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

In this project, participants will get to experience the entire design process from modeling, analysis, design, and preparation of construction drawings. The architectural drawings of a G+3 RCC building are 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 rest on type 3 soil. Piles of length 10 meters and 500 mm diameter with a load-carrying capacity of 280 KN are to be used. 

The ground floor level will be at a height of 2 meters above the existing site level to prevent floodwater 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 the ground floor

AIM:

Create and Analyse the given building in ETABS 2018, the structural model has to be prepared by IS 1893 and as per IS 13920. To design the pile cap and pile reinforcement details, Tie the beam connecting the pile caps, and sketch the column reinforcements, to produce the framing plan and beam detailing for the ground floor.

Given data:-

The walls are made of AAC blocks Pile capacity -280kN, M25 Concrete Fe 500 steel, Soil type 3.

INTRODUCTIONS:-

1. Etabs is the software that is being used to create a structural model of a 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 to  design the foundations

PROCEDURE:-

1. in the first step open the tabs software go to file and click on the new model.
2. A model initialization window will appear.
3. Click on the use built-in setting select the Indian codes and click ok.
4. Click on the custom grid data and click ok.
5. Now the values as per the given plans are inserted and our model will be ready.
6. In the next step material has to be defined. Go to define and click on material properties and add the concrete and rebar material specifications.
7. In the next step section properties have to be defined. Go to define click on section properties and add the beam and column specification.
8. A 450 mm x 600 mm beam size is provided for all the beams.
9. 450 mm x 600 mm beams are provided for the beams at the periphery to increase the torsional resistance of the building
10. The moment of inertia for beams and columns should be reduced by 0.35% and 0.4% respectively.
11. 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 Staircase it should be  One way.
12. Define the staircase slab and provide its thickness as 175 mm( varies from 175-225mm)
13. Draw all the beams using the beam command.
14. Draw all the columns using the column command
15. In the next step slabs are drawn using the slabs command
16. Now we have to decide the location of the shear walls and how much should be the length of the shear wall.
17. As per Indian standards the length of the wall should be  5-2% in each direction.
18. The thickness of the shear wall is assumed to be 250 mm.
20. Now go to define and define the loads.
21. Next select the beams and floors and add the loads.

22. AAC load of 3.5 kN/m since the AAC blocks are used.
23. The live load values are obtained from Is 1875 part 2 for residential buildings.

24. As per table 1 of IS 875 part 2

25. For hostel buildings

27. As per clause number 875 part 2 reduction factor should be applied to the imposed loads.
28. Live load at the roof floor needs to be reduced hence 2 kN/m is applied.
29. Floor finish on all the floors 2 kN/m  is applied.
30. Seismic loads should be defined so as per IS 1893 Table no. 8 importance factor should be 1.2
31. Since the building.
32. Period is calculated as per clause number 7.6.2 of IS 1893

T=0.09h/sqrt

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

33. Now define the load combinations
34. In the next step we have to define the mass source, for that go to define and click on the mass source add on the new, and 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.
35. And select all the floors and apply diaphragm D1
36. In the next step we have to define 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.
37. now go to define the function and click on response spectrum and add a new function by IS 1893-2016 check all the values click ok.
38. Name the function as IS function, Response spectrum IS function IS 1893-2016 tab will appear to check all the values Seismic zone factor soil type, importance factor click on linear x linear y click ok.
39. now go to define Load cases and click on Add new case and Add RSX and Rsy
40. select the response spectrum click on Add select the function as IS function and U1 for Rx, U 2 for Rsy, and IS function
41. Go to define click on load combinations click on default design combo, click on create frame design, click on convert to design combo click ok.
42. Now check the model if there are any warnings correct it and run the model.

Results  and discussion

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 values 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 ratio and check the values for U1 U2 U3 some of these UX Uy UZ for the first 3 modes should be greater than 65%.
5. 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 it's okay.

3. now select the base reactions and check that Eqx Eqy values should be the same and Rsx and Rsy values also should be at least equal to Eqx and Eqy respectively. if not then just take the rsx values and divide them by Eq values whatever the values will get those values need to be multiplied in the load cases rsx tab.

4. 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 them by the Total base shear which should be greater than 90%. If now add the shear walls in the appropriate directions