Foundation Design using SAFE

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

Introduction:

• CSI SAFE (Slab Analysis by the Finite Element Method) is the best tool for designing concrete slabs and foundations.
• SAFE provide easiness to engineer towards the safe design of structures with powerful tools like draw, analyze, design and detailing etc.
• Laying out models is quick and efficient way with the user-friendly drawing tools, or user can import model layouts from AutoCAD or loading conditions from other software's like CSI ETABS and CSI SAP2000.

Procedure:

• Open the SAFE software.
• Click on New model to create.

• New dialogue box will open and name the model Initialization.
• Select Units and Codes as per your project.
• we have selected Indian codes and units as Metric SI.

• Now select the uniform grid spacing.
• Select Single Footing.
• In single footing, Insert the dead loads and live loads.

Subgrade Modulas = FOS*SBC / Max. Settlement

FOS for soil is =3

S.B.C = 150Kn/m.sq

settelement for isolated footing = 25mm

subgrade modulus = 18000 KNm2

The compression axial load for load combination (1.5DL + 1.5LL) is 2000KN.

Load = 2000 /1.5

= 1333.3 KN

Dead load Breakup =1333.3/2

= 666.5 KN

Live load Breakup =1333.3/2

= 666.5 KN

So,

Footing Thickness is 800mm

• So single Footing is successfully added.

• New dialog box will appear
• Select Add new Material

• Now select Section Properties under Define Tab.
• Select Slab Sections.
• Select Add new properties in Slab Properties.

• Define properties for footing and Mat

• Define Footing for Stiff1

• Now define Load Patterrns

• Define Soil Subgrade Modulas / Area spring Property Data

• Assign Point Load as per below

• Define combinations as required

• Check Design Preference as concrete slab/ bream design

• Analyse the model using analyse option then click on check model the modelled structure is verified.
• The model is analyzed Successfully.

Safe Bearing Capacity:

Deformed Shapes:

Two way Shear Check:

• Punching shear seem to be greater than 1 so we have to increase the depth of footing or any other parameter

Bending Moment:

Shear Force:

Flexural Reinfoecement Design foe Footing Slab:

Result:

• We have designed the isolated footing provided in week 11 challenge on SAFE.