CFS Version 5 Changes
Released November 2005

2004 North American Specification

CFS now supports the 2004 Edition of the "North American Specification for the Design of Cold-Formed Steel Members". This includes ASD and LRFD for U.S. and Mexico, as well as LSD for Canada. CFS continues to support the 2001 North American Specification and the 1996 AISI Specification with the Supplement 1 (1999). Specific changes from 2001 to 2004 are as follows:

  • Revision to list of applicable steels
  • Limit on strength increase from cold-work of forming
  • Revision to effective width of stiffened elements with circular holes
  • Revision to effective width of unstiffened elements under stress gradient
  • Revision to flexural members not subject to lateral-torsional buckling
  • Revision to combined bending/shear interaction equations
  • Revision to web crippling coefficients for multi-web deck sections
  • Revision to combined bending/web crippling interaction equations
Direct Strength Method

The 2004 Specification includes an appendix for the Direct Strength Method. This method provides an alternate design procedure to portions of the main specification. It utilizes elastic critical buckling values to predict axial and bending strengths of a member. CFS version 5 includes the following changes to support this method:

  • The Section Inputs window contains a new tab for entering elastic buckling values
  • The elastic buckling feature let's you assign buckling values directly to the section inputs
  • The Strength and Member Check calculations use the Direct Strength Method if selected
Calculation Trace Feature

One of the major enhancements in CFS Version 5 is the ability to report detailed steps of the internal calculations. This output includes the symbols used in the Specification, the values calculated, and the equation numbers used to perform the calculations. The following trace options are available:

  • Strength calculations
  • Member check calculations
  • Effective section properties
Other Enhancements
  • Shareable licensing option which utilizes a USB or parallel port key
  • Network capable sharing of this type of license
  • Section Wizard remembers your previous inputs to make the next section easier
  • New feature to report section and analysis inputs without having to print
  • New feature to shift section parts so the origin is at the center of gravity
  • Arrow keys may be used to change selected elements
  • Input limits were relaxed for some values (yield strain, minimum lip, etc.)
  • Analysis Wizard remembers your previous inputs to make the next analysis easier
  • Analysis window has a new tab for storing your own notes about the analysis
  • Analysis solver uses increased precision to improve calculated results
  • Elastic buckling feature provides mode shape for every solved length
  • Elastic buckling profile provides buckling values between solved points
  • Corrected shear yield limit check to apply only to stainless steel
  • Corrected column buckling stress for point-symmetric section connected to sheathing
  • Corrected member check for unsymmetrical parts in built-up members with connector spacing > 0
  • Corrected error that may occur when buidling section libraries on Windows XP
  • The 2002 ASCE specification removed the compression strength reduction for unstiffened channels, zees, and angles
  • Analysis diagrams combinations with no transverse loads are excluded to avoid division errors
  • Concentrated loads are shown at mid-point of load instead of left edge
  • Analysis check points now include locations adjacent to concentrated loads
  • Inflection points within cantilevers are now prohibited from being considered brace points
  • Corrected analysis bracing check on unsymmetrical section
  • Corrected web crippling calculations when analysis supports have different settings for fastened flanges
  • Fixed output format for analysis loads
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