Flat Bar and Plating Combination,
Framing Member Calculations
(English Units)

Description: This boilerplate template calculates combined member area property characteristics for a flat bar and the plating to which it is attached.  

  • This MathCAD document calculates the available area properties such as section modulus and moment of inertia.  It does not calculate the required section modulus which is obtained from sources similar to Reference B through D.  In other words two sets of calculations are needed.  First the required section modulus needs to be computed.  Then some available framing members are selected and their combined properties are computed on a electronic document, like this template, to see if the available members meet or exceed the required area properties.

  • The effective plating width, EPW, selected is the lesser of the ABS allowable [1983 Rules for Steel Vessels under 200 feet (61 meters)], 38 times the plating thickness (an industry rule of thumb), or the frame spacing (limited by geometry in this case).  If other classification society classing rules apply, these calculations should be modified to suit applicable the classification society requirements. 

  • For fabricated framing members the EPW thickness can be set to zero to obtain only the area properties of the custom framing member.

  • These calculations apply to English units. But the purchaser may change the template to apply to metric units.

  • The material for the framing member must be the same as for the plating member.  Another approach is necessary if this is not the case.  In other words, this approach will work for a steel frame on steel plating or an aluminum frame on aluminum plating.  It will not work for a aluminum frame on steel plating or a steel frame on aluminum plating.

There are advantages and benefits to this calculative method.  First this approach saves you time.  Many computations are quickly done on your input data.  Second this approach provides clear and neat documentation.  These computations can readily be submitted to U. S. C. G. or classification societies if requested.  Third this approach is cost effective because the calculative approach is already developed for you, research time is minimized to familiarization of concepts if necessary and not to time consuming development activities.

Electronic Document Type:  MathSoft MathCAD document           Cost: $7.50 US funds

Number of Pages: Inputs Page, Outputs Page (2 MathCAD pages).  Instructions and Use Terms Page (1 browser page).                


  • Geometric Properties of Framing Assembly

    • Support Length (or span) of framing member, inches

    • Support Width of framing member, inches

  • Flat Bar Framing Member Properties, diagram provided

    • Height of flat bar, inches

    • Thickness of flat bar, inches

  • Plating Properties

    • thickness of plating

  • Material Properties

    • material density, select steel or aluminum, values provided


  • Area Properties for combined section:

    • Total Area, square inches

    • Centroid of combined area, inches

    • Moment of Inertia about centroidal axis, in4

    • Section Modulus for combined section, in3

  • Weight Properties of combined section

    • Unit Weight, pounds per foot for combined section

Recommended Reading:

  • Reference A: AISC Steel Construction Manual, American Institute of Steel Construction, Chicago, IL.

  • Reference B: ABS Rules for Building and Classing Steel Vessels Under 210 feet (61 meters), 1983, American Bureau of Shipping, Houston, TX.

  • Reference C: Arthur Edmunds, Designing for Power and Sail, Bristol Fashion Publications, 1998, Harrisburg, PA.

  • Reference D: John S. Spencer, Structural Design of Aluminum Crewboats, Marine Technology, July 1975 Issue, Society of Naval Architects and Marine Engineers, Paramus, NJ.

  • Reference E: Bruce Roberts-Goodson, The Complete Guide to Metal Boats, International Marine, 2001, Camden, ME.

  • Reference F: Dave Gerr, Boat Strength for Builders, Designers and Owners, International Marine, 2000, Camden, ME.

  • Reference G: Rawson and Tupper, Basic Ship Theory, Longhams, London

  • Reference H: SNAME, Principles of Naval Architecture, Society of Naval Architects and Marine Engineers, Paramus, NJ.

  • any strength of materials text 

Terms: Prior to purchase, read our End User License Terms.

Download Now: click the following hyperlink to pay $7.50 fee and then immediately download the zip file containing the template.

Minimum System Requirements: Windows 95/98/NT/2000/XP/Vista/Windows7

Sample: A sample portion of a page is shown below.