Pier & Column Definitions Dialog Box

The Pier and Column Definitions dialog box allows you to define single or multicolumn piers (bents). CIP RC/PT Girder supports integral (i.e., diaphragm) and drop-cap piers consisting of one (1) to an unlimited number of vertical columns. To open this dialog box, click the Pier button on the Geometry tab.

The Pier Name or label associated with a defined pier is referenced in the Bridge Component Layout dialog box in order to place the pier at a stationing along the bridge. It is possible to have piers defined but not referenced in the Bridge Component Layout dialog box, thus permitting you to have a variety of different piers defined and selectively use them in the bridge in order to obtain the best solution. Typically, you define just a few piers using this dialog and then make reference to them at multiple locations along the bridge. Piers differing by only column lengths must be defined as separate pier definitions.

Typical Integral and Drop-cap piers or bents are shown below. Integral bents always have a connection type of Fix to the superstructure. The embedded diaphragm in an Integral pier is not automatically modeled and its stiffness and load can be included in the model by creating sections for it using the Cross Sections dialog box. The stiffness of the drop-cap is not included in the analysis model.

Typical Integral Bent

Typical Drop-Cap Bent

The distance from the CG of the section to the bottom of the soffit (i.e., Y-bottom) is automatically included in the analysis model. The distances from the bottom of the soffit to the CG of the bearings, the CG of the bearings to the top of cap, and the top of the cap to the CG of the cap are optionally included.

Adding Pier Definitions

The Add Pier Def. button adds a new pier without columns to the grid. Select the desired type of pier, e.g., integral or drop-cap, and then set the various parameters for the pier. Certain parameters will be disabled depending on the type of pier you selected. In order to place the defined pier at a stationing along the bridge using the Bridge Component Layout dialog box, you must reference the Pier Name or label associated with the defined pier.

Perform the following steps to add a pier definition:

Select one of the existing rows in the grid by clicking anywhere in its row. A blue arrow displays on the left side of the grid to mark the selection.
Click the Add Pier Def. button. This adds a pier after the selected definition.
Enter the parameters for the new pier definition. A definition for each parameter is available below.

Copying Pier Definitions

The Copy Pier Def. button copies the selected pier definition and places it immediately after the selected pier definition.

Perform the following steps to copy a pier definition:

In the grid, select the pier you want to copy by clicking anywhere in its row. A blue arrow displays on the left side of the grid to mark the selection.
Click the Copy Pier Def. button to duplicate the selected pier definition. This action also duplicates all of the defined parameters for the selected pier definition.

Definitions

The Delete Pier Def. button deletes the selected pier definition. Note that you will not be asked to confirm the delete and that this deletion cannot be undone.

Perform the following steps to delete a pier definition:

In the grid, select the pier definition you want to delete by clicking anywhere in its row. A blue arrow displays on the left side of the grid to mark the selection.
Click the Delete Pier Def. button to remove the selected pier definition.

Column Types

CIP RC/PT Girder includes several predefined, prismatic column types. Selecting a predefined column is one way to place typical types of columns at a pier. Once you have selected one of the predefined column types, you can set the various parameters depending on the type of column.

NOTE: These column types cannot be modified and will not show up in the Column Definition dialog box.

If a pier contains a prismatic column that is not one of the predefined column types or if it contains a nonprismatic column, you must create a user-defined column type by selecting the Column Types button to open the Column Definition dialog box. In this dialog box, you can add, edit, or delete a user-defined column type. Once you have defined the new column type, you can add it to any pier.

Adding Columns

The Add Column button adds a new column after the selected column to the selected pier definition.

Perform the following steps to add a column:

In the Pier Definitions grid, select the pier definition you want to add a column to by clicking anywhere in its row. A blue arrow displays on the left side of the grid to mark the selection.
In the Column Definitions grid, select one of the existing rows in the grid by clicking anywhere in its row. A blue arrow displays on the left side of the grid to mark the selection.
Click the Add Column button. This adds a new column after the selected column.
Enter the parameters for the new column. A definition for each parameter is available below.

Deleting Columns

The Delete Column button deletes the selected column from the list of columns for the selected pier definition. Note that you will not be asked to confirm the delete and that this deletion cannot be undone.

Perform the following steps to delete a column:

In the Pier Definitions grid, select the pier definition you want to delete a column from by clicking anywhere in its row. A blue arrow displays on the left side of the grid to mark the selection.
Select one of the existing rows in the Column Definitions grid by clicking anywhere in its row. A blue arrow displays on the left side of the grid to mark the selection.
Click the Delete Column button to remove the selected column.

Grid Definitions

Setting

Description

Pier Name

Enter a unique name for the pier definition. The Pier Name or label associated with a defined pier is referenced in the Bridge Component Layout dialog box in order to place the defined pier at a stationing along the bridge. Note that not all piers need to be referenced in the Bridge Component Layout dialog box, thus allowing you to define a variety of different piers and selectively use them to obtain the best solution. Typically, you define just a few piers using this dialog box and then reference them at multiple locations along the bridge.

