22 October 2025
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Eurocode 3 (EN 1993-1-1:2005) now supports multiple segments defined by Lcr for the Lateral Torsional Buckling check. The software calculates the C1 factor and the capacity for each segment. The C1 factor is calculated using the equation proposed by M.A. Serna et al. (2006) for lateral bending and warping free at both end supports. |
23 September 2025
Multiple changes and improvements the American design module for Cold-formed Steel Members (AISI S100-16 ASD, AISI S100-16 LRFD and AISI S100-16 LSD):
- Updated shear area calculation for the minor axis of Z-sections to consider only one flange.
- Fixed bug in shear area calculation for the major axis of hat sections.
- Fixed bug in shear area calculation for the minor axis of channel sections.
- Section dimensions are now included in the report.
- Moved the properties and dimensions table to the top of the report.
- Added section dimension checks per Table B4.1-1.
- Added support for full bracing in compression to skip lateral-torsional buckling checks.
- Fixed bug related to user-defined K values.
- Default value of Cb = 1 is now used when calculation is not possible.
- Default value of Cs = 1 is now used when calculation is not possible.
- Added calculation of Cb for minor axis bending.
- Added calculation of Ctf (previously always set to 1).
- Changed elastic section modulus of Z-sections from the geometric axis to the principal axis.
- Minor axis bending report is now always shown, even when the moment is zero.
- Fixed incorrect references in the report.
- Fixed unit-related bug affecting DSM factors.
18 September 2025
- EN 1993-1-3:2006 (Eurocode for Cold-Formed Steel): Added calculation of lateral-torsional buckling capacity for multiple segments within a design member based on user-defined unbraced lengths.
11 September 2025
Multiple changes and improvements the American design module for Cold-formed Steel Members (AISI S100-12 ASD and AISI S100-12 LRFD):
- Changed the value of r (radius of gyration) used in flexural buckling capacity calculations to rmin instead of the radius from the axis under consideration.
- Lateral-torsional buckling results are now displayed even when the moment is zero.
- Corrected wrong variable names in the report.
- All section properties are now reported in the geometric axis.
- Fixed incorrect references in the report.
- Corrected values for plastic modulus and moments of inertia in the report.
- Updated the shear area for Z-sections in the minor axis to consider only one flange.
- Improved the calculation of effective section properties.
- Changed the default axis for hat sections to consider the symmetric axis as the Z-axis.
- Fixed an issue where the user-defined Cb value was not applied correctly.
- Fixed unit handling for lengths in lateral-torsional buckling calculations.
- The mono-symmetry constant (j) is now always considered positive.
- Resolved issues when moments were set to zero.
- Added lateral-torsional buckling checks for the minor axis in both positive and negative bending.
- Added positive and negative bending checks for all relevant calculations.
23 August 2025
- Fix the formula used for the reduction factor for outstand elements in EN 1993-1-3:2006 when the slenderness ratio is less than 0.748 as per EN 1993-1-5:2006 clause 4.4(2).
- Improve the section classification algorithm in EN 1993-1-5:2005 to use the critical class from the existing loading conditions. Previously it was using the critical class from all the loading conditions even if those were not present.
- Fix the forces used for the design of a member composed by multiple colinear elements in AS 1720:2010. Previously, the forces were considered over-conservatively by superposing the effect of all the elements.
19 July 2025
Multiple changes and improvements the European design module for Structural Steel Members (EN 1993-1-1:2005):
- The section classification was improved, including the addition of a table detailing the variables involved in the classification calculations.
- Clause 6.3.1.2(4) related to axial buckling capacity to determine whether the verification check can be omitted was included.
- Included Clause 6.3.2.2(4) related to bending capacity to assess whether the verification check can be omitted.
- Added flexural-torsional buckling checks for non-square RHS sections and T-sections.
- Added Clause 5.4.1(3) for singly symmetric sections, establishing their classification as Class 3 when subjected to bending about their non-symmetric axis.
- Added Clause 6.2.8 concerning the reduction of bending capacity due to high shear stress. Additionally, the check has been incorporated into both tension and compression verifications, as it is essential for combined checks.
- The rupture tension check has been incorporated, with the net area by default set equal to the gross section area.
- The parameter C1 for the buckling critical moment (Mcr) is now set to 1 by default, with the option for the user to specify a custom value.
- The formula for calculating the shear area of T-sections has been modified to yield a more accurate value.
