How many times have you been in a kick-off meeting, and the architect is already pressing you to offer up beam and column sizes for the building in question?  Or how do you usually answer when prompted to estimate the total steel tonnage on a project for preliminary cost estimates?

In the September 2023 SEU session, John A, Kennedy, SE, PE, from Structural Affiliates International, Inc.presented Rules of Thumb for Steel Design.  John shared some quick reference approximations for mechanical properties of steel sections.  He also identified some rules of thumb for the design of beams, columns, and trusses, and shared some design examples using these rules. 

John offered an excellent resource which includes many of these quick reference rules in the form of a printable pocket card.  Using this card, engineers can make on-the-spot determinations during meetings or preliminary design to get a reference for the size of beam or columns needed.  Click here to print your own copy.

The reference card uses units of measurement that engineers typically use, such as weight in pounds, area in square inches, and axial capacities in kips.  The card offers all of the economy steel sections as well as the column widths for common sizes.  The equations that are shaded can be used for 50 ksi steel.  

John noted that rules of thumb are approximations and are not always conservative.  Using these approximations should in no way take the place of a rigorous structural analysis; however, these rules of thumb are quick, easy to use, and really simplify some basic calculations to make useful approximations when time is of the essence.