Challenge

Structural Modelling using Etabs 2018

SShubham Kumar Singh23 Feb 2024

ETABS HTML

ANS:

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.

INTRODUCTION:

ETABS is an engineering software product that caters to multi-story building analysis and design.
Modelling tools and templates, code-based load prescriptions, analysis methods and solution techniques, all coordinate with the grid-like geometry unique to this class of structure.
Basic or advanced systems under static or dynamic conditions may be evaluated using ETABS.
Interoperability with a series of design and documentation platforms makes ETABS a coordinated and productive tool for designs which range from simple 2D frames to elaborate modern high-rises.
Once modelling is complete, ETABS automatically generates and assigns code-based loading conditions for gravity, seismic, wind, and thermal forces.
Users may specify an unlimited number of load-cases and combinations.
Analysis capabilities then offer advanced nonlinear methods for characterization of static-pushover and dynamic response.
Dynamic considerations may include modal, response-spectrum, or time- history analysis.

Procedure:-

First open the etabs software.

Next click on the file option at the left side top corner and select the new model, as shown below.

After selecting the new model the new tab opens, in that tab we have to select '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 Grid system data, as shown below.

Next we need to 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.

The plan view is displayed on the etabs screen as shown below.
Next we need to open the 3D view as shown in the image below.
Next you need to define parameters and select material properties as shown below.
After selecting material properties, a new tab will appear, add a new material by selecting the Add new material option.
Select concrete as material type and M25 as its grade and check the material property data.
Similarly add two new materials for rebars by selecting rebar as material and HYSD grade 415 and HYSD grade 500 respectively.
Now you need to select section properties and click on the frame section.
Define two beam sections of dimensions B250X450 and B300x500 by selecting add new property and selecting rectangular section.
Select M25 in the material drop down, edit the depth and width values. Decrease the values of moment of inertia about axis 2 & 3 to 0.35 and change the tortional constant to 0.001.
Then open the modify/show rebar and select beam in design type.
Assign the respective rebars to longitudinal and confinement bars.
Similarly add two column sections of dimensions C400x400 and 400x600.
Assign M25 as material, change the depth and width value.
Open the modify/show modifiers & change the moment of inertia about 2 & 3 axis to 0.7.
Open the Modify/show rebar settings and assign the respective rebars definitions to longitudinal and confinement bars.
Then select the slab section option in section properties and create two slab sections one for floor areas and one for staircase area of thickness 125mm and 225mm respectively.
Assign slab material as M25 concrete and modeling type as Membrane to both of them.
Now go to wall sections in section properties and create wall sections of thickness 250mm.
In this case the modeling type will be shell-thin.

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

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

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

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

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

Now we go to the base plan and select all base joints.
Next we select the Restraints from joint option, as shown below.

Now we need to select the fixed joint and click on apply and then click on 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 load pattern as Brickwall, and we take 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 3kNm2">3kNm23��2live load for the staircase portion, varanda, and lift core area.

Next we apply the 2kNm2">2kNm22��2 live load for the remaining portions in 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 1st floor to 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 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 '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 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 is no warning messages, as shown below.

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

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, 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 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 that we select the 'Add new case', as shown below.

Now we have to enter the details of 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)×(��)×Scale factor of Response spectrum.
Now substituting the values from the table, at X-direction (2844.6348900.7656)×(9806.65)">(2844.6348900.7656)×(9806.65)(2844.6348900.7656)×(9806.65), at Y-direction (2844.63481002.1982)×9806.65">(2844.63481002.1982)×9806.65(2844.63481002.1982)×9806.65

At X-direction we get, 30969.6
At Y-direction we get, 27835.15
We put the above values as scale factor for response spectrum at X and Y directions in the load case data.
After we 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, 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 select the Story response plots from the Display option, as shown below.

The story response for maximum story drifts at X & Y directions, should not be more than 4%.

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 eartquake load towards X-direction(EQX) in the load case, then click on the ok buttion 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 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 modelled and analyzed successfully using the ETABS 2018.

Structural Modelling using Etabs 2018

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in your own course.

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Ship work like thisin your own course.

Talk to a career counsellor

Ship work like this
in your own course.