Overview of load patterns

Tekla Structural Designer
2020
Tekla Structural Designer

Overview of load patterns

Note: When you apply pattern loading to imposed loads, the factors of the loaded and unloaded spans are specific to the design code that you are using.

The basic steps of applying pattern loads

  1. Set individual imposed load cases to be patterned according to your needs.

    These load cases are referred to as fully loaded pattern load cases.

  2. Set the gravity combinations that contain imposed load cases to be patterned according to your needs.

    These gravity combinations are referred to as base case pattern combinations.

After load decomposition, the building analysis automatically sets up the pattern cases for concrete beams in Dir1 and Dir2 directions as follows:
  • 10 pattern cases for each pattern gravity combination

  • 5 pattern cases for beams along Dir1 and 5 for beams along Dir2

Note: By default, patterns are only applied to beam loads, and slab loads that have been decomposed on to beams. Loads applied to meshed slabs should be manually patterned using engineering judgement. For more information, see Update load patterns.

Pattern load cases

A pattern combination containing patterned imposed load cases results in 11 combinations: the base case combination, and 10 pattern combinations derived from the base combination.

If you later modify the building geometry, update load patterns to ensure the load patterns reflect the changes.
Note: Tekla Structural Designer contains a set of 10 pattern combinations associated with each fully loaded pattern combination. The pattern combinations are the same for beams and slabs.

The rules of applying load patterns to slabs and beams

Slab load patterning only applies where two-way slabs have been meshed in the solver model:
  • in FE chasedown analysis

  • in 3D analysis where two-way slabs are set as meshed

Therefore, the slab load pattern setting has no affect on:
  • one-way spanning slabs

  • two-way slabs not meshed in 3D analysis, as the slab loads are being decomposed to beams and walls prior to creation of the solver model

  • two-way slab in Grillage chasedown analysis, as the slab loads are being decomposed to beams and walls prior to creation of the solver model

Therefore, in 3D analysis and Grillage chasedown analysis:
  • When a beam is set to Full Load, it receives the full decomposed load from adjacent unmeshed two-way slabs, irrespective of whether the slabs themselves are set to Full Load or Min Load.

  • When a beam is set to Min Load, it receives the min decomposed load from adjacent unmeshed two-way slabs, irrespective of whether the slabs themselves are set to Full Load or Min Load.

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