Modelling of 25 storey building with the specified properties using ETABS

AIM -

Challenge – ETABS modelling of a 25 storey building

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.

Carry out the following exercises:

• Check if the translational fundamental natural period of vibration in both the x and y direction is approximately: Tx1">Tx1Tx1= 4.4 second Ty1">Ty1Ty1= 4.2 second

This check will help confirm if modelling is done correctly. Some deviations from the above values is possible (± 2%). But any major deviation will suggest an error in modelling.

• Check if the following provision in Table 5 of IS 1893 (part 1) – 2016, on torsional irregularity satisfied:

The natural period corresponding to the torsional mode of oscillation must be less than the two fundamental translational modes of oscillation along each principal plan directions.

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

• 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

ANS - OPEN A NEW PROJECT/MODEL -

To open a new project or model click on file and open a new project.after that set a display unit - metric si, region is default material -india, steel section data base - indian, steel design code - is 800:2007, concrete design code is456:2000. after that click on ok. and it open a new window. fro grid syestem data.

Grid Syestem Data -

For grid setting used custom grid spacing and custom story data.after that click on grid edit data it opens a another new window. grid syestem data.

after that provide a name (g+5) syestem data. after that set a five A TO E coordinate in x direction in meter.

and also provide in y ordinate a four grid. all grids having a 4meter spacing beetwen them. and select ok.

after completeing a custom grid spacing. open a edit story data. it op-ens a window about what is the name you want to provide to the story and heigjht between them.

from base to plinth i am provide a 1.5m height.

assign a story 1 as a master storey.

after that for adding or creating total 25 storey right click on to storey right side play symbol and add a another 22 storey for creating total 25 storey of the model

After clicking on ok it will open a two window that is plan view of 25th building storey and 3d view of model.

DEFINE MATERIAL -

FOR Adding material click on define option who are top of the ribbon. and click on material properties and

click on adding new material.

after that select material type, region, standard and grade also. and click ok.

After that assign FE-415 hysd reinforcement also

SECTION PROPERTY/ FRAME SECTION -

Select setion property in frame section from for adding new property or frame. select a add new property.

after click on add new property it shows the various section of concrete member steel member

for beam i select concrete rectangular shape member. which is first one.

MOMENT INERTIA- IN Modifieng select moment of inertia as a full.

after clicking ok beam is added as a 300x400

aftyer that adding a column which is 800x800.

IN ETAB SELECT A NAME C800X800. AND SELECT A m30 grade OF COLUMN.

AND CHANGING ITS SIZE.

AND SELECTING REINFORCEMENT IS 4I5 HYSD. FOR COLUMN.

SLAB SECTION -

TO Add slab section select a section from define and select a section as a slab section. and after that select a add new property.

After that change its property name. and use M30 Grade of concrete, after select a slab as a membrane,and change its thiockness as a 150 mm and click ok.

LOAD PATTERN -

Select a load pattern from define option which is located in a define option. and select load along withn the load also select a type and load also.

AND Adding a load pattern dead load, live load, wall load, eartquake in x direction, and in y direction

also add the type of load for x and y direction is seismic load and add is 1893:2016 code

for seismic load x and y direction modified a latteral load in particular direction. if i select a y direction seismic load then i am using a y direction load. after that select seismic zone (3) which have a (.16) value. also select response factor R (5) SAME CONDITION applie in a x direction also and click ok.

MASS SOURCE -

Select and modified how much mass should be consider for the seismic latteral moment. so that select a mass pattern from define option. and click on modified mass source.

and add a dead load as 1, live load according to is code is .25, and super imposed load 1.

CREATE A LOAD COMVBINATION - Creating load combination for concrete frame. select a load combination from define option and select a concrete farme design. click ok.

DRAW COLUMN -

For drawing column select quick drtaw column from left side of the etabs softaware . after that it open a window in that window select a size of the column and draw to all storey.

select a grid and after that column will appear in the all storey.

DRAWING BEAM -

For drawing beam select a quick draw beam option from right side of the window. and create a beam at x and y direction of the total storey building.

DRAW A SLAB -

To draw a slab select a 1storey which is a master storey and and select a quick draw slab and after that select a frame oe slab pattern which i select or created. which is slab 150 mm.

after that select a rectaguar section of the bulding and it will create a floor slab wich have 150mm thickness along the all store.

ASSIGN FRAME LOADS -

To assign frame loads select all beams from properties farme option. and after that assign a distributed frame load and select a wall ( super imposed load ) which i applied 10kn. click apply and then ok.

APPLIED LIVE LOAD AT SLAB SECTION -

Applied live load for slab select a all the slab from slab section and use applied a live load

FOR Applie live select uniform shell section and applie 3kn live load.

AASIGN DIAPHRAGM'S -

for assign a diapharg's select a slab from properties and slab section.

After that aasign a dipharagm's select a shell and after that select a diphragm's and select a D1.

which is very much useful for the latteral calculation.

after selecting ok this window will be appear.

Annalysis -

For annalysis click on annalysis play symbol and after that the model is shown like deflected shape. and annalysis got completed.

THE Following Excercise which i have done .

Desirable solution Ecercise Result

1. funadamental transational natural period in -x direction 4.4 sec. 5.19 sec.

y - direction 4.2 sec. 5.69 sec.

2. Torsional irregularity - is 1893:(part 1) torisional time period mode should be lesser the yes

table 5. then x and y direction time period.

3. vertical irregularity - is 1893:(part 1) first three modes together should contribute atleast yes

table (6) clause (7) 65% in mass participation factor in each principal direction.

fundamental latteral natural periods in two principal plan no

direction are away from each other by atleast 10%

4. Inter storey Drift - is 1893:(part 1) storey drift shall not exceed 0.004 times the storey height yes

clause 7.11.1.1 for base shear with no load factors `(4*10^-3)`

for EQX

FOR EQ Y