Steel column base plate design enhancements - Eurocode

Tekla Structural Designer
2022
Tekla Structural Designer

Steel column base plate design enhancements - Eurocode

In Tekla Structural Designer 2022 the steel column base plate design checks have been significantly enhanced for Eurocode design.

Design for minor axis shear

The scope of steel column base plate design checks is enhanced for Eurocodes to consider minor axis shear. This was first introduced in release 2021 SP4.

Where previously an ignored forces warning was issued when minor axis shear existed, minor & biaxial shear is now checked for column base plates on columns with the following sections: I/H, CHS & SHS*.

*For RHS section columns, minor shear continues to be an Ignored Force (a warning is issued in the results viewer when it exists).

  • Shear force - this continues to be resisted as previously by friction alone, or the shear on bolts alone, or shear on bolts + friction, depending on the option set for “Horizontal Shear Transfer” in the base plate settings for Bolts.

    • The shear force resisted is the vector sum of the applied major and minor shear in the load combination. An example of the new checks carried out is shown in the picture below (for the “Friction and shear on bolts” option of “Horizontal Shear Transfer”).
  • Forces on welds - where direct contact in bearing is flagged on (in the base plate properties) then axial force on welds is taken as zero, otherwise:

    • For I/H sections, the flange welds are designed for the vector sum of axial force and minor shear force, and the web welds are designed for major shear force. An example of the new checks carried out is shown in the picture below.
  • For CHS & SHS sections, an all around full profile weld is designed for the vector sum of axial, and major and minor shear forces. Note this effectively doubles the effective weld length for axial force compared with the previous release.

  • For RHS sections, flange welds (on faces A & C) continue to be designed for axial force, and web welds (on faces B & D) are designed for major shear force.

Design for Uplift

Newly introduced in Tekla Structural Designer 2022 - the scope of steel column base plate design checks is now further enhanced for the Eurocode regional code to consider uplift. The design method follows the provisions of BS EN 1993-1-8 and guidance of SCI P398.

Where previously a beyond scope status was issued, column base plates are now designed for uplift - both with and without shear. Such uplift is common for example for columns in portal frames and other low rise structures under horizontal loading.

This new design applies to base plates on I/H section columns with 2 rows of bolts in a doubly symmetric layout - hollow section columns are excluded.

Note that there are no concrete design checks for tension in first release such as cone or pull-out failure, and also no check for anchor plate punching under uplift.


The following new and enhanced checks are added for this condition, the pictures below showing examples of the design details for these:

  • Base Plate - Plate Bending for Tension - a new plate bending design check is added (under 'Base Plate - T-stub in tension'). Note the following and for further information see the expanded Help Topic Column base plate design to EC3.

    • The ‘Equivalent T-stub in tension’ method per BS EN 1993-1-8 is used for base plate bending design under axial tension.

    • For yield line patterns, reference is made to SCI P398 Table 5.3 of (for bolt rows outside column flanges), and Tables 2.2 to 2.4 (for bolt rows inside the flanges). For rows inside the flanges, the alpha factor is derived by an iterative process discussed in Appendix G of SCI P398.
  • Shear > Shear + Tension - a new shear + tension check is added to the shear check the details of which are included in the design details as shown in the picture below.
  • Welds > Tension force included - axial tension is now taken into account in Weld checks, with the weld resistance calculated using the simplified method of Clause 4.5.3.3 of BS EN 1993-1-8.
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