Modelling of 25 storey building with the specified properties using ETABS

Aim: To model a 25 story building with specified property by using Etabs.

Procedure:

Step1:

• First set the girds according to parameters of the given building plan

From the define story input add the story levels (plinth 1.5m and each story as 3m). All above level are similar to that.

Step3:

To define material property:

• From the define tab select the material property
• Assing the concrete grade as M30
• Assing the rebar grade as Fe415

Define > selection > properties > frame selection

By using rectangle concrete elements define Beam of size 300x400mm as given in plan

By using rectangle concrete elements define Column of size 800x800mm as given in plan by default assumed cover rebar details have been mentioned

Define > selection > properties > slab selection

Using the member property slab size of 150mm is added details as shown

Step 4:

Define > load patterns

By using default dead load, live load, seismic load in in x direction and in y direction assign as per IS 1893:2016

Define > mass source

Mass source data is define as the reduced live load and dead loads are consider for the mass source total weight of the is necessary to calculate the seismic load

Define > load combination

As per IS 456 and 1893 default load combination is generated in Etabs predefined set

Step 5:

By using the quick draw column tool all the columns have model by all story option ON.

By using the quick draw Beans tool all the Beams have model by all story option ON.

By using the quick floor option tool all the slabs have model by all story option ON.

Step 6:

Select > object type > floor

Select all the floors assign the live load of 3kn at all the stories

Select > object type > Beam

Select all the beam assign the frame load with wall load of 10 kn/m at all the levels

Assign > shell > diaphragm

Adding the diaphragm center of the mass for floor can be calculated automatically

Step 7:

Now run the analyze the model structure is verified without error and waring.

Step 8:

Checking for the results.

• Check if the translational fundamental natural period of vibration in both the x and y direction is approximately: Tx1Tx1= 4.4 second Ty1Ty1= 4.2 second
• Check if the following provision in Table 5 of IS 1893 (part 1) – 2016, on torsional irregularity satisfied:

• Check if the two provisions of clause 7 in Table 6 (shown below) of IS 1893 (part 1) – 2016, regarding vertical irregularity is satisfied.

Mass participation for first three mode is

• Check if provision on inter-storey drift limitations in clause 7.11.1.1 satisfied. Please note that this check is for Serviceability Limit State and hence is for situation when stucture is subjected to unfactored seismic base shear