Structural Modelling using Etabs 2018

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.

AIM:

To create a model of G+7 building using ETABS, given The architectural drawings for a G+7 residential building in zone 5. The structural model must comply with provisions of IS 1893 and IS 13920.

To Run a modal response spectrum analysis and check analysis results of the etabs model.

Procedure:

Step1:-

• Open the etab software.
• Then select the new modal.
• After that the new tab will open and select the Use built-in setting and press ok.
• Then new modal quick template will open and select the grid only and press ok
• Then we need to do the settings of grid system data.
• Then add the stories, the 7 stories are added with roof in the story data.

Step2:-

• The plan view are open in the screen of etabs.
• 3d view are also open in the screen of etabs.

Step3:-

• Go to the save option and save the project.

Step4:-

• Then go to the define option and select the material properties.
• After selecting material properties the new tab will open, then we add new material by selecting add material.

Step5:-

• Then add material type as concrete and grade as M25.
• Then we need to check material property data.

Step6:-

• Then we need to add new material type as rebar and grade as HYSD grade 415.
• Then add HYSD grade 500.

Step7:-

• Then go to define then select section properties then select frame section and then select add new property.
• The new tab will appear the select rectangular concrete shape the add the details of beam.
• We add 250x500 beam, and 300x500 beam.

Step8:-

• The step we follow in the adding of beam repeat same for the column.
• Add Column of size 400x400 and 400x600.

Step9:-

• Next for slab
• Go to the define then select section properties then select slab section and then add new.
• Add Slab 115mm thickness and for stair slab 200mm thickness.

Step10:-

• Then go to define select section properties the select wall section and the add new wall.
• Then we have to add 250mm wall.

Step11:-

• Then add the columns using the quick draw column option.
• Next we need to add the beams using quick draw tool.
• Then add the secondary beams using the quick draw beams option.
• Add the shear walls in the required location of building.
• And then add the slab using quick draw floor/wall option.

Step12:-

• Now we go to the base plan and select all base joints.
• Next we select the Restraints from joint option.
• Now we need to select the fixed joint and click on apply and then click on close button, as shown below.

Step13:-

• Then select the load patterns from the define option.
• Add Dead load, live load, Brickwall load, and earthquake load.

Step14:-

• Select the distributed load from the frame loads.
• New tab will appear, in that select load pattern as Brickwall, and we take uniform load as 3.5 kN/m and then click on the apply button and close.

Step15:-

• Then click on the assign option and then select shell loads, from the shell loads we select the Uniform option.
• Then apply the live load for the staircase portion, varanda, and lift core area.
• Next apply the live load for the remaining portions in the residential building.

Step16:-

• Next we have to select live load reduction factors from the design option.
• Add the reduction factor by decreasing 10% from 1st floor to 7th floor.

Step17

• Then from the define option we select the mass source.
• Add the load patterns in the Mass Source Data.

Step18:-

• In the select option we select object type option.
• After selecting the object type option, the new tab will be visible. In that select the floors and click on the select button and close.
• Next we have to select the Diaphragms from the shell option.
• After selecting the diaphragms the new tab will appear, in that select D1 and click on the apply button and close.

Step19:-

• Then select the Pier label from the shell option.
• Before going to the shear wall design we have to assign the names for the shear walls(PLP2 P3 P4 P5 P6 P7 P8).

Step20:-

• From the define option we select the load combinations.
• After selecting the load combinations the new tab is appear In that select Add Default Design Combos option.
• Then select "concrete frame design & concrete shear wall design in the Add Default Design Combination.
• Now we can see here that the load combinations are appear.

Step21:-

• Now select the Response spectrum from the Functions from define option.
• After selecting the Respnse spectrum the new tab is visible, in that we choose IS 1893 2016 from the Choose function type and click on the Modify/Show spectrum option.
• Then selecting the modify show spectrum option the new tab will be visible. In that we give the Function name as 15 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.

Step22:-

• Now select the Load cases from the define option.
• Next the Load cases tab will be visible, In that we select the Add new case.
• Now enter the details of load case in the load case data.
• Now we have to do the run analysis

Step23:-

• Next, from the display option select the show tables option.
• After selecting the show tables option the new tab will appear.
• Now we select the Base Reactions and click on the ok button.
• The Base Reactions table will be visible.
• Here we have to check that EQ should be closer to the RS. to get the closer to each other we should calculate that [(EQ/RS) * Scale factor of Response spectrum.]
• After enter these values for response spectrum as scale factors at X and Y directions in load case data, then the EQ is closer to the RS from the base reaction table.

Step24:-

• Then from the display option select the show tables option.
• 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.
• Now the Modal Parbopating Mass Ratio table will be visible.

Step25:-

• Next select the Story response plots from the Display option.
• The story response for max story drift at X and Y direction, should not be more than 4%.

Step26:-

• Next open the select plan view tab and select the base floor.
• Next we have to open the reactions tab, then we select the eartquake load towards X-direction(EQX) in the load case, then click on the ok.
• Now the base shear reactions will appear.
• When we divide the base shear taken up by the shear wall divided by the total base shear of building will get the % of the shea forces taken up by the shear wall.
• And if that is less than 80%, then the more shear walls we need to add to the structure.

RESULT:-

Therefore, the G+7 building has been modeled with all the required conditions as per Residential building and has been analysied succesfully using ETABS.