# JOIST.xls

### Description

"JOIST" is a spreadsheet program written in MS-Excel for the purpose of analysis of steel joists considered as

simple-span beams subjected to virtually any type of loading configuration. Specifically, beam end reactions as well

as the maximum moments and deflections are calculated. Plots of both the shear and moment diagrams are

produced, as well as a tabulation of the shear, moment, slope, and deflection for the joist span. There are two

worksheets for selecting K-series and LH-series joists, and 2 worksheets which are the SJI Standard Load Tables.

This program is a workbook consisting of eight (8) worksheets, described as follows:

Worksheet Name

Doc - This documentation sheet

General Joist Analysis - General standard joist analysis for steel joists for non-standard loads

K-Joist Analysis - Analysis for typical, standard loaded, open-web K-series steel joists

K-Joist Table - Standard (SJI) load table for open-web K-series steel joists

KCS-Joist Analysis - Analysis for non-standard loaded, open-web KCS-series steel joists

KCS-Joist Table - Load table for open-web KCS-series steel joists

LH-Joist Analysis - Analysis for typical, standard loaded, longspan LH-series steel joists

LH-Joist Table - Standard (SJI) load table for longspan LH-series steel joists

Program Assumptions and Limitations:

1. For the "General Joist Analysis" worksheet, the following reference was used in the development of this program: "Modern Formulas for Statics and Dynamics, A Stress-and-Strain Approach" by Walter D. Pilkey and Pin Yu Chang, McGraw-Hill Book Company (1978), pages 11 to 21.

2. The "General Joist Analysis" worksheet on the joist span will handle a full length uniform load and up to eight (8) partial uniform, triangular, or trapezoidal loads, up to fifteen (15) point loads, and up to four (4) applied moments.

3. The "General Joist Analysis" worksheet will calculate the joist end vertical reactions, the maximum positive moment and negative moment (if applicable), and the maximum negative deflection and positive deflection (if applicable). The calculated values for the end reactions and maximum moments and deflections are determined from dividing the joist into fifty (50) equal segments with fifty-one (51) points, and including all of the point load and applied moment locations as well. (Note: the actual point of maximum moment occurs where the shear = 0, or passes through zero, while the actual point of maximum deflection is where the slope = 0.)

4. In the "General Joist Analysis" worksheet the user is given the ability to input two (2) specific locations from the left end of the joist to calculate the shear, moment, slope, deflection, as well as the stress ratios for shear and moment. This should be utilized when the maximum moment does not occur at the start or end of a segment.

5. In the "General Joist Analysis" worksheet, the plots of the shear and moment diagrams as well as the displayed tabulation of shear, moment, slope, and deflection are based on the joist span being divided up into fifty (50) equal segments with-one (51) points.

6. The "General Joist Analysis" worksheet will enable the user to either analyze an existing joist for new loads or determine the required total equivalent uniform load to be used to size a new joist.

7. The "General Joist Analysis" worksheet only analyzes the joist "as a whole" and does not perform checks on the individual components.

8. In the "General Joist Analysis" worksheet, the deflections calculated include a 15% increase above the values calculated using traditional "simple-beam" flexure to more closely match actual test results obtained by SJI.

9. For the "K-Joist Analysis" and "LH-Joist Analysis" worksheets, the Steel Joist Institute (SJI) Standard Load Table as well the "Recommended Code of Standard Practice for Steel Joists and Joist Girders" are used. The Standard Load Tables are built into each of these two analysis worksheets. The two worksheets will evaluate a user selected joist size, as well as display up to a maximum of 15 of the lightest joist sizes that are satisfactory for the loading and deflection criteria specified by the user. The bridging requirements are also determined.

10. This program contains numerous “comment boxes” which contain a wide variety of information including explanations of input or output items, equations used, data tables, etc. (Note: presence of a “comment box” is denoted by a “red triangle” in the upper right-hand corner of a cell. Merely move the mouse pointer to the desired cell to view the contents of that particular "comment box".)

**Calculation Reference**

AISC

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While your question is not related to this thread on the JOIST.xls workbook, nevertheless I will answer it here.

Yes, I have a workbook called "FOOTINGS.xls", which is pretty handy for footing analysis and design. The workbook can be found under "Strength", and then "Structural Details" sections of the Calculation Repository. Look on page 3.

