Project 2_Design & Analysis of a Hostel building at Guwahati, Assam

1) ETABS is an engineering software product that caters to multi strorey building analysis and design.

2) SAFE represents the state of art in three dimensional finfite element technologies for structural engineering.

3) Here, in this project we are carrying out the design analysis of a G+3 building situated in Guwahati,

Assam using ETABS software and then foundation design is carried out using SAFE software

Step 1)

i) Open the Etabs software from deskstop icon

ii) Once software is open - Click on New model

Step 2)

i) Once you click on New model

ii) A Model Initialization setting will open

iii) Select - Metric SI units

iv) Select section database - Indian

v) Select Steel code - IS 800-2007

vi) Select Concrete design code - IS 456-2000

Step 3)

i) Once you click Okay

ii) A following dialog box of grid settings will open

ii) In New Model Quick templates under grid dimensions select the custom grid spacing

iii) Once you click on Custom grid spacing

iv) Click on Display grid data as spacing

iii) Now input the storey details

iv) As given in question and Story 1 was selected as the Master story

v) Click on Okay .

Step 5)

i) Once you click on Okay

ii) A plan and 3D view of model is created in model space

Step 6)

i) Now we have to define the materia properties

ii) Click on Define

iii) Click on Material properties

iv) Add New material as Concrete

v) Select Grade of conccrete - ...........................( given)

vi) Standard as Indian

vii) Click on Okay .

viii) Click on okay

ix) The remaining data is as per IS code

i) Similarly we have to define the materia properties for Steel

ii) Click on Define

iii) Click on Material properties

iv) Select New material as Rebar

v) Select Grade of Steel - HYHD - Grade Fe415...................... ( given)

vi) Standard as Indian

vii) Click on Okay .

viii) Click on Okay

ix) The remaining data is as per IS code

x) Material properties is added

Step 8)

i) Now we have to Define the section properties ( Column and Beam )

ii) Click on Define

iii) Select - Section properties

iv) Click on Frame Section

v) Click on Okay.

vi) Click on Add new property

vii) Select Rectangular shape

vi) Give property name - Beam 400x500............( given)

vii) Material type - M25

viii) Section Shape - Concrete Rectangular

ix) Depth - 500 mm

x) Width - 400 mm

xi) Click on Modify / show Rebar

xii) Select M3 Design Only (Beam)

xiii) Select the rebar materials as HYHD Fe415 in both the direction

xiv) Click on okay .

xv) Similarly we have to follow the same steps for Column also.

xvi) Property name - Column 550 x 550 mm

xvii) Material - M25

xviii) Depth - 550 mm

xix) Width - 550 mm

xx) Click on Modify / show Rebar

xxi) Select M3 Design Only (Column)

xxii) Select the Rebar materials as HYHD Fe415 in both the direction

xxiii) Click on okay .

Step 9)

i) Now we have to define Slab properties

ii) Click on Define

iii) Select Section Properties - Select Slab properties

iv) Click on Slab Section

v) Give property name - Slab 150

vi) Slab material - M30

vii) Modeling Type - Membrane

viii) Type - Slab

ix) Thickness - 150 mm

Step 10)

i) Now we have keep the 3D view also to see the properties

ii) Now we have to add the columns and beams

iii) Click on Quick Draw Column option

iv) Select the Column properties which we have defined earlier

v) Draw the columns at the grids as shown in below

vi) Note that - All stories option should be selected which is at the Bottom

vii) Similarly we have to draw beams also

viii) Select Quick Draw Beam option

ix) Select the Beam properties which we have defined earlier

x) Draw the beam as shown below

Step 11)

i) Now we have to add the slabs

ii) Select Quick draw floor

iii) Draw the slabs as shown below

Step 12)

i) Now we have to assign the loads

ii) Select Define

iii) Click on load patterns

iv) Define load pattern dialogue box will open

v) Add the Following loads and Select the IS code for Seismic Case as IS -1893

iv) The direction and eccentricity were selected as the X direction

v) The Response Reduction Factor R was taken as 5

vi) Seismic zone is 5 so Z=0.36

vii) Soil type was taken as III

viii) Importance factor for residential building with less than 200 is taken 1 and time period is taken as 0.2

Step 13)

i) Now we have to assign the loads to the strucure -

1) AAC block load - 3.5 kn/m2

2) Live loads were applied to slabs next.

i) As per IS 875 in residential buildings its 2kn/m^2 for rooms and

3) Floor Finish

i) In the same way select slabs to assign floor finish which is 1 Kn/m^2

Step 14)

i) Now we have to assign Mass source

ii) For that Define menu- mass sourceoptions to open the mass source dialogue box.

iii) Now select Modify mass source data option and click OK

iv) Now mass source datawas provided as shown and load patternwas also added to it.

v) For live load upto 3Kn/m2 - we have to assumed some fraction of live load i.e 25%

Step 14)

i) Now we haev to assign diaphragm

ii) In assign menuselect Shellfollowed by Diaphragm to open the shell Assignment diaphragm dialogue box

iii) Select D1 from the diaphragm assignments and click apply followed by OK.