- The parameter λlto has been changed from 0.2 to 0.4 for HSS sections.
- General enhancement of the report, including the addition of station information and load combinations considered in the check. Effective lengths have also been included in the report within their respective checks.
04 June 2025
Multiple changes, improvements and fixes in the Australian Cold-Formed Steel Design Code AS 4600 2018:
- Add a clear warning to the report when the DSM factors are not defined for a given section.
- Add inputs for user-defined correction factor for distribution of forces (kt) and Net Area Factor (An) to calculate the section capacity of a member in tension.
- Set the shear modulus of elasticity (G) to the fixed value of 80 x 103 MPa as specified in D1.1.1.2, this can be adjusted in the member design module settings.
- The coefficients CTF and Cs for singly-symmetric sections are now properly calculated as per D2.1.1.2. Previously, CTF was fixed to 1.0 and Cs was inverted for hat sections.
- Calculate the property Iyc for Zee sections as half of the second moment of inertia in the minor axis to compute Mo for point-symmetric sections.
- Remove the Load Height (load_height from the API) and Longitudinal Load Position (longitudinal_load_position from the API) inputs in the restraints input table to completely remove the method to determine the effective length for member bending capacity borrowed from AS 4100 2020 and NZ 3404 1997.
- Rename the Continuous input in the restraints input table to Global Buckling Bracing, with options: Unbraced, Top, Bottom, Both (unbraced, top, bottom, both from the API, respectively). When braced, the segment capacity for global buckling will be taken as the section's yield capacity under bending and compression.
- Add an input for the effective length factor for the twist compression segment (Kx) for user-defined factors (Kx from the API).
- Add inputs for a single effective length factor (KLT) for Lateral-torsional buckling in the major and minor axes for user-defined factors (kltz and klty from the API) to replace the previous three factors borrowed from AS 4100 2020 and NZ 3404 1997.
- Review all the section properties used in the calculations making sure the values are correct, and move the section properties report to the beginning of the detailed report.
- Use always the positive value of the Monosymmetry constant (β) from the Section Builder. Previously we were using the positive and negative value for positive and negative bending in the non-symmetry axis which was incorrect.
- Improve wording and remove unnecessary/repeated sections of the Detailed Report.
Multiple changes, improvements and fixes in the American Cold-Formed Steel Design Code AISI S100 2016:
- Remove the Load Height (load_height from the API) and Longitudinal Load Position (longitudinal_load_position from the API) inputs in the restraints input table to completely remove the method to determine the effective length for member bending capacity borrowed from AS 4100 2020 and NZ 3404 1997.
- Rename the Continuous input in the restraints input table to Global Buckling Bracing, with options: Unbraced, Top, Bottom, Both (unbraced, top, bottom, both from the API, respectively).
- Add an input for the effective length factor for the twist compression segment (Kx) for user-defined factors (Kx from the API).
- Add inputs for a single effective length factor (KLT) for Lateral-torsional buckling in the major and minor axes for user-defined factors (kltz and klty from the API) to replace the previous three factors borrowed from AS 4100 2020 and NZ 3404 1997.
Minor improvement in the Australian and New Zealand Structural Steel Design Code AS 4100 2020 and NZ 3404 1997:
- Add option to automatically determine the longitudinal position of the load for each segment to calculate the load height factor (k1) as per table 5.6.3(C)
29 April 2025
- Display the correct capacity in the summary report for NDS 2018. Previously, the report was showing the minimum capacity instead of the capacity associated with the critical utilization ratio. This issue only affected the summary report display; the underlying calculations were correct and remain unchanged.
14 February 2025
AS4100-2020
- Resolved an issue where effective length value was being used in the calculation of nominal member capacity (Nc) for combined actions capacity as per Clause 8.4.2.2. This resulted in conservative results for member combined actions capacity.
AS4100-1998: A comprehensive second round of testing performed with the following changes made. Please note that none of these issues were found in the AS4100-2020 module which went through a third round of validation.
- Tension rupture checks have been added, which may affect tension capacity (PhiNt) values.
- Issues resolved involving form factor calculations (kf) for some I-sections and SHS shapes. This previously resulted in some non-conservative results for section compression capacity (PhiNs).
- Member axial buckling capacity about the major/minor axis calculations updates for a number of shapes. This previously resulted in non-conservative results for member compression capacity (PhiNcy & PhiNcz).
