Challenge

Foundation Design using SAFE

BBaseer Ahmad1 Jan 2023

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.

AIM:-

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.

Procedure:-

Subgrade modulus:

= F.O.S X S.B.C / Settlement

where, FOS for soil is = 3

S.B.C = 150KN/m.sq
Settlement for isolated footing = 0.05mm.
Hence, subgrade modulus = 9000kn/m.sq
The compression axial load for the load combination (1.5DL + 1.5LL) is 2000KN
Unfactored load = 2000/1.5= 1333.6kN
Live load = 1333.3/2 = 666.7kN
Dead load = 1333.3/2= 666.7kN
Footing thickness = 600mm
Column load size = 400x400 mm
Grade of concrete = M25

Open the Safe application.
Click on the new modal.
Then select the units and design the codes.

Now select the single Footing .

After that now click on the define option and then click material properties.

Then click on add new material properties. Then add M25 concrete material and Fe500 rebar material.

Again click on the define option then click on section properties and then select the slab section.
When slab section is open then click on add new properties and then add Mat1 and Stiff1.

Next we have to click on quick draw slab option and assign the Mat1 properties.
Again click on the quick draw slab option and assign Stiff1 properties.

Then click on add strip design.

Next go to the define option the click on area spring property data and assign it to the central point.

Then go to the Load combination then add load.

Then click on design option then select design combination and assign the load combination to ultimate limit state.

Next go to the analyze option select automatic mesh setting do a mesh check and set it to 0.1m before running the analysis.

And then run the analysis.

Results:

Check for settlement. Hence all settlements are under satisfactory limit.

Check for soil pressure. Click to display support reaction. Hence, all support reactions are within safe bearing capacity.

Check for two way shear or punching shear which should be less than 1.

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

AIM :

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

Procedure:

Axial load = 1175KN
Length of piles 16m
Diameter of pile = 500mm
Pile capacity = 200KN
No of piles = 1175/200 = 5.875 = Assume 8 piles.

Assume grade of concrete is M25

Area of each pile: = π/4 (d^2) = π/4 (500^2). = 196349.5mm2
E = 5000√fck = 25000
Spring constant (k) = EA/L = (25000 x 196349.5)/16000 = 306796.09 N/mm = 306796.09 Kn/m

Take center to center distance between piles= 3 X Pile diameter(500mm) = 1500mm, edge spacing = 500mm
Assume pile cap depth = 1000mm
Length = 4000m and Width = 4000mm

Open the Safe application.
Click on the new modal.
Then select the units and design the codes.

After that now click on the define option and then click material properties.
Then click on add new material properties. Then add M25 concrete material and HYSD500 rebar material.

Again click on the define option then click on section properties and then select the slab section.
When slab section is open then click on add new properties and then add Stiff1, Pile1 and Slab1.