Product bulletins

Tekla Structural Designer product bulletin October 2018 (PBTSD-1810-1)

Résumé of issue Under the US headcode (for Customary and Metric Units) for HSS sections in torsion, previous versions of Tekla Structural Designer only took account of Yielding strength when evaluating torsion with combined forces and therefore may have underestimated the utilisation ratio when Local Buckling (or LTB) was more critical than Yielding. Occurrence This issue relates to Tekla Structural Designer 2017i (version 17.1.0.64 released in September 2017) and all subsequent versions.
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Tekla Structural Designer product bulletin September 2018 (PBTSD-1809-2)

Résumé of issue This issue relates to the design of concrete columns for the United States Head Code. For columns with one or more holes in their section, the area of concrete removed by the hole(s) was ignored when calculating the Ultimate Axial Resistance, resulting in an incorrectly higher resistance. Since in ACI 318 the ultimate axial resistance value is capped to reserve moment strength for the code prescribed minimum level of design load eccentricities, there was potential for this to produce an un-conservative design result. Occurrence This issue relates to Tekla Structural Designer
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Tekla Structural Designer product bulletin September 2018 (PBTSD-1809-1)

Résumé of issue This issue relates to the design of spread footings (pad bases) to the USA design code. For some geometries of footing a punching (two-way) shear check is not performed when the critical failure section spans across the footing reaching opposite sides, potentially producing an unconservative design. It is expected this would be critical only in less common situations of heavily loaded footings on very high bearing capacity soil which can result in smaller plan dimension footings subject to relatively high internal design forces. Occurrence This issue relates to Tekla
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Tekla Structural Designer product bulletin August 2018 (PBTSD-1808-2)

Résumé of issue This issue relates to the design of steel beams and columns forming part of a seismic force resisting system (SFRS).  In the following specific circumstances, the required strength value used in the Seismic Strength checks is incorrect producing a potentially unconservative result: Head Code set to United States. Models for which non-linear analysis is required (typically, but not exclusively, those with tension only bracing). Beams and columns in all kinds of SFRS in which they are subject to seismic strength checks. Seismic Wizard Analysis Procedure set to ELF. The Design
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Tekla Structural Designer product bulletin August 2018 (PBTSD-1808-1)

Résumé of Issue This applies to all Head Codes and relates to the checking of parts of a model following an analysis using the Structure Tree context menu check commands, such as ‘Check Plane’ and ‘Check sub structure’ etc.  For these commands no check was performed for steel members in the selected part and their design status was not updated.  It is possible the engineer could miss this and think a design had been performed.  Note that the context menu design options such as ‘Design Plane’ did function correctly. Occurrence This issue relates only to Tekla Structural Designer 2018 Service
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Tekla Structural Designer product bulletin Mar 2018 (PBTSD-1803-2)

Résumé of Issue This issue relates to the properties of plated sections created using US Customary units, hence only the US Head code is likely to be affected.  For US Customary units, some plate dimensions were stored with insufficient precision resulting in a loss of accuracy for plated section properties.  We would note that  in general the issue affected principally analysis, as design for plated sections was not carried out in previous releases for the US Head code.  Additionally, since plated sections and their plates are more commonly large (in which case the lower precision would have
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Tekla Structural Designer product bulletin March 2018 (PBTSD-1803-1)

Résumé of Issue This issue relates to the design of steel braces for the BS Headcode (All Countries).  For braces subject to tension using double-angle sections, the tension capacity check used the gross area Ag of the brace, rather than the net area Ae, potentially producing an unconservative design result. Occurrence This issue relates to  Tekla Structural Designer 2017i (version 17.1.0.64 released in Sept 2017) and subsequent releases.* *The previous Product Bulletin on this topic PBTSD-1801-3 was incorrect in this regard.
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Tekla Structural Designer product bulletin February 2018 (PBTSD-1802-3)

Résumé of issue This issue relates to the design of steel braces for the BS Headcode (All Countries).  For braces subject to tension using flat, double-angle and structural hollow section (SHS, CHS & RHS), the tension capacity check uses the gross area Ag of the brace, rather than the net area Ae , potentially producing an unconservative design result. Occurrence This issue relates to Tekla Structural Designer 2015 (version 15.0.0.40) released in March 2015 and all subsequent releases
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Tekla Structural Designer product bulletin February 2018 (PBTSD-1802-2)

Résumé of issue This issue relates to the analysis model for buildings with 2-way concrete slabs supported by beams or walls for all Head Codes.  In specific and relatively rare circumstances the concrete slab 2D element mesh was not correctly connected to a supporting beam or wall.  Resulting errors in design forces would tend to be conservative for slabs but potentially unconservative for supporting beams/walls.  Where this issue occurred it would generally be clearly apparent from deflections and unexpected failure of slab design due to it spanning a greater distance. Occurrence This issue
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Tekla Structural Designer product bulletin February 2018 (PBTSD-1802-1)

Résumé of issue This issue relates to the de​sign of steel cantilever beams for the US Headcodes.  For the Live and Total Deflection checks, in some circumstances incorrect design values of zero were used and an incorrect pass status assigned. Occurrence This issue relates to Tekla Structural Designer 2017i SP2 (version 17.1.2.71 released in Oct 2017) in which it was introduced, and the subsequent Service Pack 3.
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Tekla Structural Designer product bulletin November 2017 (PBTSD-1711-1)

