New and enhanced automated loading

Tekla Structural Designer
Tekla Structural Designer

New and enhanced automated loading

Reflecting the worldwide use of Tekla Structural Designer, we have focused on making the program more flexible by both enhancing the automated loading features and extending their applicability to more regional codes. This makes Tekla Structural Designer 2022 more widely usable, especially for regions and countries for which the design codes may not be fully supported currently. These enhancements were first introduced in release 2021 SP3.

  • [TSD-9815] - Automated Minimum Lateral Loads

    Many design codes require consideration of a minimum lateral design load as a proportion of the gravity loads. A new feature automates the calculation and application of such loading - see below for more details.

  • [TSD-9613] - Use of the Seismic Wizard for other regional codes

    The existing Seismic Wizard variants can now be used to apply seismic loading for any regional code - see below for more details..

  • TSD-9707] - Use of the Snow Wizard for other regional codes

    Automated snow loading via the Snow Wizard has been available for the Eurocode and USA regional codes for some time. Some aspects of this are now made available to other regional codes - see below for more details.

  • [TSD-9619] - User-defined Imposed/ Live Load Reductions - Eurocode regional code

    The Imposed/live load reduction percentage can now be edited for the Eurocode regional code - see below for more details.

Automated Minimum Lateral Loads

A new option “Minimum Lateral Loads” (MLL) has been added in Model Settings immediately below the Loading group as shown in the picture below and is available for all regional codes.
  • In some regional codes MLL will be a minimum wind load case, in others a robustness check - some examples of the application of MLL are:

    • The USA code (ASCE 7-16 clause 1.4.2) recommends a value of 1% of total dead load as a minimum lateral design force.. For more on this see Minimum lateral loads (MLL) (ASCE 7)

    • Eurocode - the Singapore National Annex to EN 1991-1-4 Wind Actions requires that buildings should be capable of resisting, as a minimum, a design ultimate horizontal load equal to 1.5% of the characteristic dead weight of the structure. For more on this see Minimum lateral loads (MLL) (Eurocode)

    • British Standard (BS 5950) recommends a value of 1% of factored dead load as a minimum lateral load replacing wind load For more on this see Minimum lateral loads (MLL) (British Standards)

  • Settings
    • Default settings - these depend on regional code as follows:

      • For the USA, Singapore (Eurocode) and Malaysia (British Standards) MLL is switched on and set to Case A.

      • For other regional codes it is switched off i.e. set to None.

  • The MLL load is a percentage of gravity loading, with the gravity load to be considered configured as follows:

    • Gravity Loads - either Dead or Dead & Imposed can be selected.

    • Using Combination - either Unfactored or Factored Loads can be selected.

  • There are potentially two sets of loading that can be applied - Case A and Case B - each of which creates four loadcases acting on the structure in the +ve and -ve Building Directions.

    • When Case A or Case A & B are enabled, you specify the percentage loading for both directions (Dir 1 & Dir 2) as shown in the picture below.
  • Application
    • Load Cases - when Case A or Cases A & B are enabled, the appropriate “Min Lateral Load” load cases are automatically created and listed in the Loading dialog as shown below. These can be manually included in combinations or via the Combination Generator in a similar manner to Notional/ Equivalent Horizontal Loads (NL/EHL).
    • Load Combinations - When the MLL Model Setting option is enabled, additional “+MLL” combinations are included for all Gravity combinations listed on the second page of the Combination Generator as shown in the picture below. You can then select which of these you wish to include.
      • As you proceed through the Combination Generator, a new MLL page is now displayed - after the Generator’s NL/EHL page - as shown in the picture below. On this page you specify 1) in the drop list at the top the combination to be used for the MLLs and 2) in the table of combinations the applied load direction(s) for each active MLL combination.

