Structural Modelling using Etabs 2018
1)AIM:
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,mat um 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.
ans)
procedure:
1. open the etabs software.
2. click on the file option at the left side top corner and select the new model, as shown below.
3. the new tab opens, in that tab we have to select 'Use Built-in Settings with option, as shown below.
4. Next we need to do the settings in Grid system data, as shown below.
5. add the stories upto 7 story in the Story Data, as shown below. The 7 stories are added in the Story Data, as shown below.
6.plan views are visible in the etabs screen, as shown below. Next we need to open the 3d-view, as shown in the below figure.
7.we need to define option and select material properties
8. then we add new materials by selecting the Add new material option.and add material type as concrete and grade as M25.
9.add new material type as rebar and grade as HYSD Grade 415.and add new material type as rebar and grade as HYSD Grade 500.
10. select the section properties and click on the frame sections, as shown below.select the Rectangular shape type in concrete.add beam size as B250x450, as shown below and Modify/Show Rebar option as shown below.
11.Next we select longitudinal bars with the grade of HYSD500 select Confinement bars with the grade of HYSD415.
12. we add column size as B300x500, Modify/Show Rebar option as shown below.
13.Next we select longitudinal bars with the grade of HYSD500 select Confinement bars with the grade of HYSD415.
14. we have to add the column size as 400x400 in the frame section property data.Again we have to add the another column size as 400X600 in the frame section property data, as shown below.
15.we select the slab section option from the section properties, as shown below.
16.the slab name as Slab 125, it means slab with the thickness of 125mm.
17.Now we take the slab thickness separately for staircase with the thickness of 200mm, as shown below.
18. we have to add the wall properties in the wall property data, as shown below.
19. we need to add the columns using the Quick draw columns option, as shown below.
20.we need to add the beams using the Quick draw beams option, as shown below.
21. we need to add the secondary beams using the Quick draw beams option, as shown below.
22. we add the shear walls in required locations in the residential building, as shown below.
23. we need to add the slabs using the Quick draw floor/wall option, as shown below.
24.select all base joints. Next we select the Restraints from joint option, as shown below.
25.Make the fixed joint and click on apply and then click on close button, as shown below.
29. select the load patterns from the define option, as shown below.add Dead load, live load, Brickwall load, and earthquake load, as shown below.select the distributed load from the frame loads, as shown below.
30. select load pattern as Brickwall, and we take uniform load as 3.5 kN/m and then click on the apply button and close.
31.click on the assign option and then select shell loads, from the shell loads we select the Uniform option, as shown below.
3kN Here we apply the live load for the staircase portion, varanda, and lift core area. m²
2kN- Next we lipply the live load for the remaining portions in the residential building, as shown below
32. select live load reduction factors from the design aption, as shown below. Now we add the reduction factor by decreasing 10% from 1st floor to 7th floor
33.we add the load patterns in the Mass Source Data as shown below
34. select the Diaphragms from the shell option select the Pier label from the shell option as shown below.assign the names for the shear walls (PS P2, P3 P4 P5 P6,P7 PB, as shown below
35.we select the load combinations.After selecting the load combinations the new tab is visible, In that we select 'Add Default Design Combos' option.
36.select "concrete frame design" & "concrete shear wall design in the 'Add Default Design Combinations, as shown below.we can see here that the load combinations are visible, as shown below.
37.select the Modal cases from the Define option, as shown below. give modal case name as Modal 1 & we give the maximum number of modes as 20, as shown below.check the model by clicking the check model option, as shown below.
38.then the warning tab will be visible and it tells that there is no warning messages, as shown below.
39.select the Response spectrum from the Functions from define option, as shown below. choose IS 1893 2016 from the Choose function type' and click on the Modify/Show spectrum option, as shown below.
40. Function name as 'IS FUNCTION and remaining details will be set by the software itself, we don't need to change any of the details in that response spectrum function tab, as shown below.
41.select the Load cases from the Define option, as shown below. Next the Load cases tab will be visible, In that we select the 'Add new case, as shown below.
42.we have to do the run analysis, as shown below.
results:
