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

QUESTION: In this project, participants will get to experience the entire design process from modelling, analysis, design and preparation of construction drawings. The architectural drawings of a G+3 RCC building is provided. The following information on the building is to be used:

. Location – Guwahati, Assam

. Function – Hostel block in an academic institute

The walls will be made of AAC blocks. Other loadings are to be calculated as per the architectural drawings. 

The buildings rests on type 3 soil. Piles of length 10 meters and 500 mm diameter with load carrying capacity of 280 KN is to be used. 

The ground floor level will be at a height of 2 meters above existing site level to avoid flood water enter the building.

M25 grade of concrete with Fe500 for longitudinal reinforcement and Fe 415 for shear reinforcement is to be used. 

The following design IS codes will be required for reference:

. IS 875 part 1

. IS 875 part 2

. IS 13920

. IS 1893

. IS 2911 part 2

. IS 456

. SP 34

Students will have to produce the following:

. Etabs model for the two blocks on either side of the expansion gap

. Foundation details illustrating the pile & pile cap reinforcement

. Tie beam details connecting the pile caps

. Column reinforcement

. Framing plan for typical floor

. Beam reinforcements for ground floor

ANS:

AIM: To model, analysis, design and prepar the construction drawings from the provided architectural drawings of a G+3 RCC building. To design Foundation details illustrating the pile & pile cap reinforcement, Tie beam details connecting the pile caps, Column reinforcement, Framing plan for typical floor, Beam reinforcements for ground floor

INTRODUCTION:

1. Etabs is the software which is being used to create a structural model of given building.

2. In the first step note down the values of grid spacing from the given structural plans.

3. Next Create the Structural model and run the Model

4. Analyse the result and note down the result values from ETABS.

5. Next is to export the model to SAFE 2016 software in order to design the foundations

PROCEDURE:

STEP: 1 First open the etabs software

. go to file and click on new model.

. Model initialisation window will be appeared.

. Click on the use built in setting < select the indian codes < click ok.

. Click on the custom story data < click ok.

. Click on the custom grid data < click ok.

. Now the values as per the given plans are inserted and our model will be ready.

STEP: 2

. In the next step material  has to be defined.

. Go to define and click on < material properties

. add the concrete

. rebar material specification 

STEP: 3 Define section properties:

.  Go to define < click on section properties < add the beam and column specification.

. 450 mm x 600 mm column size is provided for the all the column.

. 230 mm x 300 mm beams are provided for the beams at periphery so as to increase the torsional resistance of the building

. Moment of inertia for beams and columns should be reduced by 0.35% and 0.4% respectively.

 

STEP: 4 In the next step define the slab properties

. Go to define < slab sections.

. Add the slab property as While defining the slab for Stair case it should be One way.

. Define the stair case slab and provide its thickness as 175 mm( varies from 175-225mm)

 

 

STEP: 5 . Draw all the beams using beam command.

. Draw all the columns using column command

. In the next step slabs are drawn using slabs command

STEP: 6 . Now we have to decide the location of shear walls and how mu = be the length of the shear wall.

. As per Indian standards the length of the wall should be 5-2% in each direction.

. The thickness of shear wall is assumed to be 250 mm.

STEP: 7

. Now go to define and define the loads.

. Next select the beams and floors and add the loads.

. AAC load of 3.5 kN/m since the aac blocks are used.

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STEP: 8 The live loads values are got from is IS 875 part 2 for residential building 

. As per table 1 of IS 875 part 2

. For hostel buildings

. Living Rooms Bedrooms and dormitories = 2 kN/m^2

. Kitchen and Laundries = 3 kN/m^2

. Billiards and public lounges  = 3 kN/m 2

. Store rooms = 5 kN/m^2

. Dining rooms,cafeterias and restaurant = 4 kN/m^2

. Office rooms = 2.5 kN/m 2

. Bath and toilets = 2 kN/m^2

. Corridors, passages, staircase = 3 kN/m^2

. Balconies = 4 kN/m^2

STEP: 9 As per clause number is 875 part2 reduction factor should be applied on the imposed loads. Live load at the roof floor needs to be reduced hence 2 kN/m is applied. Floor finish on all the floors 2 kN/m is applied. Seismic loads should be define so as per IS 1893 Table no. 8 importance factor should be 1.2 31. Since the building.

 

STEP: 10 Time period is calculated as per clause number 7.6.2 of IS 1893

T=0.09h/sqrtd

Tx=(0.09*16.85)/(67.7)^0.5-0.184 Seconds. Or Ty=0.09*16.85/(13.3)^0.5-0.415 sec

STEP: 11 Now define the load combinations

  

STEP: 12. In the next step we have to define the mass source,

. go to defin and

. click on mass source and

. add on the new,

. click on specified load data,

. in the mass options click on include lateral mass and lump lateral mass at story levels,

. in the load pattern add multiplier 0.25 for LL and 1 for all the dead and super dead loads.

