Week 12 Challenge

1. 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.

SOLUTION:

• Go to STAAD foundation.
• select the general foundation mode.
• enter the job setup by clicking "Job setup " at left bottom corner & select ispolated footing.

• By clicking Foundation plan one can define the grid of foundation

• Go to home click to add support in order to add the footing position or you can go "Column Position" for positioning of footings.

• After positioning the column we have to give the dimension of the footing.
• By clicking to "Column Dimension" we can define the dimensions of the footing accordingly.

• We can also add pedestals by clicking to "Pedestal And Anchor Bolt".
• After clicking we can define the Height, Width & length of pedestal.

• After creating all the geometry we can add load cases & intensity.
• Go to "Load & Factors ", click to "Create new load case" to add the load cases.
• click to " Add Column Reaction Load " to add the load intensity.
• After adding the intensity go to "Create load combination" and add the service & ultimate load combination.

• After adding the load combination add all the design parameters & run the analysis.

• Validation of design through hand calculation.

2. 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.

SOLUTION:

• Go to STAAD foundation.
• select the general foundation mode.
• Locate the foundation position as per the given data.

• Once the loacation of foundation is fixed we have to give the dimension of the pedestals.

• After creating all the geometry we can add load cases & intensity.
• Go to "Load & Factors ", click to "Create new load case" to add the load cases.
• click to " Add Column Reaction Load " to add the load intensity.
• After adding the intensity go to "Create load combination" and add the service & ultimate load combination.

• Analyse the foundation for the result.

• RESULT: It is concluded that-

  • Design is successful with footing dimension as 9.2m x 7.5 m and thickness 0.5 m.
  • C-1 column is flushed with property line that is left over hang is 0.
  • Main steel top 8mm dia bar @ 50 mm c/c
  • Main steel bottom 8 mm dia bar @ 55 mm c/c
  • Secondory steel bottom 12 mm dia 60 mm c/c and top 8 mm dia 80 mm c/c
  • Design is safe against sliding , single shear , punching shear, soil pressure, overturning.

  Hence, design of Combined Footing has been done succesfully.