Foundation Design using SAFE

1. Model the isolated footing provided in week 11 challenge on SAFE. Analyze and design it to verify the size, depth and steel provided as per calculations.

Ans:-

As per week 11 challange

• Size of column 400x400mm
• Compression load combination (1.5DL+1.5LL) is 2000kn
• SBC150kn/m2 at a dpth of 2m
• Grade of concrete M25

Data required for SAFE Analysis

• Un factored load 2000/1.5=1333.3Kn
• Assume Dead and Live load 1333.3/2=666.7KN
• Subgrade modulus for soil=FOSxSBC/ maximum settlement

=3x150/0.05

=9000kn/m3

• Fy=500n/mm2
• Fu=575n/mm2
• E=25000 n/mm2

result:

1. SBC under service load....safe

2 settelment under survice load

3 Two way shear check

4 R/F detail

2. A column of size 600x600 carrying an unfactored gravity load (DL+LL) of 1175 KN is to be supported on pile cap, which ultimately transfers load to the piles underneath. Piles of 16 metres length and 500 mm diameter are to be used. Each pile has a load carrying capacity of 200 KN. Model, analyse and design the pile cap on SAFE to evaluate the following:

• Pile group to be used
• Depth of pile cap
• Longitudinal steel on top and bottom face in both directions

Note: Participants must refer to IS 2911 (part 2) and SP 34 for 2nd challenge

Ans:-

Data

• Un factored load – 1175kn
• Dead and Live Load -587.5KN
• Point spring of pile –

=EA/L

=25000x196349/16000

=306796kn/m

=306.8kn/mm

• Fy- 500n/mm2
• Fu-575n/mm2
• E-25000n/mm2

Data for safe analysis

• Number of pile required – 1175x1.1/200

-6.5

Consider 8 pile

• Take centre to centre distance between pile -3 xpile dia

-3x500=1500

• Edge of pile distance =500 from pile center
• Assume pile cap depth=500mm

Result:

1-indivisual pile capacity

2-sttelment under service load

3- Two way shear check

4- footing design