Week 12 Challenge
Design of Foundation in STAAD Foundation
Q1. Isolated Footing
Design isolated footing for a column 300 mm x 450 mm, carrying axial load of 1500 kN and Mu = 150 kNm using STAAD. Foundation. Assume that the moment is reversible. The safe bearing capacity of the soil is 200 kN/m2 at a depth of 1 metre from ground level. Use M 25 and Fe 415 for the footing. Also validate the design through hand calculation.
Ans:
Aim: To design Isolated footing design using STAAD foundation for the given data
Size of column :30033*450mm
Axial load=1500KN
Moment Mu=150KNm
SBC of soil = 200KN/M^2 at a depth of 1m from GL
Grade of concrete =M25
Grade of steel =Fe
Procedure:
Step 1: Open staad foundation and click on general design to start the design of combined footing
Step 2:New window will appear,enter the support coocrdinates for the isolated footing.Let it be at the origin
Step 3:Go to column position and enter rge coordinates as (0,0,0)
Step 4: Set the column dimensions as 300mm *450mm .
Step5:Go to loads and factors option and create new load option to create new cases for DL and LL also add load condition of Fy =-1500KN and Mx=150KNM
Step 6: Create the load combination cases ad per Indian standard codes .
Step 7: Create the job info to analyse and design the footing
Step 8: New job has been create for the isolated footing
Step 9: Fill the data for the design of the footing
SBC of soil = 200KN/M^2 at a depth of 1m from GL
Grade of concrete =M25
Grade of steel =Fe
Step 10: After entering the data click on design option to analyze and design the footing
Step 11: Click yes to start the design process
Design has been done successfully
Result :
Dimnsion of footing =3m X3m
Overall depth of footing,D = 650mm
Depth of footing is checked for BM,Single ,double shear and found safe.
No tension steel is needed
Development length =648mm
Q2. Combined Footing
Design a combined footing using STAAD. Foundation for two columns C1, 400 mm x 400 mm carrying a service load of 800 kN and C2, 300 mm x 500 mm carrying a service load of 1200 kN. The column C1 is flushed with the property line. The columns are at 3.0 m c/c distance. The safe bearing capacity of soil is 200 kN/m2 at a depth of 1.5 m below the ground level. Use M 20 and Fe 415 for columns and footing.
Ans:
Aim:To design a combined footing for the given data
Procedure:
Step 1: Open the staad foundation and click on general mode and enter the support coordinates to add the columns.Columns C1 and C2 placed at a distance of 3m and their dimensions are 400mm X 400mm & 300mm X500mm
Step 2: Assign load of 800KN on C1 and 1200Kn on C2
Step 3: Generate load combinations
Step 4: Create the job setup .Design code should be indian and units in SI unit
Step 5: Edit current job under job setup then create strip footing after selecting both the columns
Under combined footing job we have to assign
Unit weight of concrete
Maximum and minimum spacing of bar.
Strength of concrete = M20
Yield strength of steel=415N/mm^2
Min and max bar size
Clear cover of pedestal and footing
Unit weight and SBC of soil
Depth of soil above footing
Min % of contact area of service load.
Footing geometry such as overhang length,min width ,max length,max-min thickness and thickness increment
Result :
Design is successful with footing dimension as 9.2mX7.5m and thickness 0.5m
C-1 column is flushed with property line that is left over hang is 0
Main steel top 8mm dia @50mm c/c
Main steel bottom 8mm dia @55mm c/c
Secondary steel bottom 12mm dia 60mm c/cand top 8mm dia 8033 c/c
Design is safe aganist sliding,single shear,punching shear,soil pressure,overturning
Design has been done successfully.