Structural Modelling using Etabs 2018

CHALLENGE 10:

Structural Modelling using Etabs 2023

AIM:

Structural Modelling using Etabs 2023

INTRODUCTION:

The following figure illustrates the use of ETABS to model the structural behavior of a simple building.

The following steps are used to model the building in ETABS:

1. Draw the outline of the building on the screen.

2. Assign material properties to the walls, roof, and floor slabs.

3. Define the geometry of the walls, roof, and floor slabs.

4. Define the loads that will be applied to the building.

5. Solve the structural equations to determine the structural response of the building.

QUESTION:

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

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
and columns etc.

Please note that the column positions shown in the architectural typical floor plan are only to provide an initial starting point for modelling. Participants will have to change its size, introduce shear walls, and add new vertical elements after running the analysis. You will have to run the analysis multiple times until a structural model is obtained that meets structural code requirements without compromising architectural functions. Also, there is no one ‘correct’ structural system for this challenge. There can be multiple possible solutions for this problem.

PROCEDURE:

Data required for ETABS analysis:

• Pinned Support, Base + 9 Story (Ground to terrace) + 1 Mumty
• Column 450mm x 600mm, Beam 400mm x 500mm, Slab 150mm thick, Shear wall 300mm thick
• Live load 2.5 kN/m2, Floor finish 1.5 kN/m2, Wall load 5 kN/m, Water tank 20K litre over mumty equivalent to 200 KN overall load.

Conceptual design considerations before analysis:

• Re-entrant and cutout check & modification (Compromise)
• Vertical irregularity (soft story)
• Planar irregularity (Looks symmetrical)
• 2% shear wall area with respect to building area (8 m2)
• Stiffness modifier for Column, Beam & Shear wall (0.35 for beam, 0.7 for vertical)

1. Open the New ETABS software 2023.

2. Now Set the limits like grids and storeys according to the required architectural drawings.

3. Now Define the material properties like concrete and rebars. Go to the Define option to select the Material properties and enter the material.

4. Now Define the section properties like Beams, Columns, Slab and walls.

BEAMS:

COLUMNS:

SLABS:

Walls:

5. Now Create the Geometric modeling of all section elements.

Columns:

Beams:

6. Now Adjusted to all Beam sections required for drawings and draw the shear walls wherever required.

7. Now Draw all floors required for Architectural drawings.

8. Now Define the load patterns for all framed sections.

9. Live loads are calculated by using IS 875 part 2.

10. Now I need to apply earthquake loads to the modelling.

11. Now apply the Pier labels to the Shear walls other wise not design the modelling.

12. Now add load combinations to the entire modelling.

13. Now analyze the modal analysis data.

14. After that do the model response spectrum analysis.

15. Now Again will check the load combinations.

16.Now run the analysis.

17. Now check the model participation ratios.

18. Now look at the story response.

19. Now we added the base shear to the modeling.

20. Now check the entire analysis of the modeling

• Modal mass participation for the first 3 modes dominates at least 65% (Achieved for X-axis only)
• Mode-1 and Mode-2 differ by 10% (Achieved)
• Principal modes are greater than Torsional mode (Achieved)
• Inter story drift ratio limited to 0.004 (Achieved)
• Axial stress in Column and Shear wall (Achieved)
• Base shear share between shear wall & Columns (Not dual system)

......................................................THE END.....................................................................................................