Project 2_Design & Analysis of a Hostel building at Guwahati, Assam
AIM - To carry out modelling, analysis, design and preparation of structural drawings of G+3 RCC building at Guwahati Assam.
Introduction -
1) ETABS is an engineering software product that provides analysis and design of multi-story buildings.
2) SAFE represents the state of the art in three-dimensional finite element technologies for civil engineering.
3) Here in this project we are doing design analysis of G+3 building located in Guwahati,
Assam using ETABS software and then foundation design is done using SAFE software
PROCEDURE -
Step 1)
i) Open the Etabs software icon from the desktop
ii) Once the software is open - Click on New Model
Step 2)
i) Once you click on New Model
ii) Model Initialization settings 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 OK
ii) The following grid setup dialog will open
ii) In the New Model Quick Templates, under Grid Dimensions, select a custom grid spacing
iii) Once you click on Custom Grid Spacing
iv) Click on Show grid data as spaces
v) Now enter the floor details
vi) As stated in the question and story 1 was chosen as the main story
vii) Click OK.
Step 5)
i) Once you click OK
ii) A floor plan and a 3D view of the model are created in the model space
Step 6)
i) Now we need to define the properties of the material
ii) Click on Define
iii) Click on Material Properties
v) Add new material like concrete
vi) Select the quality of concrete - ..............................
vii) Standard as Indian
viii) Click on OK.
ix) Remaining data is as per IS code
Step 7)
i) Similarly, we need to define material properties for steel
ii) Click on Define
iii) Click on Material Properties
iv) Select New Material as Reinforcement
v) Select steel grade - HYHD - Fe415 grade...................... (specified)
vi) Standard as Indian
vii) Click on OK.
viii) Remaining data is as per IS code
xi) Material properties are added
Step 8)
i) Now we need to define the section properties ( Column and Beam )
ii) Click on Define
iii) Select - Section Properties
iv) Click on Frame Sections
v) Click OK.
vi) Click on Add New Property
vii) Select Rectangle shape
viii) Enter property name - Beam 400x500............(given)
ix) Material type - M25
x) Section shape – rectangular concrete
Depth - 500 mm Width - 400 mm
xi) Click on Edit / View Reinforcement
xii) Select only design M3 (beam)
xiii) Select reinforcement materials like HYHD Fe415 in both directions
xiv) Click OK.
xv) Similarly, we have to do the same as for the column.
xvi) Property Name - Column 550 x 550 mm
xvii) Material - M25
xviii) Depth - 550 mm
xix) Width - 550 mm
xx) Click Edit / View Reinforcement
xxi) Select only design M3 (column)
xxii) Select reinforcement materials like HYHD Fe415 in both directions
xxiii) Click OK.
Step 9)
i) Now we need to define the board properties
ii) Click on Define
iii) Select Section Properties - Select Plate Properties
iv) Click on Board Sections
v) Enter property name - Plate 150
vi) Plate material - M30
vii) Modeling type - Membrane
viii) Type - Plate
ix) Thickness - 150 mm
Step 10)
i) We are now left with a 3D view to see the properties
ii) Now we need to add the columns and beams
iii) Click on Quick Draw Column option
iv) Select the column properties we defined earlier
v) Draw the columns in the grid as shown below
vi) Note that - The All Stories option which is at the bottom should be selected
vii) Similarly we also have to draw rays
viii) Select the Quick Draw Beam option
ix) Select the beam properties we defined earlier
x) Draw a ray
Step 11)
i) Now we need to add the boards
ii) Select a quick draw floor
iii) Draw the plates
Step 12)
i) Now we have to assign the load
ii) Select the Define option
iii) Click on load patterns
iv) The Define Load Pattern dialog will open
v) Add the following loads and select IS code for seismic case as IS -1893
iv) Direction and eccentricity were selected as X direction
v) Response reduction factor R was taken as 5
vi) Seismic zone is 5 so Z=0.36
vii) The soil type was taken as III
viii) Importance factor for residential building less than 200 is taken as 1 and time period is taken as 0.2
Step 13)
i) Now we need to assign loads to the structure -
1) AAC block load - 3.5 kn/m2
2) Further, payloads were applied to the plates.
i) As per IS 875 in residential buildings its 2 kn/m^2 for rooms and
3) Surface treatment of the floor
i) In the same way, select the boards to which you will assign the floor finish, which is 1 Kn/m^2
Step 14)
i) Now we have to assign the Mass source
ii) To do this, the Define Menu - Bulk Source Options to open the Bulk Source dialog box.
iii) Now select Edit Bulk Source Data and click OK
iv) The bulk source data as shown has now been provided and the load pattern has also been added to it.
v) For live load up to 3Kn/m2 - we have to assume a certain part of the live load, i.e. 25%
Step 14)
i) Now we need to assign the diaphragm
ii) From the assignment menu, select Shell followed by Diaphragm to open the Diaphragm Shell Assignment dialog box
iii) Select D1 from the diaphragm assignment and click apply and then OK.
