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.
square footing for a column size of 400x400
compression axial load for the load combination of (1.5 DL + 1.5 LL) is 2000 KN
mine sate soil bearing capacity is 150 KN/m2 at a depth of 2 metres below E.G.L
Assume M25 concrete grade.
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
Data required for SAFE analysis & Design
Unfactored load = 1175 kN
Dead load breakup = 1175/2 = 587.5 kN
Live load breakup = 1175/2 = 587.5 kN
Point spring of Pile = AxE / L = 196349 × 25000 / 16000 = 306796 kN/m
k for SAFE analysis = 306.8 kN/mm
Rebar yield strength (Fy) = 500 N/mm2
Rebar ultimate strength (Fu) = Say 575 N/mm2
Elastic modulus of M25 concrete = 25000 N/mm2
Data required for SAFE analysis & Design
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 x pile diameter (500 mm)
Assumed pile cap depth = 500 mm
