Vertical Pier Cap [SIG]

For cases where columns need to be placed under the bearings, the vertical pier cap object can be utilized, as the pier column objects require pier cap objects to be defined.

The following screenshots can be used for further clarification of the use case for the vertical pier cap.

General

Location: Choose a support line to indicate the position of the pier cap.

Section Data: The section of the vertical pier cap can be specified.

• Section Length(Starts From Top): Input the distances for the defined section, starting from the top of the pier column. If the sections do not vary, one row is sufficient.

• Start Section: The location of the start section is calculated as the sum of all previously defined rows. If it is the first row, then the starting point is the top of the pier column.

• End Section: The position of the end section is determined by adding the distance defined in this row to the sum of all previously specified rows.

Slope Option[Alignment/Input]: If cross slope of the alignment at this station needs to be used as the slope of the pier cap,”Alignment” can be selected. To input a slope value in the next column, select 'Input'.

Slope: The transverse slope of the top of the pier cap can be adjusted using positive or negative values, which will rotate the section as demonstrated below.

Top Elevation Offset from Alignment: Specify the distance from the midpoint of the pier cap at the top to the PGL location, where 0 indicates that the midpoint of the pier cap is at the PGL location vertically. Generally, a value equivalent to the sum of the deck thickness, girder depth, bearing depth, and haunch depth is employed.

Transverse Offset: When 0 is entered, the midpoint of the pier cap (equal to half of the cap length) will be positioned at the PGL location. If a negative value is used, the pier cap will be offset in the left direction when looking up-station from the alignment, and if a positive value is used, it will be offset in the right direction when looking up-station from the alignment.

The positive direction of the Y-axis will be to the left when looking upstream along the PGL. However, based on the requests of engineers who have been using OpenBrIM for their bridge projects, positive transverse offset values will indicate the right-hand side when looking upstream along the PGL. This distinction should be taken into account when defining the location of bridge elements using transverse offset values (where positive transverse offset indicates the right side), as well as when making definitions related to FEM and loading (where positive Fy indicates the left side along the PGL).

Longitudinal Offset: If you intend to adjust the centerline of the pier cap in the longitudinal direction, use this offset value. For end bents, a value of typically half the section width can be helpful, as support lines are typically not defined at the centerline for end bents.

FEM

Generate FEM ?[Yes/No]: Setting the "Generate FEM" parameter to "No" can disable the analytical representation of the pier cap substructure.

Rigid Section: To connect the pier cap finite element to the bearing, the user needs to specify the properties of the rigid section. When bearings are longitudinally offset from the support line, rigid elements are automatically generated to link those bearings to the pier cap.

Additional Break Points List: Break points can be added to include additional nodes at various positions. By default, nodes are generated at the column and bearing locations.

Vertical Distance From Top of Section to Bottom of Bearing: Node locations are typically generated on the top of the cap section. However, in the case of an inverted T section, this behavior is not desired, and instead, rigid lines should be positioned on top of the bottom flange. To address this situation, the following parameter can be utilized. Mesh Size: The maximum distance between nodes in the elements local X-direction is specified using the mesh size.