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Challenge

Structural Modelling using Etabs 2018

AAnil Ninawe26 Jan 2023

Aim:-

The architectural drawings for a G+7 residential building in zone 5 have been provided. The floor plan is the same for all 7-floor levels.

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 structure class.
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.

Step:-1

First we have to open the tabs software.
Next click on the file option at the left side top corner and select the new model, as shown below.

After that select, the new model the new tab opens, in that tab, we have to choose the 'Use Built-in Settings with' option, as shown below.

After, setting the model Initialization the templates tab will opens and, select the Grid only and press ok.
Next we need to do the settings in the Grid system data, as shown below.

Next, we need to add the stories up to 7 levels in the Story Data, as shown below.
The 7 stories are added in the Story Data, as shown below.

Next, the plan views are visible on the etabs screen, as shown below.
Next, we need to open the 3D view, as shown in the below figure.

Next, we need to define tab option and select material properties, as shown below.

After selecting the material properties the new tab appears, then we add new materials by selecting the Add new material option, as shown below.

Now we need to add material type as concrete and grade as M25.
Next, we need to check the material property data, as shown below.

Now we need to add a new material type as rebar and grade as HYSD Grade 415.
Next, we need to check the material property data, as shown below.

Now we need to add a new material type as rebar and grade as HYSD Grade 500.
Next, we need to check the material property data, as shown below.

We need to select the section properties and click on the frame sections, as shown below.

After selecting the frame sections the new tab will be visible, in that we need to select the Add New Property, as shown below.

After selecting Add New Property, the new tab appears.
In that new tab, we select the Rectangular shape type in concrete, as shown below.

Next, the frame section property data will be visible, In that, we add the beam size as B250x450, as shown below.
Next, we need to select the Modify/Show Rebar option as shown below

After selecting the Modify/Show Rebar option the new tab appears, In that we select the design type as M3 Design only (Beam).
Next, we select longitudinal bars with the grade of HYSD500.
Next, we select Confinement bars with the grade of HYSD415.
Again we have to select the Rectangular shape type in concrete, as shown below.

Next, the frame section property data will be visible, In that, we add a column size of B300x500, as shown below.
Next, we need to select the Modify/Show Rebar option as shown below.

After selecting the Modify/Show Rebar option a new tab appears, In which we select the design type as M3 Design only (Beam).
Next, we select longitudinal bars with the grade of HYSD500.
Next, we select Confinement bars with the grade of HYSD415.

Next, we have to add the column size as 400X400 in the frame section property data, as shown below.

Again we have to add another column size C400X600 in the frame section property data, as shown below.

Next, we select the slab section option from the section properties, as shown below.

Next, the slab properties tab will be visible, In that we select the Modify/Show Property option, as shown below.

After selecting the Modify/Show Property option, the new tab appears.
In that, we need to put the slab name as Slab 125, which means slab with a thickness of 125mm.
And we take the concrete grade as M25, as shown below.
Next, we have to click the ok option.

Now we take the slab thickness separately for the staircase with the thickness of 200mm, as shown below.

Next, we have to add the wall properties in the wall property data, as shown below.

Next, we need to add the columns using the Quickdraw columns option, as shown below.

Next, we need to add the beams using the Quickdraw beams option, as shown below.

Next, we need to add the secondary beams using the Quickdraw beams option, as shown below.

Next, we add the shear walls in the required locations in the residential building, as shown below.

Next, we need to add the slabs using the Quickdraw floor/wall option, as shown below.

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

Next, we need to select the load patterns from the define option, as shown below.

Now we should add Dead load, live load, Brickwall load, and earthquake load, as shown below.

Next, we need to select the distributed load from the frame loads, as shown below.

Then after the new tab will appear, In that we select the load pattern as Brickwall, and take the uniform load as 3.5 kN/m, and then click on the apply button and close.

Next, we have to click on the assign option and then select shell loads, from the shell loads we select the Uniform option, as shown below.

Here we apply the 3KN/m^2 live load for the staircase portion, veranda, and lift core area.
Next, we apply the 2KN/M^2 live load for the remaining portions of the residential building, as shown below.

Next, we have to select live load reduction factors from the design option, as shown below.

Now we add the reduction factor by decreasing 10% from the 1st floor to the 7th floor, as shown below.

Next, from the define option we select the mass source, as shown below.

Next, we add the load patterns in the Mass Source Data, as shown below.

In the select option, we select the object type option, as shown below.

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, as shown below.

After selecting the diaphragms the new tab will appear, in that select D1 and click on the apply button, and close.

Next, we have to select the Pier label from the shell option, as shown below.
Before going to the shear wall design we have to assign the names for the shear walls(P1, P2, P3, P4, P5, P6, P7, P8), as shown below.

Next, from the define option we select the load combinations, as shown below.

After selecting the load combinations the new tab is visible, In that, we select the 'Add Default Design Combos' option.
Next, we select "concrete frame design" & "concrete shear wall design" in the 'Add Default Design Combinations', as shown below.
Now we can see here that the load combinations are visible, as shown below.

Next, we select the Modal cases from the Define option, as shown below.
After selecting the Modal cases the new tab is visible, In that, we give the modal case name as Modal 1 & we give the maximum number of modes as 20, as shown below.

Next, we have to check the model by clicking the check model option, as shown below.

After the model is checked, then the warning tab will be visible and it tells that there are no warning messages, as shown below.

Now we select the Response spectrum from the Functions from the define option, as shown below.
After selecting the Response 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, as shown below.

After selecting the modify/show spectrum option the new tab will be visible, In that we give the Function name as 'IS FUNCTION' and the 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.

Next, we have to select the Load cases from the Define option, as shown below.
Next, the Load cases tab will be visible, In we select the 'Add a new case', as shown below.

Now we have to enter the details of the load case in the 'Load case data', as shown below.

Now we have to do the run analysis, as shown below.

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 Base Reactions and click on the ok button, as shown below.

Next, the Base Reactions table will be visible, as shown below. Here we have to check that EQ should be closer to the RS, to get the closer to each other we should calculate that, (EQRS)×">((EQRS)×">EQ/RS)×Scale factor of the Response spectrum. Now substituting the values from the table,

X-direction (2095.4592/1478.7478)*(9806.65)

Y-direction (2844.63481002.1982)×9806.65">(1619.6233/1108.66)×9806.65

(2844.63481002.1982)×9806.65">

At X-direction, we get 13896.52
At Y-direction we get, 14326.389
We put the above values as scale factors for the response spectrum in X and Y directions in the load case data.
After we enter these values for the 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, as shown below.

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

Next, we open the select plan view tab and select the base floor, as shown below.

Next, we have to open the reactions tab, then we select the earthquake load towards X-direction(EQX) in the load case, then click on the ok button as shown below. Now the base shear reactions will appear, as shown below. When we divide the base shear taken up by the shear wall divided by the total base shear of the building will get the % of the shear 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:-

The G+7 residential building has been modeled and analyzed successfully using the ETABS 2018.

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