Note: Piers that differ by column length only must be defined as separate pier definitions.

Type

Select either an integral or drop-cap pier from the drop-down list.

Setting	Description
Integral	This pier or bent type places the tops of the columns at the bottom of the soffit and the connection to the superstructure is always Fixed.
Drop-cap	This pier or bent type places the tops of the columns at the bottom of the drop-cap and allows to have release forces between the superstructure and substructure at the c.g of the support bearings. Note: If you select a drop-cap pier, you may also define the following dimensions: soffit-to-bearing, bearing-to-cap, and the cap height.

Soffit-to-Bearing

(Drop-cap piers only.) Enter the vertical distance from the bottom of the soffit to the center of gravity of the bearings.

Bearing-to-Cap

(Drop-cap piers only.) Enter the vertical distance from the center of gravity of the bearings to the top of the cap.

Cap Height

(Drop-cap piers only.) Enter the total depth of the cap at the centerline. For nonprismatic or stepped caps, select a representative value for the cap height.

Column Definitions

Setting

Description

Col

This noneditable field lists the column number. Column numbers are measured from left to right, looking ahead on station.

Space

Enter the distance from the current column to the next one. This distance is measured in the plane of the bent, sometimes referred to as a "skewed" distance or measurement. Note that the last column will not have a space and this field will be disabled.

Len

Enter the length of the column from the bottom of the cap (or soffit) to the point of support.

Column Type

Select the type of column from the drop-down list. This list also includes any user-defined column types added in the Column Definition dialog box.

Setting	Description
Circular	This places a circular column of diameter "H".
Rectangular	This places a rectangular column with sides "H" and "V", where H is measured along the plane of the bent.
Rect-Fillet	This places a rectangular column with rounded corners of radius "R".
Rect-Chamfer	This places a rectangular column with chamfered corners of dimension "C".
Rect-Bevel	This places a rectangular column with beveled corners with dimensions "X" and "Y".

Columns

All user-defined column types will appear in the drop-down list after the five standard column types. Select one of the user-defined column types to place it in a pier.

Setting	Description
H	Enter the column's section width (or diameter).
V	Enter the column's section depth.
R, C, or X:	Enter the column's fillet radius, chamfer, or bevel-X dimensions.
Y	Enter the column's bevel-Y dimensions.

Support

Using the drop-down list, select the support requirements at the bottom of the column.

Setting	Description
Fix	This support condition fixes the bottom of the column for translation and rotation.
Pin	This support condition fixes the bottom of the column for translation but releases the longitudinal and transverse moments; torsion in the column is not released.
Spring	Selecting a spring support opens the Connector Spring Stiffness dialog box allowing you to define translational and rotational springs for the bottom of the column.

Material

Define the concrete material properties for each column using the Concrete Material dialog box.

IzzUsage

Select moment of inertia for the column (Gross or Effective) as defined in Column Definition dialog box.

Technical Discussion

The Pier and Column Definitions dialog box allows you to define single or multicolumn piers (bents). A pier definition represents a physical pier that is usually placed somewhere along the bridge although it is not necessary to locate any of the defined piers. If CIP RC/PT Girder does not find a match to a pier with the Ref. Name attribute on a component in the Bridge Component Layout dialog box, then it generates a continuous beam model (for that pier location) using the specified component connection as the connection between the beam (superstructure) and the boundary.

Columns within piers are vertical and are fixed at their tops. You may specify different bottom end conditions using the Support parameter. The connection between the tops of columns for both integral and drop-cap piers is infinitely stiff. Each column may have different flexible lengths and each column can have its own material properties as defined in the Concrete Material dialog box.

The analysis model generated for integral piers places the tops of columns (and, hence, the location of any force release between the superstructure and the pier) at a distance Y-bottom from the superstructure, where Y-bottom equals the distance from the center of gravity of the superstructure cross section to the extreme bottom fiber.

The analysis model generated for drop-cap piers places the tops of columns at a distance (Y-bottom + Soffit-to-Bearing + Bearing-to-Cap + Cap Height) from the superstructure. Any specified force release is applied at a distance (Y-bottom + Soffit-to-Bearing) from the superstructure. You can specify the dimension parameters for a drop-cap pier as zero (0) if you do not want to include the distances in analysis model. However, there is no program option to ignore using Y-bottom.

The columns in the substructure are modeled as space-frame bending elements (6 degrees-of-freedom per node), which are then statically condensed down to a single point of connection at the location where the pier attaches to the bottom of the superstructure connection. Therefore, the effects of skewed multicolumn bents and foundation spring constants (which are oriented in the coordinate system of the pier) are accounted for in the modified plane-frame superstructure model.