Estimating Sheet

# Rectangular Spread footing analysis and design

Construction Software ExcelCalcs is a spreadsheet based useful program that can be used for analysis of RECTANGULAR SPREAD FOOTING. ExcelCalcs subscribers (Subscribe here) will be able to download this calculation sheet.

This spreadsheet program is written in MS-Excel for analyzing rigorous rectangular spread footings through equal to 8 total piers, and for either uniaxial or biaxial resultant eccentricities.Overturning sliding. If required, uplift stability checks can be done.

The calculation can also be made for consequent gross soil bearing pressures at the four (4) corners of the footing. The utmost net soil bearing pressure can also be worked out.

This workbook program is comprised of five (5) worksheets, which are explained below:

• Footings (Table) - Numerous rectangular spread footings analysis and design (table format).
• Footings (Pier Table) - Numerous rectangular spread footings - pier analysis (table format).

Program Propositions and constraints:

1. This program believes that the spread footing is actually "rigorous", in order that the bearing pressure is allotted linearly on a uniform soil.(Note: the original footing is usually not "rigorous", neither is the pressure under it, is allotted linearly. Though, it is detected that solutions obtained through the hypothetical "rigid" concept are passable and normally produce a conservative design.)

2. This program believes an orthogonal X-Y-Z coordinate system by the origin situated at the centroid of the footing in plan (footprint)."Right-Hand-Rule" sign convention is applied for input of all pier coordinates together with all applied forces and moments at piers.

3. This program will deal with 1 up to eight (8) total piers placed anywhere on the base of the footing. Piers are calculated in any preferred order.

4. This program does not verify the original calculated soil bearing pressure toward a specified & acceptable soil pressure. It is executed in order that the coverage of suitable overstress is dependent on decision of the user. But, in each case, it should be verified by the user.

5. This program does not apply a specific acceptable value for the safety factor toward overturning. But, a least value of 1.5 to 2.0 is recommended, on the basis of the specific conditions.(A "Footing is unstable!" error message is given when the factor of safety toward overturning is < 1.0.Then the user should modify the footing dimensions or else other parameters.) 