Structural Modelling using Etabs 2018

Aim:- To model and analyze the G+7 residential building from the given architectural drawings using the ETABS 2018.

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 class of structure.
• 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.

Procedure:-

Step:-1

• First we have to open the etabs software.
• Next click on the file option at the left side top corner and select the new model, 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.

          

Step:-2

• Next the 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.

Step:-3

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

Step:-4

• Now we need to add material type as concrete and grade as M25.

Step:-5

• Now we need to add new material type as rebar and grade as HYSD Grade 415.

Step:-7

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

Step:-8

• 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 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.

Step:-9

• Again we have to add the  column size as 450X600 in the frame section property data, as shown below.

Step:-10

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

Step:-11

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

Step:-12

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

Step:-13

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

          

Step:-14

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

          

Step:-15

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

          

Step:-16

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

          

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

Step:-19

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

         

tep:-20

• 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, varanda, and lift core area.

• Next we apply the 2kN/m^2 live load for the remaining portions in the residential building, as shown below.

Step:-21

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

         

Step:-22

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

         

Step:-23

• 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. 

Step:-24

• Next we have to select the Pier label from the shell option, as shown below.

step:-25

• 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.

Step:-26

• 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.

Step:-28

• 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.

Step:-29

• 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 do the run analysis, as shown below.

Step:-30

• 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.

• 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.

Step:-31

• 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.

         

Step:-32

• 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%.

Step:-33

• 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 building has been modelled and analysized succesfully using the  E-TABS.