The workbook is in "English" units. Sorry, but that's my "cup of tea", as they say. (lol)

Alex

Please help me know if we have an ExcelCalc file in order to analyze and design a single footing.

Thank you

JAHAN

The last mumber in a (Steel Joist Institute) joist is the "section designation", 1 through 12. The higher the number, the heavier the joist (wt./unit length), and the more distributed load it can safely carry. It used to be common place to refer to joists simply as "bar joists", because many times the members of joists were composed of bars/rods. The last number does not refer to a particular angle size, and has nothing to do with the specific member sizes.

I have done some retro-fit work in the past at existing facilities where roof joists were utilized. If you cannot obtain the shop drawings from the original joist vendor, then one has to literally take field measurements of the sections making up the joist. Also, if you do not have the original shop drawings or building project specifications, then you are faced with the question of the yield strength of the materials that were used in fabrication of the joists. Usually if you know approximately when the building was constructed, a call to a local joist vendor can be of some help.

Hope that helps.

Alex

The original is [here](/support/forum).

To elaborate, the calculated deflection ratio in cell B74 based on the allowable capacity loads should have used the maximum absolute value of the deflections from cells B72 and B73. The simple-span beam static analysis deflections that were calculated were factored up by 1.15 to better reflect actual test results by the SJI as is noted in the comment box. The original defection ratio in cell B74 does not reflect this 15% increase in deflection.

Likewise, the calculated deflection ratio in cell B91 based on the actual design loads should have used the maximum absolute value of the deflections from cells B89 and B90. Again, the simple-span beam static analysis deflections that were calculated were factored up by 1.15. The original defection ratio in cell B91 does not reflect this 15% increase in deflection.

By the way, these same errors DID NOT occur in the "General Joist Analysis" worksheet. So much for me being consistent! (lol)

I have corrected the logic in cells B74 and B91, and the "JOIST.xls" workbook has now been updated to version 1.6.

I have reviewed your comments pertaining to the KCS-Joist Analysis worksheet, and your are indeed correct!

The calculated deflection ratio in cell B74 based on the allowable capacity loads should have used the maximum absolute value of the deflections displayed in cells B72 and B73. These simple-span beam static analysis deflections that were calculated were factored up by 1.15 to better reflect actual test results by the SJI. The original defection ratio in cell B74 does not reflect this 15% increase in deflection.

Likewise, the calculated deflection ratio in cell B91 based on the actual design loads should have used the maximum absolute value of the deflections displayed in cells B89 and B90. Again, the simple-span beam static analysis deflections that were calculated were factored up by 1.15. The original defection ratio in cell B91 does not reflect this 15% increase in deflection.

I have made the corrections to the logic in cells B74 and B91 and the updated version of this workbook will be posted soon on this website.

By the way, these same errors DID NOT occur in the "General Joist Analysis" worksheet. So much for me being consistent! (lol)

Alex

Reiterating from before, in the user input data cells for distributed/partial distributed loads, my original intent was to place input data validation on the user input values of the end distances, "e", for the distributed loads, such that "e" must be >= "b", which would prevent the user from entering bogus values for "e". The input data validation for the "e" values should have each been tied to the appropriate cell for the beginning distance, "b". Problem was, I had all of the "e" distance cells tied to the "b" distance for only the first distributed load. I have made the corrections in both of the worksheets as required.

By the way, let me point out that these mistakes in input data validation also existed in the cells pertaining to the original design loads, not just for the new design loads that you discovered. Nothing like me being consistent, right? :laugh:

I will make the corrections in the input data validation for cells D21 through D27 as well as D41 through 47, and an updated version (1.5) of the "JOIST.xls" workbook will be posted.

Thanks for bringing this to my attention.

Alex

to see what i am talking about, enter the first load in row 40 that starts at 15 ft. and ends at 30 ft. then add another load in row 41 that starts at 0 ft and ends at 12 ft.... or any number less than 15 ft.

I hope you can find it...

The current version of this workbook is now 1.4.

This has now been corrected.

I took a really quick look (spot check) at the K-series joist tables in the SJI 2005 Catalog and compared it to the 2010 SJI Catalog. I did not see any real changes. Can you advise me on what differences that you are aware of? I wrote the JOIST.xls workbook several years ago, and in the past 10 years, working in heavy industrial projects, I have not had any exposure to nor need for joists.

Alex