      • The combination used for the MLL is set via a checkbox in the combinations main list in a new column headed “Min Lat Load” next to the existing “Camber” column, as shown in the picture below. Only Gravity Class combinations will be available for selection in this column. You can make the selection of the MLL combination via the Combination Generator as described above, or manually via this checkbox.
  • Review - The MLLs are automatically calculated and applied during analysis in the same manner as NL/EHL. They can also be reviewed graphically in the same manner in the Results View via the new “MLL” button in the Notional/ Seismic Loads group of the ribbon, as shown below. The Min Lateral Load cases are listed together with the other load cases in the load case/ combination selection drop list as are the MLL combinations.
    • The MLL cases are also listed in the Loading window of the Project Workspace where the total MLL applied can be seen as shown below.

Use of the Seismic Wizard for other regional codes

The Seismic Wizard can now be run for all regional codes, where previously it was available only for certain regional codes. The variant of the Seismic Wizard which is run is determined by the Seismic Loading code set in Model Settings > Design Codes. As shown in the picture below, all the currently available Seismic Loading code options are now listed for selection for all available regional codes.

  • This new feature means that it is now possible to select a seismic code that does not match the regional code, thus enabling seismic loading to be applied for regional codes that have no Seismic Loading code and hence no Seismic Wizard variant, such as British Standards.

  • Though it is less likely to be required, as part of this enhancement it is also now possible to do this for regional codes that do have a Seismic Wizard variant - such as the USA and Eurocode regional codes. Previously the Seismic Loading options available were fixed to those matching the regional code - for example ASCE 7 and UBC for the USA regional code.
  • In all cases the validity of setting a mismatched regional code and Seismic Code is at the discretion of and the responsibility of the engineer. The warning shown below is always issued when this is the case.
  • When seismic loads are generated for a mismatched regional code the following applies:

    • Generated seismic loads are based on the selected Seismic Loading Action Code.

    • Generated seismic load combinations are based on the Combinations Action Code (which is determined by the model regional code).

      • Thus no seismic combinations will be created by the Combination Generator for regional codes the Action Code of which does not consider seismic loading, such as British Standards. In such cases the engineer must manually create seismic combinations.

    • Seismic Drift checks are based on the selected Seismic Loading Action Code (NOT the Model regional code).

    • Conventional static design of members (to the selected Resistance Codes) will be performed for the results of the seismic combinations.

    • However, for regional codes that feature specific seismic member design checks for members of Seismic Force Resisting Systems - such as the USA regional code and seismic checks to AISC 341 and the seismic provisions of ACI 318 - these checks will NOT be performed in the case of mismatched seismic loading and regional code.

Use of the Snow Wizard for other regional codes

The Snow Wizard loading option is now available for the Australian, British Standards, and Indian regional codes. It is launched in the same manner as for the previously supported regional codes via the Snow Load > Snow Wizard command of the Load ribbon. It is used in a broadly similar manner, though its functionality for the new regional codes has some limitations in comparison to the existing variants for the USA and Eurocode regional codes as described below. For the basics of using the Snow Wizard see the Help topic Apply snow loading .
  • The functionality is the same for all the new regional codes; as shown above, you can automatically generate the following snow load cases using the Snow Wizard;

    • Balanced snow load (a single case)

    • Unbalanced snow load - up to four cases.

    • Drift snow load - up to four cases.

  • The generated Snow load cases are listed in the Loading dialog and can be included in combinations in the usual manner - either using the Combination Generator or manually - and appropriate combination factors are applied.

  • Application of snow loads in the generated snow load cases is not automatic. However the snow wizard load functions of Uniform Snow, Valley Snow and Local Drift Snow can be used to quickly and easily apply these types of load to Roof panels. These work in a broadly similar manner to the previously supported regional codes, the main difference being that the load values - such as maximum load values and drift length etc - are specified directly.

Imposed Load Reductions - User-defined reduction % values - Eurocode regional code

For the United Kingdom (Eurocode) and Malaysia (Eurocode) regional codes, the Imposed Load Reductions percentage values in Model Settings > Imposed Load Reduction can now be edited where previously they were fixed. This makes the program more flexible, allowing the user to adjust the reduction values should they need to.
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