Structural Modelling using Etabs 2018

ANS:-

• Open the ETabs software.
• Click the file menu and choose to create a new model option.
• After choosing a new model a dialogue box will appear as Model Initialization.

• Choose the built-in settings option and select the display units and codes.
• New dialogue box will appear named New Model Quick Templates.
• Select Custom Grid spacing and custom story data.

• After models initialization, select grid and storey inputs from new model quick templates dialogue box.
• In the dialogue box choose grid spacing and custom story data which is used to provide the input specified above.

• Now edit stories by using the user-defined story input, 26 stories are incorporated (plinth at 1.5m and 25 story with 3m height each).
• Storey 1 has been labelled as a master storey and all above levels are labelled similar to that.

• Add Story height as 3m.
• Number of Added stories as 4.

• So, 7 storeys are successfully added in the peoject.
• Create alll the storeys as similar to storey 1.

• Select Material properties under define tab.

• New dialogue box will appear named Define Materials.
• Select Add new Material from the window.

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

  

  • Now need to add material type as concrete and grade as M30.
  • Now we need to check the material property data, as shown below.

  

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

  

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

  

  • Now select Section Properties under Define Tab.
  • Select Frame Sections.
  • Select Add new properties in Frame Properties.

  

  

  • Create a new Property as a beam and input values as 250X450.
  • Select Modify/Show Rebar in Reinforcement option.
  • Select M3 Design only (Beam).
  • Select Reabar as HYSD415.

  

  

  • Create a new Property as a beam and input values as 300X500.
  • Select Modify/Show Rebar in Reinforcement option.
  • Select M3 Design only (Beam).
  • Select Reabar as HYSD415.

  

  

  • Create a new Property as a column and input values as 400X400.
  • Select Modify/Show Rebar in Reinforcement option.
  • Select P-M2-M3 Design (Column).
  • Select Reabar as HYSD415.

  

  

  • Create a new Property as a column and input values as 400X650.
  • Select Modify/Show Rebar in Reinforcement option.
  • Select P-M2-M3 Design (Column).
  • Select Reabar as HYSD415.

  

  

  • Now select Section Properties under Define Tab.
  • Select Slab Sections.
  • Select Add new properties in Slab Properties.

  

  

  • Using the membrane properties, slab size 125 mm has been added to the list.
  • Membrane property will help to consider only slab weights and Floor weights in analysis of structure while no stiffness component of flange advantage are considered during calculation.

  

  • Using the membrane properties, slab size 200 mm has been added to the list for staircase.
  • Membrane property will help to consider only slab weights and Floor weights in analysis of structure while no stiffness component of flange advantage are considered during calculation.

  

  • Now we have to add Wall properties in wall property data.

  

  • Now add the wall data as thickess of the wall as 250 mm, Material- M25.

  

  • Now add the wall data as thickess of the wall as 300 mm, Material- M25.

  

  • Now Draw columns of size 400X400 mm at the intersection of the horizontal and vertical grids and beams with quick draw Column keeping all the stories on.

  

  • Now draw columns of size 400X650 mm at the intersection of the horizontal and vertical grids and beams with quick draw Column keeping all the stories on.

  

  • Columns are Successfully added to the structure.

  

  • Now Draw the Beams.
  • Draw beams of size 250X450mm at the intersection of the horizontal and vertical grids and beams with quick draw beam keeping all the stories on.

  

  • Beams are Successfully added to the structure.

  

  • Next we have to Draw secondary beams.

  

  • Next we add the shear walls in required locations in longitudinal building.

  

  • Now Draw the Slab.
  • Draw slab of size 125mm thickness, Draw slabs with quick draw floor/wall keeping all the stories on.

  

  • Slabs are Successfully added to the structure.

  

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

  

  • Now define the Load patterns.
  • Click on the define tab and click on load patterns.
  • Define the loads like dead load, live load, brick load, earthquake load in X direction and same loads in Y direction also.
  • Mention IS codes of respective loads.

  

  

  • Next we need to select the distributed load from the frame loads.

  

  • Then after the new tab will appear, in that case we select load pattern as Brickwall and we take uniform load as 3.5 Kn/m an then apply.

  

  • Next we have to click on assign option and then select shell loads and select Uniform option.

  

  • Here we apply 3 Kn/m2 live load for the staircase portion, verandah and liftcore area.

  

  • Here we apply 2 Kn/m2 live load for rest of the portion in the slabs.

  

  • Next we add live load reduction factor from the design option.

  

  • Now add the reduction factor as decrease of 10%from 1st to 7th floor.

  

  • Now go to Mars Source from define tab.
  • Modify the mars source and tick mark the required loads.
  • Add load patterns and assign the model.
  • Insert the dead load as multiplier to 1, live load as multiplier to 0.25 and wall load as multiplier to 1.

  

  

  • Mars source is been added successfully.

  

  • Now go to Load cases in define Tab.

  

  

  • Now create the Diaphragm by going to the assign tab then shell and select diaphragm.

  

  

  • Next we have to select the pier lable from shell option.

  

  • WE have to assign the names for the shear wall.

  

  • Now go to Load combinations in define Tab.

  

  • Select add default design combos.
  • Select concrete frame Design.

  

  

  • Next we add model cases from define option.

  

  • Give odeal case name as Model1 and we give the maximun number of modes as 20.

  

  • Next we need to check the Model.

  

  • After the model is checked, it will show us No warning.

  

  • Now select the response spectrum from Functions option in define Tab.

  

  • We choose IS 1893:2016 from choose function Type and click on Modify/Show spectrum option.

  

  • Now go to Load cases in define Tab.

  

  

  • Add new case.

  

  • Analyse the model using analyse option then click on check model the modelled structure is verified without errors and warnings.

  

  

  • Now click on display -> show tables -> Analysis result structure output -> Base Reactions

  

• We have to check EQ should be close to the RS , We need to do some calculations.
• Now we put above value as scale factor for Response Spectrum at X and Y direction.

• Now click on display -> show tables -> Analysis result structure output -> model information -> model periods and frequencies.

• Select the Story Response Plot from Display option.

• Story Response for maximum Story Drifts for x and Y direction is as per following.

X- Direction :-

Y- Direction :-

• Next we open the Base floor in Plan view.

• We have to open Reaction tab, we select the earthquake load towards in X-direction in load case.

• When we divide base shear taken up by shear wall divided by total base shear of Building will get % of shear forces taken by Shear Wall.