The Diaphragm D1 is applied and is as shown below.

Step 15)

i) Now we have to add the load combinations

ii) Click on Add default Design Combo

Step 16)

i) Now we have to create a Modal analysis

ii) For that define tab- modal cases- and select modify

iii) Enter the data’s as shown in image. Maximum number as 20.

Step 17)

i) New function was defined as per the IS 1893 for response spectrum analysis.

ii) After selecting the response spectrum the new tab is visible,

iii) In that we choose IS 1893:2016 from the "Choose function type" and click on the Modify /Show option as shown below

iv) Two load cases was defined for response spectrum analysis and set default scale factor initially

Step 18)

i) Now we have to check themodel for errors,go to Analysis tab and select check model.

Step 19)

i) Now Run the model

ii) Click on Run Analysis

'

Step 20)

1) Modal Participation ratio -

i) Modal number check for that go to Display-Show Tables-Analysis Results-Structure Output-Modal Information-Modal mass

participation ratio.

ii) According to IS 1873 clause 7.1, the natural period corresponding to fundamental torsional mode of oscillation

should not be greater than sum of two fundamental translational mode of oscillation (Tx+Ty>Txy)-from

table 0.789+0.749=1.534>0. 745. hence no torsional irregularity.

iii) IS 1873-clause 7.1, table 6 the first three modes contribution should be more than 65% of mass participation factor in each principal plan

direction. Here it is 0.71>0.65.

iv) Here Tx=0.789 and Ty=0.749, differ by 4%, hence conclude that building is irrregular in mode of oscillation in two principal plan direction.

From modal number, maximum required is 13 number as it captures more than 90% of mass in all 6 degrees of freedom.

2) Storey response plot:

ii) For this go to Display-Story Response Plot- Maximum Storey drift

iii) Here storey response for maximum storey drift is less than 0.004 for both X and Y

21) Beam Design Check

i) Click on beam design check

ii) Check for Beam Shear reinforcement

iii) Column Longitudinal Reinforcement

iv) Column Shear Reinforcement

Beam Reinforcement details

Column Reinfocement Details

Design of Foundation - Pile foundation

Step 1)

i) In order to export the ETABS model into SAFE click on file – Export – Story as SAFE V12.f2k file option

ii) Once you click on this option folowing diaog box will open

iii) Select Story as Base

iv) Now Save the file to desired location

Step 2)

Given data:-

i) Column of size:- 550mm *550 mm

ii) pile has a load carrying capacity of 280kN

iii) Pile length-16 m and dia of pile -500 mm

iv) SBC-150kN/m^2

Step 3)

i) Number of piles=Total Axial load/pile capacity=(1.5DL+1.5LL)/280= numbers

ii) Piles in the springs are defined as spring so for that the spring constant

Step 4)

i) K=EA/L

E=5000(fck)^0.5=5000(25)^0.5=25000 N/mm^2

Area of pile =22/7*d^2=3.142*(500)^2/4=196375m^2

L-10000m

K=25000*0.7855/16=306835.9N/mm==419

Spacing of the piles as per clause number 6.6.2 of IS 2911

the spacing between the piles =2.5dia of the piles =2.5*500=1250mm

Step 5)

i) We can see that all the grids are exported to the safe .

Step 6)

i) Now we have to assign the Material proprties

ii) Define - Material Properties

i) Click on Add new materials

iii) Once you click Add new material add the following parameters

iv Material Type - Concrete

v) Grade - M25

vi) Click on okay .

vii) Simialarly add the Rebar Properties

Step 6)

i) Now we have to define Slab properties

ii) In pile cap we have to define 3 slabs properties

iii) For Pile Foting

iv) For Column

v) For Pile cap

Step 7)

i) Once slab proerties are defined

ii) Now we have to start the modeling

iii) Select Quick draw slab options

Step 10)

i) Now we have to add Springs to the pile because it behaves like a spring

ii) Click on Assign – Support Data – point springs

iii) Spring Constant from above calculation is taken as

iv) Add Spring Constant 419 kn/mm

v) Select - Compression Only

Step 11)

i) Check the model

ii) And Run the analysis

1) Check for Displacement -

We found that Displacement is less than allowable settlement

i.e 0.8 < 25mm

2) Check for Punching Shear -

i) Click on Display - Punching Shear

ii) As we can see that Punching shear is less than 1

i.e 0.77 <1.....................................Safe

Step 12)

i) Now we have to add the Design srips

ii) Click on Edit - Add / Edit Design Strips

iii) Add the Strips in both X and Y direction

Step 13)

i) Run the model again

ii) Click on Display - Show slab Design

Similarly in B direction

Results -

i) G+3 hostel was designed and analysed in ETABS

ii) Foundations was designed and analysed in SAFE

All the check are done as per IS 13920-2016

i) Column Dettail Reinforcement

ii) Beam Reinforcement

3) Pile Cap Reinforcement