Foundation Design using SAFE

1. Answer:

Aim: To use SAFE to model the isolated footing, analyze it, and design it in order to confirm the dimensions, depth, and steel calculation supplied

Procedure:

Every step will be described, along with a step-by-step guide.

Step 1: Launch the safe software

Make a fresh model.

Modify the configuration

Step 2: Column dimensions are 400 mm by 400 mm.

2000 KN is the unfactored gravity load (DL+LL).

Soil's safe bearing capacity is 150 KN/m^.2.

Assume Fe 500 HYSD bars and concrete of M25 grade.

50 mm is the settlement.

FOS = 3 Sub-grade modulus = FOS*, for example. 150 * 3/0.05 = 9000 KN/m^ is the safe bearing capacity/settlement.3.

Gravity load without factoring in = 2000/1.5 = 1333.33 KN

Dead load divided by 1333.33 is 666.6 KN.

1333.33 / 2 = 666.6 KN is the live load.

Steel's yield strength is 500 N/mm^2, and its ultimate strength is 575 N/mm^.2 Footing Area = 1333.33/150 = 8.88 m^2 Footing Size = L = B = √(8.88) = 3 m

Use 4 m * 4 m for your square footage.

Step 3: Define Materials

Step 4: Add new material properity for M25 grade of concrete.

Step 5: Add new material property for Fe 500 HYSD bar.

Step 6: Define slab property.

Step 7: Assign area spring property.

Step 8: Assign load assessment loads.

Step 9: Define load combinations.

Step 10: Check the model and run the analysis.

Step 11: Check for bearing pressure under servicibilities conditions.

Step 12: Now, unlock the model, add design strips again run the analysis.

Step 13: Check the flexural reinforcement and punching shear.

Punching shear is less than 1, at 0.792 N/mm^2. It is safe as a result.

RESULTS: SAFE software was used to analyze isolated footing.

2Answer:

Aim: Using SAFE software, create, analyze, and design the pile cap. Assess the pile group, the depth of the pile cap, and the longitudinal steel calculations on the top and bottom faces in both directions.

Procedure:

Column dimensions: 600 by 600

Gravity load unfactored (DL + LL) = 1175 KN

Pile length is 16 meters.

The pile's diameter is 500 mm.

200 KN is the load carrying capacity.

Assume Fe 500 and concrete of M25 grade.

There are 1175/200 = 6 piles.

Elasticity modulus: E = 5000 * √ (fck) = 5000 * √ (25) = 5000 * 5 = 25000 N/mm^2

Piles' area is A = 3.14/4 * 500^2 = 193649.54 mm^2.

k is the spring constant; it is equal to E*A/L = 25000*193649.54/16000 = 306796.15 N/mm = 306796.15 KN/m.

1.5 * 500 = 1250 mm is the pile spacing, with 150 mm projections on either side.

pile cap length is equal to 1250+1250 + (250+150) * 2 = 3.3 m.

Pilescap width = 1250 + 2 * 400 = 2.05 m

Pile cap thickness = 2*pile diameter + 100 = 1.1 m

• Open SAFE software
• Create new Model
• Define material Property
• Define slab property
• Pile property - draw by points
• Drag it to the four points for creating pile cap
• Draw the points for creating pile caps at specified offset distance.
• Draw the column at mid point for specified offset distance.
• Draw the circular object and rectangular object at the defined points
• Assign the joints springs for pile caps
• Assign Z azis's spring constant, which was previously determined to be 30796.15 KN/m.
• Assign the joint assessment force for the column, i.e dead and live load
• Define load combinations
• Check the design concrete slab preferences as per IS 456-2000
• Check the automatic mesh option
• Check the model and run the analysis
• Maximum deflection = 4mm, hence Safe
• Check for reactions
• Reactions = 288KN
• Untick the model, and create the design strip
• Click the model and check its design for both column strip
• Run the analysis
• Check for flexural reinforcement
• Check for Punching Shear
• Hence it is safe in permisible limits

RESULTS: SAFE software was used to analyze the pile foundation.