 

STEP: 13 And select all the floors and apply diaphragm D1 

 

STEP: 14

. In the next step we have to define for the modal cases for that go to define and

. click on modal cases

. click add new model cases

. select eigen and put the number of modes shape required.

  

STEP: 15 . now go to define function 

. click on response spectrum

. add anew function in accordance with IS 1893-2016 check all the values click ok.

. Name the function as IS function, Response spectrum IS function IS 1893-2016 tab will appear

. check all the values Seismic zone factor soil type,importance factor click on linear x linear y click ok.

 

STEP: 16 . now go to define Load cases

. click on Add new case and

. Add RSX and Rsy.

. select the response spectrum

. click on Add select the function as IS function and U1 for Rx, and U2 for Rsy and IS function

STEP: 17 . Go to define click on load combinations and

. click on default design combo,

. click on create frame design 

. click on convert to design combo

 click ok.

 

STEP: 18 Now check the model if there are any warning correct it and run the model.

 

RESULT:

1. Go to display then click show tables and then structural data click ok.

2. Click on show tables, select the Analysis results structure output click ok.

3. Select the base reaction and check the eqx eqy vales, Rx and Ry value see which values are larger if the rX RY values are lesser than the Eqx Eqy unlock the model and then go to define load case and delete the Rx RY cases and again select the load combinations and define that again.

4. Go to modal mass participation ration and check the values for U1 U2 U3 values sume of these UX Uy UZ for the first 3 modes it should be greater than 65%.

5. Go to concrete frame design and select the start design or check. and note down the vaues of reinforcement details.

6.select modal participating ratios we have got that at mode 7 we have got above 90% so its ok.

7.now select the base reactions check that Eqx Egy values should be same and Rsx and Rsy values also should be atleast equal to Eqx and Eqy respectively. if not then just take the rsx values and divide it by Eq values whatever the values will get that values needs to be multiplied in the load cases rsx tab.

8. check for the share of shear walls go to base level and click on reaction Ex and Ey values will be available take these values and divide it be Total base shear which should be greater than 90%. If now add the shear walls in appropriate directions

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Importing the software Safe 2016

1. Go to file click on export and select the safe v12.fk.

2. A tab will appear then click on the story as base and select the loads and loads from above click on the combination click ok.

3. Goto SAFE 2016 and fo to file click import and select the file and save the file as FDB.

4. Go to dispay click on the show loads select dead above and love above the values will be appeared.

5. Given data: Column of size:- 450mm *600 mm & 600mm*450mm pile has a load carrying capacity of 280kN Pile length-16 m and dia of pile -500 mm SBC-150kN/m^2

Solution: 1. Number of piles-Total Axial load/pile capacity-(1.5DL-1.5LL)/280 numbers

2. Piles in the springs are defined as spring so for that the spring constant

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.

3. 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

4. Now in the next step we have to define the material properties for go to define and define the material properties of Concrete and Reinforcement properties Fe500 & Fe 415.

5. Select the values.

6. Go to define section properties and define pile caps .pile Dia, and column

7. Add new, defined pile cap pile 500 as Mat, and Column as Stiff.

8. Click on the quick draw around the plots a window will open there insert the columns sizes and these columns to their specified positions. Columns should be stated as stiff material.

9. In the next step pile caps needs to be drawn for that go to Quick draw slab command select pile caps and add it. Piles and pile cap should be stated as stiff material.

10. Select the pile caps and changed the rebar material as Fe 500.

11. Next go to draw and draw point and a window will open up there draw the points where piles are to be drawn.

12. Now again select the quick dfaw around the pints there select the property circular slab add piles dia in this case 0.5m and add to the points. Select these piles and again check for the rebar materials.

13. Now we have to define all the piles as spring for that go to define

14. select soil spring properties add new property there click on compression only and add the calculation value of K-EA?L.

15. Select all the piles and go to assign and select support data and select spring properties and assign it.

16. Go to define and select the define bear and define the tie beams whose thickness should be as of pile caps.

17. Check weather the rebar material is Fe 500 under design preferences

18. Go to define and define the load combinations sls and uls

19. Go to design and design preferences

20. Save the model and run the Analysis

21. Deformed shapes showed that deformations are negligible

22. Assign add the design strips

23. Run the analysis

24. Deformed shape all the values are less than 25 mm hence ok.

25. Now go to display and click on the punching shear the values we are less than 1 hence ok.

26. Now go to display and select slab design.

27. All the reinforcement details will be available

28. For X DIRECTION MIDDLE STRIP maximum Reinforcement was

. For Top:- 29834 mm^2/m=29834/3.3-9041 mm^2-28 nos. 20 mm dia are provided

. For Bottom-13326mm^2/m-4038 mm^2-13 nos. 20 mm dia are provided

29. For layer Y direction maximum Reinforcement was

. For Top:-19926-3831mm^2/m-12 nos of 20 mm dia are provided

. For Bottom-22784mm^2/m-4398 mm^2-14 nos 20 mm dia are provided