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

INTRODUCTIONS:-

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:-

• in the first step 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 and select the indian codes and click ok.
• Click on the custom grid data and click ok.
• Now the values as per the given plans are inserted  and our model will be ready.
• In the next step material has to be defined. Go to define and click on material properties and add the concrete and rebar material specification.
• In the next step section properties has to be defined. Go to define and click on section properties and add the beam and column specification.
• 450 mm x 600 mm beam size is provided for the all the beams.
• 450 mm x 600 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.
• In the next step define the slab properties by going in to define and 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)
• Draw all the beams using beam command.
• Draw all the columns using column command
• In the next step slabs are drawn using slabs command
• Now we have to decide the location of shear walls and how much should 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.
• 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.

• The live loads values are got from Is 1875 part 2 for residential buildings.
• As per table 1 of IS 875 part 2 For hostel buildings
• 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
• Since the building.
• Time period is calculated as per clause number 7.6.2 of IS 1893
• Now define the load combinations
• In the next step we have to define the mass source, for that go to define 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.
• And select all the floors and apply diaphragm D1
• 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.
• now go to define function and click on response spectrum and 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.
• now go to define Load cases and 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 U 2 for Rsy and IS function
• Go to define click on load combinations and click on default design combo,click on create frame design and click on convert to design combo click ok.
• Now check the model if there are any warning correct it and run the model.

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

RESULT AND DISCUSSION:

• Go to display then click show tables and then structural data click ok.
• Click on show tables , select the Analysis results structure output click ok.
• 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.
• 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%.
• Go to concrete frame design and select the start design or check . and note down the va;ues of reinforcement details.
• 2.select modal participating ratios we have got that at mode 7 we have got above 90% so its ok.
• 3.now select the base reactions check that Eqx Eqy   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.

• 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.

Given  data:-

Column of size:- 450mm *600 mm  & 600mm*450m m

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 beam 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 have go 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