Challenge

Modelling of 25 storey building with the specified properties using ETABS

SShubham Ojha21 Mar 2023

Model a 25 storey building on ETABS with structural properties as specified below. Ground floor or plinth floor level can be taken at a height of 1.5 metres from the base. Each of the successive 25 storeys has a storey height of 3 metres.

Structural Element Sizes

Beams : 300 × 400 mm
Columns : 800 × 800 mm
Slab : 150 mm thick

Material Properties

Grade of Concrete : M30
Grade of Steel Reinforcement Bars : Fe 415

Loading

Dead Load on beams from infill wall : 10 kN/m (Let us assume the same for roof floor in view of parapet)
Live load on floor : 3 kN/m2 (Let us assume the same for roof floor)

a) Buildings are assumed to be pinned at the base

b) All columns in all storey are of the same size

c) All beams in all storeys are of the same size

d) Building is located on Soil type-II and in Zone-III. Assume other factors if required.

AIM........................................................

to model and analyse a 25 storey building with given specifications and to cross check the parameters as per IS 1893 provisions.

Procedure:

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 intialization.

Choose the built-in settings option and select the display units and codes.
After model intialization select the grid and story inputs from the New model quick templates dialogue box.
In this dialogue bchoose ctom grid spacing and custom story datata which is used to provide the inputs specified above.
Enetr X grid data at a distance of 4 metreand Y grid data as 4 at a distance of 4 metre.

Now edit the stories by using the user defined storey input,26 storeys are incorportaed , plinth at 1.5 meter height+ 25 storey with 3 meter height each, . Storey 1 has benn labelled as master storey and all above levels are labelled similar to that.

Select mterial properties under the define tab.../.
Define the materials of concrete M30 grade and steel of transverse reinforcement as 415 grade

Select Section properties under the define tab.
Click on the frame section and create a new property as beam and input the values as 300X400mm.

After the define properties for the column 800X800

Using the membrane property,slab size 150mm has been addded tothe list.Mebrane 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 draw a column of size 800X800mm at the intersection of the horizontal and vertical grid and beams with quick draw tool keeping all stories on.

Beams drawn using quick draw beam tool keeping all the stories on.

Using the quick draw fllors option all the slabs have been modelled keeping similar stories on

Select assign and click on joint select pinned support.
Fix he pin supports at the base.

Now define the load patterns: click on the define ta and click on load patterns.
Define the loads like dead load,live load,brick load,earth quake load in x direction and positive x and negative x and same loads in the Y direction also.Mention IS codes of respective loads.

Click on modify lateral load,set range from base to 25th storey and seismic zone factor as 0.36,importance factor 1 and time period 0.5 seconds.

Do the same for all the earthquake loads.
Assign the loads and select similar stories.
Click on shell load under the assign tab.
Click on live load and give value as 3kn/m^2.
Click on apply.

Similarly add live load of 10Kn/m^2 on all the beams.
For that select all the beams from select object type beams.
Goto the frame load and click on the distributed load and enter the value as 10 Kn/m^2.