New Equipment Load Entities

Tekla Structural Designer
Tekla Structural Designer

New Equipment Load Entities

Tekla Structural Designer 2021 introduces Equipment Load Entities. These are similar in concept and operation to the recently added Line and Area Ancillaries, for more about which see the 2020 SP4 Release notes section New Line and Area Ancillaries Loading. They enable the definition of three dimensional objects for the purpose of load application for such items as retaining tanks, plant and machinery etc. While developed principally with industrial structures in mind, they may have wider application for tanks, plant etc acting on any type of structure. As shown in the picture below, since (like Ancillaries) they represent physical objects, they are applied via a new button added to the “Walls & Loading Objects” group of the Model tab of the Ribbon. They can be of three principal shapes; Cuboid, Cylinder (Vertical & Horizontal) and Sphere.

They are also fully considered and loaded by the New Open Structure Wind Loading - For detailed information about how loads are calculated and applied to them see the new Help Topic Open structure wind loads.

Key aspects of the new Equipment Loads are:

  • The Equipment entities do not form any part of the analysis model - only the loads they apply take part in the analysis and are fully considered in design.

  • Definition - after activating the Model ribbon command, you create an Equipment Load entity by clicking its “Support points” in turn, clicking twice on the final point, just like creating a panel as shown in the picture below. Any number of points forming any shape can be selected though, just as for panels, they must all lie in the same plane.
  • Prior to creating, select the Equipment type in the Properties Window and enter the required parameters (which default to zero) for its size, base position, z (vertical distance above support points plane), lateral offsets (if any), loads and load application option - either “At CoG” (center of gravity) or “At supports” . Just as for any physical entity, all these settings can be reviewed/ edited via the Properties Window after creation by selecting existing Equipment entities. Note the option to “Apply open structure wind loads” which defaults to on.

  • The support points for an existing Equipment entity can subsequently be manually adjusted just as you can the vertices of any panel; select the Equipment entity, click a support point (single click, not click-and-drag), move the cursor to another point and click again to move it there. Adjustment points are also added between each support point, enabling the addition of further support points, as shown in the picture above.

  • Support point load calculation and decomposition - the support points define a “panel” which is used to calculate (arithmetically) the support point loads by assuming it acts as a rigid body and the load is applied at the Equipment CoG. The load decomposition is potentially in two stages as for Ancillaries; in the first stage the calculated loads are applied to the support points, in the second phase these are decomposed - where necessary - again by whatever supports these. For example in the case of a supporting two-way slab - as shown in the picture below - this 2nd stage decomposition will be in a two-way manner to the members supporting the slab producing VDL’s and point loads etc as appropriate.

    • Note that the calculation of the support point loads for lateral loads (from Open Structure Wind Loads) accounts for the vertical offset of the centre of gravity (CoG) of the Equipment entity, producing “push/pull” point loads and thus an overturning moment on the supporting structure.

  • If you do not wish to use automatically calculated support point loads, you can override this by selecting Apply load = “At Supports” instead of the default “At CoG”. As shown in the picture below, you can then directly enter your own load values for each support point.
  • You can also manually apply additional point loads - as dead/imposed and in horizontal or vertical directions - to Equipment Entities using the new “Equipment” load option in the Structure Loads group of the Load tab of the Ribbon. The loads can be applied either to the Equipment CoG or Support points.

  • Load Cases - dedicated Equipment loadcases are automatically created and removed (just like for ancillaries) as Equipment entities are added/deleted and can be included in combinations in the usual manner.

An additional setting in Global/ Model Settings > Loading > General controls the load Type for the Equipment Operating Content and Testing Content loadcases which can be set to either Dead or Imposed (similar to pipework ancillaries).

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