Reduced Loads in SEL – Linked Reactions |
  
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Reduced Loads in SEL – Linked Reactions |
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Once LL and LR reduction factors have been set and the beam calculation is launched, the factors will be applied to all applicable loads found on the beam. These loads will populate in the ENERCALC SEL interface with reduced magnitudes.
NOTE: Reduction factors will be applied to ALL LL or LR loads present on the beam. This reduction is applied uniformly to all three Revit load types (point, linear, and area), as well as “Load-Linked” reaction forces. Reduction is applied regardless of whether the forces are populated in the “Span Loads” or “Loads All Spans” tabs. The design professional is responsible for verifying that reduction of all loads is appropriate for the design.
Users should be aware that “Load-Linked” reaction forces produced by a calculation where LL reduction was used will NOT be stored in the Revit model with reduced magnitudes. This is because LL reduction is an element-specific code provision, and the permissible level of reduction will vary from one structural component to the next.
As a result, reactions are stored in the Revit model with an “unreduced” magnitude obtained by dividing the reduced LL or LR reactions by the applicable reduction factor. This process prevents “Load-Linking” reactions from being stored in the Revit model with a magnitude that reflects code provisions unique to only one specific element and allows loading in the Revit model to remain valid even when the LL reduction settings on various elements change over time.
As an example, consider the design scenario illustrated below. The floor framing layout uses long-span deck with a large spacing between floor beams, causing both the beam and its supporting girder to be individually eligible for LL reduction. The floor beam is designed first, and live load reduction is activated:
Following the design of the infill floor beam, the girder is designed next, but LL reduction on the girder is NOT activated. The girder calculation populates in ENERCALC SEL with unreduced reactions from the beam, demonstrating that the design of the girder is NOT inappropriately influenced by the reduction factor previously used to design the beam.
The girder design is then re-launched, this time with LL reduction activated. In this case, the girder tributary area differs significantly from the beam tributary area, corresponding to a different LL reduction factor.
When the girder calculation is launched, the unreduced beam LL reaction is detected and automatically reduced using the reduction factor computed for the girder calculation.
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