Optional Girder Analysis
CIP RC/PT Girder provides the designer with an option to perform a "Girder Analysis." This option assists in calculating plane frame modeling data based upon the geometries along the centerlines of individual girders. This option is intended to provide an easy way to address modeling issues arising from box girder bridges being constructed on curves, or having support skews, or both. When these conditions exist the support-to-support (span) distances, substructure stiffness, PT layout can all vary along the centerline of individual girders. The designer will need to determine appropriate span distances, substructure stiffness, post-tensioning (PT) layout, etc for analysis purposes. Because a plane frame analysis method is being used for analysis, the designer must define the most appropriate frame model for analysis. Many times this requires multiple models and analyses. CIP RC/PT Girder's Girder Analysis option addresses this need by automatically computing the modeling data with respect to individual girders. This allows the designer to focus on the effects that the varying conditions have on design solutions. It must be emphasized that the Girder Analysis option does not perform a three-dimensional analysis. Following are the assumptions used by CIP RC/PT Girder for Girder Analysis.
Post-tensioning forces
- Live Load distributed by using AASHTO distribution factors as appropriate (see discussions on Live Load Distribution).
- Aggregation from individual girders to Full Section assumes that all elements entered into individual girders are added directly to the Full Section:
- Load Intensity (point and distributed loads)
CIP RC/PT Girder automatically performs this distribution between the Full Section and the individual girders.