Diaphragm D1 is used and is shown below.
Step 15)
i) Now we need to add load combinations
ii) Click on Add default Design Combo
Step 16)
i) Now we need to create a modal analysis
ii) For this define tab-modal cases- and select edit
iii) Enter the data as shown in the figure. The maximum number is 20.
Step 17)
i) A new function has been defined as per IS 1893 for response spectrum analysis.
ii) After selecting the response spectrum, a new tab will appear,
iii) In that we select IS 1893:2016 from "Select Feature Type" and click on Edit/View option as shown
iv) Two load cases were defined for response spectrum analysis and a default scale factor was set initially
Step 18)
i) Now we need to check the model for errors, go to the Analysis tab and select check model.
Step 19)
i) Now run the model
ii) Click Start Analysis
Step 20)
1) Modal participation ratio -
i) Check modal number for this go to View-View Tables-Analysis Results-Structure Output-Modal Information-Modal Mass participation ratio.
ii) According to IS 1873, Clause 7.1, the natural period corresponding to the fundamental torsional mode of oscillation it should not be greater than the sum of the two basic translational modes of oscillation (Tx+Ty>Txy)-od
table 0.789+0.749=1.534>0. 745. so no torsional irregularity.
iii) IS 1873-Clause 7.1, Table 6, contribution of first three modes should be more than 65% of mass participation factor in each master plan
direction. Here, 0.71>0.65.
iv) Here Tx=0.789 and Ty=0.749 differ by 4% so it is concluded that the building is irregular in oscillation mode in the two main plan directions.
Of the modal number, the maximum desired number is 13, as it captures more than 90% of the mass in all 6 degrees of freedom.
2) Floor response graph:
ii) For this go to Display-Story Response Plot- Maximum patro drift
iii) Here the floor response for maximum floor displacement is less than 0.004 for both X and Y
21) Beam design check
i) Click on beam design check
ii) Check the shear reinforcement of the beam
iii) Longitudinal column reinforcement
iv) Column shear reinforcement
Beam reinforcement details
Column reinforcement details
Foundation design - Pile foundations
Step 1)
i) To export the ETABS model to SAFE, click on the file – Export – Story as SAFE V12.f2k file option
ii) After clicking on this option, the following dialog will open
iii) Select Story as the base
iv) Now save the file to your desired location
Step 2)
Data given:-
i) Column size:- 550 mm * 550 mm
ii) the pile has a load capacity of 280 kN
iii) Hair length-16 and hair diameter -500 mm
iv) SBC-150 kN/m^2
Step 3)
i) Number of piles=Total axial load/pile capacity=(1.5DL+1.5LL)/280= numbers
ii) Piles in springs are defined as springs, so the spring constant
Step 4)
i) K=EA/L
E=5000(fck)^0.5=5000(25)^0.5=
Area of pile =22/7*d^2=3.142*(500)^2/4=
L-10000m
K=25000*0.7855/16=306835.9N/
Pile spacing as per clause 6.6.2 of IS 2911
distance between piles = 2.5 pile diameter = 2.5*500=1250mm
Step 5)
i) We can see that all grids are exported to the vault.
Step 6)
i) Now we need to assign the Material properties
ii) Define - Material properties
i) Click on Add New Materials
iii) Once you click on Add New Material, add the following parameters
iv Type of material – Concrete
v) Grade - M25
vi) Click on OK.
vii) Similarly add reinforcement properties
Step 6)
i) Now we need to define the board properties
ii) In the pile cover we need to define 3 slab properties
iii) For Pile footing
iv) For a column
v) For pile cap
Step 7)
i) Once the board properties are defined
ii) Now we need to start modeling
iii) Select Quick Plate Drawing Options
Step 8)
i) Now we need to add Springs to the stack because it behaves like a spring
ii) Click on Assign – Support Data – Point Springs
iii) The spring constant from the above calculation is taken as
iv) Add spring constant 419 kn/mm
v) Select - Compression only
Step 9)
i) Check the model
ii) Run the analysis
1) Check displacement -
We found that the displacement is less than the allowed settlement
i.e. 0.8 < 25 mm
2) Check for punching -
i) Click on Display - Punching Shear
ii) As we can see the punching shear is less than 1
i.e. 0.77 <1............................
Step 10)
i) Now we need to add srips Design
ii) Click on Edit - Add / Edit Design Bars
iii) Add strips in both X and Y direction
Step 11)
i) Run the model again
ii) Click on View - View board design
Similarly in direction B
Result -
i) The G+3 dormitory was designed and analyzed in ETABS
ii) Foundations were designed and analyzed in SAFE
All inspections are done as per IS 13920-2016
i) Reinforcement of column details
ii) Beam reinforcement
3) Reinforcement of the pile cap
