Girder/Cross Frame Erection (Complete) [SIG]

In the typical design process of a steel I-girder bridge, the girders and cross frames are constructed in a single stage. If partial girder and cross frame erection is required, it is recommended to avoid using this component and instead navigate to "Girder Erection (Partial)" in the tree view.

General

Stage: During this stage, finite elements for girders and cross frames will be constructed and their self-weight will be applied concurrently.

Bridge: All girder and cross frame components of the selected bridge will be constructed at selected stage.

Splice Load [Ignore/Include]: If splice weight loads are to be included in the FEA, set the option to ‘Include’ for this parameter. If the option ‘Ignore’ is selected, the weight loads of the splices will be neglected.

Stiffener/Gusset Plate Load [Ignore/Include]: If the weight loads of the stiffeners or gusset plates are to be included in the FEA, select 'Include' for this parameter. If you need to neglect the weight loads of the stiffeners or gusset plates, select 'Ignore'.

Girder Self Weight Factor: The Girder Self-Weight Factor is a parameter used to adjust the contribution of a girder's own weight to the overall structural load calculations. This factor allows for the scaling or modification of the girder's self-weight in finite element analysis (FEA).

Cross Frame Fit

Fit Condition [No-Load Fit (NLF)/Steel Dead Load Fit (SDLF)/Total Dead Load Fit (TDLF)]: Selects the fit condition the cross-frames are detailed for (AASHTO 6.7.2 / C6.7.2, NSBA Skewed and Curved Steel I-Girder Bridge Fit) and automatically computes the resulting lack-of-fit locked-in forces. A conventional staged analysis corresponds to No-Load Fit — cross-frames activate stress-free. With SDLF or TDLF selected, each cross-frame member's lack-of-fit strain is computed per the AASHTO 6.2 definitions — from the target-load vertical deflections and the associated girder major-axis rotations at the connection work points, webs idealized plumb — and imposed at this stage. The locked-in cross-frame forces and girder flange lateral bending appear as a separate EL — Locked-in Force Effects result case: assign it to a free Load Case slot of each Limit State item with maximum and minimum factors of 1.00.

Total Dead Load Stage: Shown for TDLF only — the final dead-load stage whose plumb-web geometry the cross-frames are fabricated to fit. For SDLF no additional input is needed: the fit target is this stage's steel-erection-complete geometry.

Single analysis pass. The solver measures each member's lack-of-fit on the fit target stage's solved geometry and imposes it immediately in a "Locked-in Force Effects" substage that appears right after that stage in the results tree — no second analysis is needed. Expected behavior: negligible effects on straight non-skewed bridges; offsets the dead-load cross-frame forces on straight skewed bridges; additive on curved bridges. Girder cambers are unaffected. NSBA guidance: prefer SDLF or TDLF on skewed straight bridges (avoid NLF); prefer SDLF on curved bridges; do not specify TDLF for curved bridges (L/R > 0.03).