ETABS provides for the modeling of panel zones and rigid offsets. To demonstrate, the steel-frame system, shown below, is subjected to a 10-kip lateral load along its top level. Panel-zone and rigid-offset conditions are modified for comparison.

Model 1: Rigid zone factor = 0, No panel zone

Figure 1 - Model 1

Maximum deflection: ∆_x = 0.133in

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Model 2: Rigid zone factor = 1.0, No panel zone

Figure 2 - Model 2

Maximum deflection: ∆_x = 0.104in

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Model 3: Rigid zone factor = 0, Panel zone from column

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Figure 3 - Model 3

Maximum deflection: ∆_x = 0.152in

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Model 4: Rigid zone factor 1.0, Panel zone from column

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Figure 4 - Model 4

Maximum deflection: ∆_x = 0.128in

Model 4 utilizes both features by modeling fully rigid offsets at beam & columns while explicit panel zone assignments are based on column properties. Here, flexibility at joint locations is correct and accurate. We recommend using this approach because it is the most realistic, as indicated by response, in which deflection and moment are within the extreme bounds. 

Notes

• If the user-defined rigid-offset lengths option for Model 1 were set to (0,0), rather than default settings based on connectivity, results would be identical except that moment values would be reported at the end of members, and not at the face of columns and beams.

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