Primary benefit of integral abutments is to offer joint-less bridges to improve the durability of the structure. The most common integral abutment type is the pile bent abutment. The connectivity with the abutments causes the structure to move as a whole also creating restraining moments at the top of abutments. This effect is addressed by integrating superstructure and substructure in the analysis.
Different states and provinces have different approaches to design integral abutments. The level of analysis performed varies from practically none to full bridge analysis including soil structure interaction. The continuity between the abutment and the superstructure is typically established after erection of girders. The implementation in LEAP Bridge incorporates the popular method of designing girders conservatively while accounting for restraint to abutments via superstructure connectivity. LEAP also uses the concept of user specified equivalent pile lengths in lieu of soil structure springs.
The integral abutment feature is only used for analyzing piers and abutments. RC-PIER workflow is the same as before. Users can import reactions from CONSPAN and CONBOX or generate them within RC-PIER. Piers and abutments are then analyzed for these loads as part of a full bridge 3D model. In other words, the integral abutment option restrains the tops of piers and abutments through the fully connected superstructure and other substructures. Without the integral abutment option, the piers and abutments are analyzed as frames with no restraints at the top.
There are no changes made to the superstructure analysis and design procedures. For example, in CONSPAN girders are not designed for the negative moments that may be caused by interaction with integral abutments. This is typically done to achieve conservative girder designs.
Note that the Integral Abutments option is available only through LEAP Bridge Enterprise, since the full bridge with all piers, abutments and superstructure needs to be modeled.