Yes, in the "BOEF.xls" workbook if you read the comment boxes off to the right side those comments and the resulting calculations will give you some guidance in selecting the effective strip width for a slab on grade to resist concentrated loads. For a thin slab I would stay on the conservative side with the effective width.

For slab on grade analysis/design, you could and probably should use my "GRDSLAB.xls" workbook. I use the "BOEF.xls" workbook mainly for analyzing combined footings and strips of mat foundations.

Alex

ok thanks!

Soils appear to have ability for soils to be in tension. Would not compression only springs be more accurate? or is there an explanation for soil tension springs? Thanks very much for your time and efforts with the spreadsheet.

andiamo,
This spreadsheet is based on the well known and reputed Roark reference, as cited in the "DOC" worksheet. Depending on the degree of flexiblity of the beam or slab/mat strip, as well as the nature of the applied loads, the solution for bearing pressures may show tension (uplift) at the ends. While we all know that soil cannot resist tension, what this does represent is that your situation is too flexible to distribute out the loads. This spreadsheet is not intended to be a replacement for a finite element model (FEM) analysis, and the solution/formulas do not directly involve the use of "springs". However, sometimes we either don't have the time or it may not be worth the extra effort involved to do an FEM analysis. This spreadsheet, when used and interpreted properly, can be a very quick and powerful tool for helping the engineer determine just how flexible or rigid a particular beam or slab/mat strip really is (or needs to be), and thus how much load distribution is actually occurring. Engineers often blatantly assume "rigidity" in their analyses. This spreadsheet can help either prove or disprove those assumptions.
Hope this helps.
Alex

It was brought to my attention that there was a "typo-error" in the "Beam on Elastic Foundation" worksheet of the "BOEF.xls" workbook. In calculation cell IS132, it should have been referring to cell B40, not cell B340 as it was. Actually, there was nothing in cell B340.

The program breaks up the beam length into 100 segments for the purpose of determining the maximum shears, moments, deflection, and bearing pressure, as well as for the purpose of plotting the graphs. The 100 segments will get you real close, but will not always assure that the exact maximums are captured. Thus to help improve the accuracy, the program also performs the calculations for 4 user designated x-distance locations from the left end, as well as the x-distance locations of the various loads. Cell IS132 was referring to the x-distance for Point Load #8. Since there was no value in cell B340, the value in cell IS132 for the x-distance became = 0. However, 100 segment graphed results were not affected by this "typo-error".

At the request of a few people, I have added a metric units version worksheet to the "BOEF.xls" (Beam On Elastic Foundation) workbook.

I also expanded on and added some input data validation and comment boxes to help further clarify the usage and application of this program.