- Major axis effective section modulus (Zez) was being underestimated for PFC sections. This previously resulted in conservative results for section moment capacity (PhiMsz).
- Minor axis effective section modulus (Zey) was being underestimated for I-sections. This previously resulted in conservative results for section moment capacity (PhiMsy).
- Effective section modulus (Zez, Zey) were being overestimated for some PFC and SHS/RHS shapes, which has been resolved. This previously resulted in non-conservative results for section moment capacity (PhiMsz).
- Major axis shear capacity was being overestimated for some I-sections and SHS shapes. This previously resulted in non-conservative results for section shear capacity (PhiVvy).
23 January 2025
Multiple changes and improvements the European design module for Cold-Formed Members (EN 1993-1-3:2006):
- Enhanced calculation of plasticized sections based on stress gradients about the geometric axis. Improvements and fixes were implemented following an independent third-party review.
- Added support for Z-sections with equal and unequal flanges.
- Extended support to channel and lipped channel sections with unequal flanges (previously limited to equal flanges).
- Reports now include visual representations of plasticized sections for each limit state.
15 January 2025
- Add a basic stress check for torsion as per Eurocode 3 (EN 1993-1-1:2005).
09 January 2025
Multiple changes, improvements and fixes for NDS:
- Minor updates to labels and tooltips to fix typos and add precision.
- Switched all units to "psi" in the report to simplify checks and formulas.
- Fixed a bug which created an error when members were deleted from the "Design Members" table.
- Added calculations steps for C_L, F_cE1, F_cE2 and F_bE to the report.
- Added support for negative moments. When negative moments are used, F_bx- is now considered.
- Fixed import bug for the "Spruce-Pine-Fir (S) (E=2.0_and_higher)" material.
- Simplified "Import Material" menu by pre-selecting imperial and wood values.
- Set size factor C_F = 1.0 for compression and tension strength checks of sawn members.
- Updated the value of F_cE to use the minimal value of E_xmin or E_ymin for glulam beams.
- Added the reductions for E_x and E_xmin for glulam members with 15 laminations or more.
- Added the F_bx reduction for members over 16 inches high.
- Added the F_vy reduction for members with 4 laminations or less.
- Set C_V = 1.0 for bending of glulam members when used in standalone. Updated the tooltip accordingly.
- Added the intermediate step of converting the section to an equivalent square section before calculations for poles.
31 October 2024
Multiple changes, improvements and fixes in the American Cold-Formed Steel Design Code AISI S100 2012:
- Change default value for "Cb" from 1 to calculated value.
- Add value of the section modulus “Sxp” and “Syp” to the report.
- Solve bugs in the calculation of effective properties in all supported sections. All the effective properties are now calculated according to AISI S100 2012 (Chapter B ELEMENTS).
- Fix bug in the calculation of “Sfy” in the principal axis. It is now properly calculated using the properties in the principal axis.
- Fixed orientation of Hat sections to use axes as defined in the Standard. The symmetric axis is the X axis.
- Fix a bug in the lip angle for the Z section, taking it directly from the section properties. This issue was affecting the section properties calculation.
- Consider Lateral-torsional and distortional buckling in the combined compression and bending strength.
- Add calculation of “Se” in the minor axis for Zee, Lipped Zee and Hat sections.
- Fix print issue in the report of “sigma_ey”.
- Standardize the number of decimal values in the report.
- Allow design of any section from the database from the supported shapes. Previously it was restricted to some of them.
- Fix value of h in the shear check.
- Delete unnecessary texts in the report.
- Improve section graphic in the report.
23 October 2024
- Support cold-formed European database shapes with equal flanges in the European design code (EN 1993-1-3:2006).
- Improve the general appearance of the report for EN 1993-1-3:2006.
- Fix some calculation issues in the effective section properties in EN 1993-1-3:2006.
21 August 2024
- Support South African Steel database shapes in the Australian, European and American design codes.
- Support South African Cold Formed Steel database shapes in the Australian and European design codes.
UI Improvement
Improve the error messages with guidance on how to fix them: issues with ill-defined restraints, section properties missing or not supported manufacture process.Calculation Issue
Fix in the nominal flexural strength for Compression Flange Yielding for W shapes in AISC 360-16. The wrong modulus was being used to calculate it.- Improve the appearance of some sections of the report in AISC 360-16 for HSS and CHS.
