This feature allows you to design hammerhead piers. Substructure simplifies the structural model of a hammerhead pier to two perpendicular lines, representing the centerline of the cap and column. Thus, the simplified structural model of a hammerhead looks like a T-shape. If there is a void in the hammerhead, the same structural model is applied, but the reduced section area and stiffness of the members is used to model the void. Note if a large opening is introduced, the T-shape model may produce inaccurate results. In this case, it is recommended to use the strut-and-tie model (STM).

After the structural analysis is performed, moments and forces at the sections for the cap or hammerhead are used in the design. If there is an opening, the beam design will provide the results for the segment between end of the cap and face of the opening. The section between the faces of the opening is not considered in the design and the user should check these sections by other methods. Column design will be based on the section moments and axial force. A reduced section property will be used if an opening exists. For such hammerhead columns with void/opening, the program designs the column sides as a single column and not as two separate columns.

Multiple column piers are the piers which support AASHTO Type girders. The connection between superstructure and substructure is such that only loads are transferred without any moment transfer to the substructure.

Multi-column pier uses the conventional frame analysis. The centerline of each component is used in the structural model. The structural model is composed of members and nodes. The proper section geometry, moment of inertia, and material properties are defined for the members. The bottom of the column is fixed. However, Substructure allows the option to add a spring in the vertical direction to simulate the settlement of the pier structure.

Multi-column designs are performed for cap, column, and footing individually. Note that you can design hammerhead piers by selecting the pier type as multi-column. In this case, you need to provide a single column.

Single or multiple column pier in which the superstructure is monolithic with the pier. In such pier, moment from the superstructure is also transferred to substructure along with vertical loads. Integral cap or any other cap shape can be used for integral piers. For integral cap (box type superstructures), user may specify box top and bottom slab as flanges for the cap beam.

For integral piers, program allows same number of girders on each side.