“TORSION9” — SIMPLIFIED TORSION ANALYSIS FOR STEEL BEAMS
“TORSION9” is a spreadsheet program written in MS-Excel for the purpose of simplified analysis and code
checking of steel beams subjected to torsional loading. Specifically, six (6) different beam and loading
configurations can be analyzed / code checked per the AISC 9th Edition Allowable Stress Design (ASD) Manual.
Both actual and allowable stresses are computed, with the final result being a computed “stress ratio” of actual
stress/allowable stress. Finally, the total angle of twist resulting from the torsional loading is determined.
This program is a workbook consisting of seven (7) worksheets, described as follows:
Worksheet Name Description
Doc This documentation sheet
Cantilever – Ecc. Conc. Load Cantilever Beam with Eccentric Concentrated Load at Free End
Simple Span – Ecc. Conc. Load Simple Span Beam with Eccentric Concentrated Load Applied at Midspan
Cont. Span – Ecc. Conc. Load Continuous Beam with Eccentric Concentrated Load Applied at All Midspans
Cantilever – Ecc. Unif. Load Cantilever Beam with Eccentric Uniformly Distributed Load
Simple Span – Ecc. Unif. Load Simple Span Beam with Eccentric Uniformly Distributed Load
Cont. Span – Ecc. Unif. Load Continuous Beam with Eccentric Uniformly Distributed Load on All Spans
Program Assumptions and Limitations:
- The simplified torsion analysis used is this program is based on the following reference:
USS Steel Design Manual (1981), Chapter 7: Torsion (Figures 7.9 & 7.10, pages 157-169),
by: R.L. Brockenbrough & B.G. Johnston
- This program is valid for AISC W, S, M, and HP shapes.
- This program uses the database of member dimensions and section properties from the “AISC Shapes
Database”, Version 3.0 (2001) as well as the AISC 9th Edition (ASD) Manual (1989).
- This program follows the procedures and guidelines of the AISC 9th Edition Allowable Stress (ASD) Manual
- When the value of ‘Lb’ is input = 0 (or actually <= 1.0 ft.), this program will use a value = 1.0 ft.
- This program utilizes an “Allowable Stress Increase Factor” (ASIF) which is a multiplier of any of the
calculated allowable stresses Fa, Fbx, and Fby and also the Euler column buckling stresses F’ex and F’ey.
It is used and appears ONLY in the stress ratio calculation. Typically a value of 1.0 may be used. However, a
value of 1.333 may be used for load combinations which include wind or seismic loads.
- This program does not calculate or check shear or deflection in member
- This program does not consider deduction for holes in members subjected to tension.
- 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”.)