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.

Please note that the column positions shown in the architectural typical floor plan are only to provide an initial starting point for modelling. Participants will have to change its size, introduce shear walls, and add new vertical elements after running the analysis. You will have to run the analysis multiple times until a structural model is obtained that meets structural code requirements without compromising architectural functions. Also, there is no one ‘correct’ structural system for this challenge. There can be multiple possible solutions for this problem.

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.

AIM:

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

• Open ETABS and select New Model option from the File menu
• Now set the Use Built in setings with Options

• 
• Now set the Grid systems data and add 7 storeys with an addition of plinth
• 
• 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.

• Next we need to define option and select material properties, as shown below.
• Now select the Material properties from the Define menu and add New material as concrete M25 and Rebar HYSD 415 , 500

• 
• Now select the section properties and select the frame section, now select Add new property, select the shape and add beam of required size (250*450)
• 
• 
• Now select Modify/Show Rebar option and select M3 design only , and select Longitudinal bars with HYSD Grade 500 and the confinement bars(ties) with HYSD Grade 415
• Now again select the section properties and select the frame section, now select Add new property, select the shape and add beam of required size (300*500)
• Now select Modify/Show Rebar option and select M3 design only , and select Longitudinal bars with HYSD Grade 500 and the confinement bars(ties) with HYSD Grade 415
• 
• Now select the section properties and select the frame section, now select Add new property, select the shape and add column of required size (400*400)
• Now again select the section properties and select the frame section, now select Add new property, select the shape and add column of required size (400*600)
• 
• Now from the Define menu, select Section properties and select Slab section
• Select Modify/Show property, give a new slab name and mention the thickness as 125mm and slab material as M25 and click ok
• 
• Now define a new slab for the staircase, with thickness 200mm and slab material as M25.
• Insert 250mm thickness in the wall property data and click ok with the wall material as M25
• 
• Using Quick draw columns, draw the columns
• And now use quick draw beams, draw the beams. Now draw the secondary beams using Quick draw beams option
• 
• Now add the shear walls at appropriate location as given in the plan.
• Now using Quick draw floor/wall option, draw the slabs
• 
• Now select the base joints and select Restraints from Joint option of Assign menu, and fix the joints and click ok
• Now from the define menu, define the load patterns as Live load, dead load, brickwall load, earthquake loads.
• Now select the frame loads from the assign menu, and slect Distributed loads, and take a uniform load of 3.5 KN/m and close it
• Now from the Assign option, select the shell load and select Uniform and apply 3KN/m^2 for staircase, life etc
• Now from the Assign option, select the shell load and select Uniform and apply 2KN/m^2 for the rest of the building
• Now from the Define menu, select mass source and add the load patterns
• Now from the Select option of the Select Menu, select Object type and select the floors, and click select and then click,
• Select the shell option and select Diaphragms from it, select D1 and click on the apply button and close
• 
• Now from the Assign Menu, select Pier label option from the shell option
• Now from the define option, select the load combination and select Add Default Design combos
• Now select the concrete frame design and concrete shear wall design in the Add default design combinations
• Now from the Define option, select Modal cases, and give modal case names as Modal 1 and give the maximum number of modes as 20
• From the Analyze menu, select check model, and now the warning tab appears
• Now from the Define option, select Response spectrum and choose IS 1893:2016 .
• Now click on Modify / show spectrum option, and give an identical function name.
• From the Define menu, select Load cases and select Add new case
• Now from the Analysis menu, select Run analysis
• Now select the Design menu, select the concrete frame design and select Start design check
• Now select the Design menu, select the concrete slab design and select Start design check
• From the Display Menu, select Show tables and select Base reactions and click ok
• 
• 

Calculation

• To check if the EQ is closer to RS, we use (EQ/RS)
• Now the structure is reanalysed and checked and found that EQ is almost equal to RS.
• We have to check for both EQx, RSx and EQy, RSy

• Now again select the Display menu and select Storey Response plot and select Inter storey drift(RSx) and then for (RSy). The storey response for maximum storey drifts at X and Y directions should not be more than 4%
• 
• Now again take the Display menu and select show tables and select Modal Participating mass ratio and click ok
• 
• Now from the Display menu, select Force/ Shear diagram and select Shell stresses/ force

RESULT:

Finally we got the Conceptualized a framing plan layout and then modeled the building in Etabs and analysis are done