05 August 2024
UI Improvement
The design member IDs now match the corresponding S3D element IDs in the design codes this was not the case and appeared to be randomly/sequentially assigned (AS 4100:2020, NZS 3404:1997, AS/NZS 4600:2018, AISI S100-16, EN 1-3 2006).Calculation Issue
Design modules AISC 360-16 and AISC 360-10 were independently reviewed and validated by engineers. From that review, the following changes were applied:
- Improve general appearance of the report, fixing some math rendering issues and removing some irrelevant information.
- Add additional information of the section properties to the report.
- Fix “Qa” calculation for HSS (Hollow Structural Section). Affects AISC 360-10.
- Fix wrong classification in the report for HSS. Affects AISC 360-10.
- Fix “be” and “Ae” calculation for HSS. Affects AISC 360-16.
- Add missing sections to the report for HSS: web local buckling, lateral-torsional buckling, major bending. Affects AISC 360-16.
- Add missing checks for slender web in W section: major bending. Affects AISC 360-10.
- Fix “rt”, “Lp”, "Iyc" calculations for W section. Affects AISC 360-10 and AISC 360-16.
- Fix “Qa” and “Rpg” calculations for W section. Affects AISC 360-10.
- Add missing check for non-compact, slender web, and bending major for W section. Affects AISC 360-16.
- Add lateral torsional formula for W section. Affects AISC 360-16.
- Fix "lambda_w" calculation for C (Channel) section. Affects AISC 360-10 and AISC 360-16.
- Fix torsional and flexural-torsional buckling calculation checks for compression in T section. Affects AISC 360-16.
- Add missing flexural-torsional check for Angle section. Affects AISC 360-16.
- Add lateral torsional check for T section. Affects AISC 360-16.
- Fix bug in local buckling of Tee Stems calculation for T shape. Affects AISC 360-16.
- Fix bug in "Mp" calculation for T shape. Affects AISC 360-16.
18 July 2024
BETA tags removed for AS 4100:2020 and NZS 3404:1997 after an independent review and validation by engineers. From that review, the following changes were applied:
- Use different yield stresses for each section component depending on its thickness. This applies to database materials included in AS 4100:2020 Table 2.1 and NZS 3404:Part 2: 1997 Table C2.2.1.
- Use as-rolled as the plate's origin for custom welded-plates sections. Universal Beams and Universal Columns use flame-cut. This affects the member compression check in the major and minor axes.
- Support user-defined parameters for the tension check. Users can modify the values for kt (correction factor for distribution of forces) and factor to calculate An.
- Include the flanges' thickness in the web area for shear capacity in hot-rolled sections.
- Improve the calculation of the effective area for all sections.
- Fix the calculation of the monosymmetry section constant (Beta) for Tee sections.
- Add a setting to skip a stress analysis to find the average to maximum shear stress ratio and use approximate formulas. By default, the shear stress analysis will be used.
- Include in the report the calculations and results for determining "Full Lateral Restraint" on the critical segment.
- Bug fixed in the assignment of cross-section restraint to take into account the restraint conditions of the non-critical flange.
- The longitudinal load position factor should be calculated by the software instead of being a user input, as it might vary from load combination to load combination. At the moment, users have to select a conservative value for all load combinations. In a coming version, the software will calculate it automatically using the loading conditions in the model.
- Default the load height to 'top flange' in all the segments because it is more conservative and aligns with most real-life scenarios.
- UI/UX improvements to the UI, removing unused inputs and smoothing the workflows to Join/Split/Auto-group members.
03 June 2024
- NEW: Eurocode for cold-formed members (EN 1-3 2006) is now available in S3D. Supported section shapes: Channel, Channel with Lips, and Hat.
14 March 2024
- DSM factors entered for custom template shapes are properly saved and loaded.
- Design sections are not filtered by manufacturing process anymore but rather by their section database.
01 November 2023
- NEW: AISI S100-16 ASD, LSD and LRFD is now available in S3D.
- NEW: Filterable columns can be used in the Members Table for Length, Material ID and Section ID when using in S3D for the older V1 codes.
- NEW: Speed improvements for the Members Table when using in S3D for the older V1 codes.
31 January 2023
- NEW: Added restraints to AS/NZS 4600-2018.
24 January 2023
- NEW: Added round and rectangular bar sections to AS4100-2020 and NZS 3404-1997.
