Load Patterning

The load patterning algorithm takes a given load combination and creates a set of sub load combinations for it to check. For example, a load combination containing wind would not apply both pressure and suction at the same time, but instead apply all the loads with both pressure followed by all the loads with suction.

Mandatory Patterns

Wind and seismic both have mandatory load patterning that the user cannot disable.

Live Load Patterning

Live loads are patterned first by grouping them based on their span and by which side of the member the load is on. Specifically, the direction of the applied load are considered for point loads. And the sign of the applied moment are considered for point moments.

In the case of Uniaxial column design, the following patterns are checked for both front and back sides of the column.

• All loads

• All loads on the front face

• All loads on the back face

• Alternating front and back faces between supports.

In the case of Biaxial column design, the following patterns are checked for all four sides of the column.

• All loads

• All loads on the front face

• All loads on the back face

• Alternating front and back faces between supports

• All loads on the left face

• All loads on the right face

• Alternating left and right faces between supports

• All loads on the front and left faces

• All loads on the back and right faces

• Alternating front and left, back and right faces between supports

• All loads on the front and right faces

• All loads on the back and left faces

• Alternating front and right, back and left faces between supports

The above automated patterning does not always guarantee the critical case is identified. Point moments cause discontinuities in the moment curve and reverse the sign of the diagram instantaneously. There are situations where the standard patterning approach may not fully capture the most critical loading scenario. If there is concern about unaccounted load effects, users should manually adjust and verify load patterns as needed.

Example: Live Load Patterning for an Uniaxial Column

The following diagram illustrates a column with eight live loads: V1, V2, V3, V4, V5, V6, L1 and L2.

Open

The software currently applies LL patterning by checking the following load combinations:

• All Live loads

• V1 + V3 + V5 + L1

• V2 + V4 + V6 + L2

• V1 + V4 + V5 + L1

• V2 + V3 + V6 + L2

These patterns ensure that different load distributions are considered in the structural analysis, capturing various possible scenarios for applied loads.