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Frame vs Sumo: Pad Footing Design workflow

When analysing a structure in Sumo or Frame, one or more bases and their respective load cases can be transferred to Pad Footing Design using the Design Links. The analysis type that’s performed in Sumo or Frame, and the loads considered play an important role in how loads are sent to Pad Footing Design. To illustrate the different possible outcomes, the following scenarios are considered:

Scenario 1: Performing a linear analysis in Frame or Sumo, considering Load cases and Load Combinations.

Figure 1: Linear: Sumo or Frame – Load cases and combinations

When load cases and combinations are considered, Pad Footing will receive the individual load cases as well as combinations including load factors.

Scenario 2: Performing a linear analysis in Frame or Sumo, considering Load Combinations only.

Figure 2: Linear: Sumo or Frame – Load combinations only

The Load combinations are received by Pad Footing with a load factor of 1. The loads have already been factored and the load doesn’t have to be factored again.

When preforming a second order analysis we can’t simply apply superposition to the load cases to determine the load combinations, since the second order effects are determined iteratively and depend on vertical and lateral loads.

Scenario 3: Performing a second order analysis in Frame, considering Load cases and Load Combinations.

Figure 3: Second order: Frame – Load cases and Load Combinations

A load factor is applied to the load cases. This load factor might be a strange value, because it is a factor determined internally and is the multiple which takes the load case loads to the load combination load.

Scenario 4: Performing a second order analysis in Frame, considering Load Combinations only.

Figure 4: Frame, considering Load Combinations only.

The loads have already been factored; the resultant reactions are used for design (with a load factor of 1).

Scenario 5: Performing a second order analysis in Sumo, considering Load cases and Load Combinations.

Figure 5: Sumo, considering Load cases and Load Combinations

If a second order analysis is done in Sumo, the load factors exported to Pad Footing are all equal to 1, that is the loads have already been factored in Sumo.

Scenario 5: Performing a second order analysis in Sumo, considering Load Combinations only.

Figure 6: Sumo, Second-order Load Combinations only

The loads have already been factored; the resultant reactions are used for design (with a load factor of 1).