9 December 2022
- NEW: Support for Tapered I-shapes in AS4100-2020 and NZS3404-1997.
30 November 2022
- NEW: Improved members table by filtering the table when selecting members via the graphics.
- NEW: Ability to apply restraints to members.
- NEW: Restraints will be displayed in 3D graphics.
- NEW: Auto-group restraints.
04 October 2022
- NEW: AS 4100-2020 is now available.
- NEW: AS/NZS 4600-2018 is now available, using the Direct Strength Method (DSM).
- NEW: Member Restraints available for NZS 3404-1997 and AS 4100-2020 which allows users to add pseudo-restraints for more accurate calculations.
20 December 2021
- NEW: New Zealand code (NZS 3404-1997) now available in standalone, beam and S3D.
01 November 2021
- Interaction factors (kyy, kyz, kzy, kzz) can now be manually adjusted for each member in Eurocode.
21 December 2020
- NEW: Download all individual member design reports to a ZIP file.
10 December 2020
- NEW: Indian code (IS 800-2007 LSM and IS 800-1984 WSM) now available in standalone, beam and S3D.
30 September 2020
- NEW: New input data for dealing with member bracing and continuous members.
21 October 2019
- NEW: British code (BS 5950-1:2000) now available in standalone, beam and S3D (beta-stage development).
26 July 2019
- NEW: Cold-formed steel codes now available for USA (AISI S100-12 ASD/LRFD) in standalone, beam and S3D (beta-stage development).
15 July 2019
- NEW: Entry table system for "Design Members" table in "Members" tab. This datasheet behaves similar to MS Excel which should make data-entry a little easier. It is possible to copy/paste via MS Excel also.
24 June 2019
- NEW: T-shapes and Angles now available for design in Eurocode.
- NEW: Grouped elements of S3D are now integrated with the design results. This makes for easier viewing of results for similar members when Groups are used in S3D.
22 May 2019
- NEW: Filter for results table which makes viewing results a little easier.
- NEW: Added "Worst LC" to results so that it's known which load combination is used for the calculations of each member.
17 May 2019
- NEW: T-shapes and Angles now available for design in CSA S16-14.
02 April 2019
- Adjusted NDS® UI to resolve lagging UI issues with large tables when many members are in the structure.
18 March 2019
- NEW: Added AS1720 (Australian Timber) design code in beta-stage development.
24 October 2018
- NEW: The design module now supports saving/opening files with the file manager. It can be accessed via the "File" menu in the top bar.
18 October 2018
- NEW: NDS® 2018 ASD/LRFD now available in Standalone, S3D and Beam.
24 September 2018
- NEW: The new Material Database has been integrated.
17 April 2018
- NEW: The braced length (Lb) can now be manually set in Integrated (Beam and S3D) mode via the members table.
9 April 2018
- NEW: Full design reports with all related design calculations are now available for AISC 360.
- NEW: Sections do not need to be added from the database to be designed. General sections can now be designed provided that they are a supported shape.
18 December 2017
- NEW: CSA S16-14 now available in Standalone, S3D and Beam. I-shape, HSS and channels can be designed in this first release.
1 November 2017
- NEW: AS 4100-1998 now available in Standalone, S3D and Beam. I-shape, HSS and channels can be designed in this first release.
25 October 2017
- NEW: Eurocode 3 check for Combined Buckling (Bending + Compression).
12 September 2017
- NEW: Eurocode 3 now available in Standalone, S3D and Beam. I-shape, HSS and channels can be designed in this first release.
6 July 2017
- NEW: AISC 360-10 LRFD provision now available in Standalone and S3D Integrated. All shapes can be designed (I-Shapes, T-Shapes, Rectangular HSS, Round HSS, Channels and Angles).
22 June 2017
- NEW: T shapes now available for design in AISC 360-10.
14 June 2017
- NEW: Channels and Angles now available for design in AISC 360-10.
6 June 2017
- Fixed issue with DNV Imperial units.
- Fixed issue where multiple DNV Lifting Nodes could not be specified in S3D Integrated.
1 June 2017
- NEW: Released the first SkyCiv Design Codes which can be used in standalone or integrated with analysis (SkyCiv S3D).
- NEW: AISC 360-10 available (only I-Shapes, Rectangular HSS, Round HSS at this stage).
- NEW: DNV 2-7.1 available.
