Foundation Design using SAFE

 1 

   Aim 

           To create isolated footing provided in on SAFE. Analyze and design it to verify the size, depth and steel provided as per calculations.

 Introduction 

           To calculate the value and then to create the isolated footing in the SAFE and then to analysis the structure 

Square footing for a coloumn size of 400*400 

Compression axial load for the load combination of(1.5 DL + 1.5 LL) is 2000 kN 

The safe soil bearing capacity is 150 kN/m^2 at a depth of 2 m below E.G.L 

Assume M25 Concrete grade 

Unfactored load = 2000/1.5 = 1333.3 kN 

Dead load breakup = 1333.3/2 = 666.7 kN

Live load breakup = 1333.3/2 = 666.7 kN

Subgrade modulus for soil = Safe bearing capacity * Factor to Ultimate / Maximum settlement 

                                      = 150*3/0.05 = k = 9000 kN/m^3 

Rebar yield strength Fy = 500 N/mm^2 

Rebar Ultimate strength Fu = 575 N/mm^2 

Elastic modulus of M25 concrete = 25000 N/mm^2 

            

2

    Unfactored load = 1175 kN 

   Dead load breakup = 1175/2 = 587.5 kN 

  Live load breakup = 1175/2 = 587.5 kN 

Point spring of pile = A*E/L = 196349*25000/16000 = 306796 kN/m 

k for SAFE analysis = 306.8 kN/mm

Rebar yield strength (Fy)= 500 N/mm^2 

Rebar ultimate strength (Fu)= 575 kN/mm^2 

Elastic modulus of M25 concrete = 25000 N/mm^2 

Number of piles required = Unfactored load with self weight addition / individual pile capacity 

= 1175*1.1/200 = 6.5

Consider 8 piles for symmetric placement of piles under pile cap

Take center to center distance between piles = 3 * pile diameter (1500 mm)

Edge distance from pile center = 1 * pile diameter (500 mm)

Assumed pile cap depth = 500 mm