By default, CIP RC/PT Girder analyzes the Full Width of the bridge, which is based upon the aggregate properties of the entire bridge cross-section along the bridge centerline. Selecting Optional Girder By Girder Analysis allows you to optionally analyze the structure based upon the properties defined along the centerlines of individual girders. Enter the number of girders to be analyzed in the Number of Girders field. Choosing Slab (or a T-Beam) Bridge simplifies the data entry for a rectangular cross-section and performs a full width analysis.