Résumé of issue This issue relates to the d​esign of steel Gable Posts to the Headcodes; Eurocode (all countries), BS (all countries). For the Eurocode, when subject to axial load and bending, the combined buckling check is not carried out. For the BS code, whilst combined buckling checks are carried out, they reference the incorrect flange and separate LTB checks are not undertaken. Both issues could lead to an unconservative result. However we would note that, in the most common application of Gable Posts, bending moment tends to dominate design and axial load is likely to be relatively
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Tekla Structural Designer product bulletin October 2017 (PBTSD-1710-2)

Résumé of Issue This issue relates to Composite Beam Design for All Head Codes.  For beams with the option “allow non-composite design” checked on and when designed as non-composite (due to composite design failure), the composite inertia was still used for deflection calculation resulting in an underestimate of deflections. Occurrence This issue relates to all versions since Tekla Structural Designer 2015 (version 15.0.0.40) released in March 2015.
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Tekla Structural Designer product bulletin October 2017 (PBTSD-1710-1)

Résumé of issue This issue relates to the design of flanged concrete beams (“T-beams”) to the US Head Code (ACI). In the following circumstances the calculated deflection was underestimated potentially resulting in a pass status rather than a failure: Options “Consider flanges” and “Include flanges in analysis” both enabled. Section 8.12 produced a smaller flange width for design than that used in analysis, or resulted in the flange being ignored for design. Occurrence This issue relates to all versions since Tekla Structural Designer 2015 (version 15.0.0.40) released in March 2015. 
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Tekla Structural Designer product bulletin September 2017 (PBTSD-1709-2)

Résumé of issue This issue relates to the design of concrete walls to all Head Codes. The concrete wall properties setting for the wall to be considered as restrained at a floor level, although active during program operation, was not preserved by saving. Hence, when a file was closed and reopened, any edited settings would be reset to their original values. If missed by the engineer, this could produce an unconservative result. Occurrence This issue relates to all versions since Tekla Structural Designer 2015 (version 15.0.0.40) released in March 2015.
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Tekla Structural Designer product bulletin September 2017 (PBTSD-1709-1)

Résumé of issue This issue relates to Imposed Load Reductions and the analysis & design of concrete walls to Head Codes BS (all countries) and Eurocode (all countries). The concrete wall properties setting for floors to be counted as supported, although active during program operation, was not preserved by saving. Hence, when a file was closed and reopened, any edited settings would be reset to their original values. If missed by the engineer, this could produce an unconservative result in the following circumstances: Buildings of > 2 stories. Imposed Load Reductions were enabled for
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Tekla Structural Designer product bulletin June 2017 (PBTSD-1707-1)

Résumé of Issue This issue relates to Isolated Foundation Pad Base design for the following Head Codes; BS (all countries), India and United States (ACI).  For rectangular bases the Passive Resistance used in the Sliding check is incorrect in that the resistance for the X-direction is transposed with that for the Y-direction.  We note the following: There is no impact if square bases are used throughout. Passive resistance is only a significant part of sliding resistance when vertical load is very low. Occurrence This issue relates to all versions since Tekla Structural Designer 2016 (version
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Tekla Structural Designer product bulletin June 2017 (PBTSD-1706-2)

Résumé of Issue This issue relates to the Design (Static) and Analyse All (Static) processes and the following Head Codes which feature an Amplified forces analysis method, Eurocode (all countries), BS (all countries) and Australia. The issue only occurs when this Amplified forces method is selected for Design. In some circumstances the amplification factor (termed kamp) is not being applied. It is clear when the issue occurs as it is flagged by warnings in the Process Window that Total reactions vs Applied loading do not balance and errors in the Load Summary check. Such errors and warnings
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Tekla Structural Designer product bulletin June 2017 (PBTSD-1706-1)

Résumé of Issue This issue relates to slab design and Punching Shear Checks for walls for all Head Codes. Punching checks applied to walls with automatically reduced perimeters (accounting for the effects of adjacent openings) did not correctly detect the wall axial loading and set VEd equal to zero. While this issue would be apparent in the punching check design details, a check was still performed which could have a pass status. Please note the following: While punching checks on walls are made they should be viewed with particular caution - see the Tekla Structural Designer Help topic ‘
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Tekla Structural Designer product bulletin May 2017 (PBTSD-1705-3)

Résumé of Issue This issue relates to slab design and punching shear checks for the BS and Eurocode Head Codes. For checks located at edges and corners of slabs, the full internal shear perimeter depth and breadth - termed Dperim and Bperim respectively - were incorrectly used instead of the effective (reduced) dimensions. For edge column checks this could result in an incorrect and unconservative applied shear stress value ( BS Head code). The issue could also affect the reinforcement ratio used for punching checks within slab patches for both edge and corner cases (BS and Eurocode). Note
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  • punching shear

Tekla Structural Designer product bulletin May 2017 (PBTSD-1705-2)

Résumé of Issue This issue relates to all Head Codes. In some circumstances perimeter loads are not correctly applied in the Grillage chase-down and 3D Building analyses. Where the issue occurs it will be apparent from errors in the Load Summary check. Occurrence This issue relates only to TSD 2017 (version 17.0.0.37) released in Mar 2017 (in which the Perimeter Load Feature was introduced) and the subsequent Service Pack 1 (version 17.0.1.41). Please read the attached PDF for full details of the issue.
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