling using Etabs 2018

Introduction:

The architectural drawings for a G+7 residential building in zone 5 has been provided. The floor plan is the same for all 7 floor levels. Possible column positions have also been provided. Conceptualize a framing plan layout and then model the building in Etabs. The following architectural drawings have been provided:

• Typical floor plan – The location and thickness of the brick walls and the use of the
  space (for estimating live load) can be obtained from this plan
• A building section through the staircase and lift core is provided
• Parking layout in the ground floor – the column/shear wall arrangement must not
  obstruct entry/exit of vehicles.
  The following loadings are to be taken into account:
• Brickwall made of AAC blocks
• Finishes – floor tiles of 75 mm thickness
• Live loads as per IS 875 part 2
• Water tank of 20 KL above the staircase at Mumty level
• Lift Machine room at mumty level above lift core

Procedure:

The Above mentioned Project is done as per Is 1893 Part-1 2016 the following procedure is as follows,

Step-1

• Open E-tab Software and Select a new file and save the project as Challange 6

Step-2

• Now the is step is to set the Model initialization.
• Select the built in option.
• In which select unit as metric SI.
• Steel section database as Indian.
• Steel Design code as IS 800 2007.
• Concrete Design code as Is 456 2000 and press ok as shown below.

Step-3

• Now Giving the Spacings of Grids.
• Select grid only option and press ok.
• Now select display grid data as spacing.
• and provide spacing of 6.4m in x direction and 6.4m in y direction.
• 5 grids along x and 4 grids along y as mensioned in question.
• As shown below.

Step-4

• Select the Storey Data and input the data as mensioned.
• That is select 9 story that is Plinth level and 8 Floors and Roof.
• With 1st floor as master storey and remaining 8 floors as its copy as shown below.
• After completely renaming the Storey press ok.

• Now the model will appear as shown below.

Step-4

• Now its time to define the materials Properties
• Select concrete as Indian and M30 grade.
• For steel select Rebars Indian ie HYSD 415 grade.
• After completing Selct ok as shown Below.

Step-5

• Now give Section Properties for Column, Beam and Slab ie.,
• For Column select size as 400x400mm
• For Beam 300x550mm
• And For Slab 115mm thk.
• 

Step-6

• Now placing of Columns and Beams is done.
• select the quick column option and select Column C1 i.e., 400x400 and place it where required.
• Simillarly select quick beam and select the grids where beams are required.
• and also select quick slab selection and place the slab of given size i.e., 115mm thk.
• And Must be noted that the all storeys option should be selected.

• This is how it will appear after assigning the materials to the grids.

Step-7

• Now its time to assign the Supports whether fixed or hinge or pined
• In this case hinge support is given that is restricted along x and y only.
• it is done by selecting the points from base plan and assigning the hinge support as shown below.

Step-8

• Defining of loads acting on the building that is
• Dead load, live Load, Wall Load, and Earthquake load.
• For Earthquake load There loads are given those are EQ in X, EQ in X+, EQ in X- and EQ in Y, EQ in Y+ and EQ in Y-
• As shown below.

Step-9

• Now Its time to assign the loads where ever acting
• Select the shell load option and assign the shell load of 3kN/m2 ton each slabs.
• and by selecting distributed load option and giving 10kN/m to all the beams placing between the column as shown below.

• To Check whwther the loads are propery placed use Perspective Toggle option.

Step-10

• Now its time to assign the load combinations
• As in etabs Load combination is alreay defined just to select proper load combination
• and press okay to assing as shown below

Step-11

• Now Assign the Diaphagram in the sloabs.
• as it is important to set the center gravity of structure as shown below

Step-12

• Now Assign the mass sorce data and modal case data
• so that select the assign option and select modal sorce data
• and along with that select modal case data and assign to the structure.
• As shown below.,

Step-12

• Now the last step is to annalyze whether the structure is free from errors or not
• So select the analyze option and check all the options as shown
• and wait for the message to display as shown below,

RESULT:

The structural model must comply with provisions of IS 1893 and IS 13920.
Run a modal response spectrum analysis and check analysis results of the etabs model for inter-storey drift requirements, vertical & planar irregularities, minimum shear wall requirements,maximum axial load ratio for column and shear walls, effective moment of inertia for beams

• In the x dirction as per graph the value lies between 4 hence it is acceptable in x direction,

• In the Y dirction as per graph the value lies between 4.5 hence it is not acceptable in y direction,

From the above figure it is observed that the building is symmetrical as the area of walls in x direction and y direction is almost simillar.

Effective moment of inertia for beams