The wall pier element internal forces are similar to the frame element internal forces. They are:
P, the axial force
V2, the shear force in the 1-2 plane
V3, the shear force in the 1-3 plane
T, the axial torque
M2, the bending moment in the 1-3 plane (about the 2-axis)
M3, the bending moment in the 1-2 plane (about the 3-axis)
The positive directions of these forces are exactly the same as those described for the frame element.
These internal forces and moments are present at every cross section along the height of the wall pier element. They are reported only at the ends (top and bottom) of the pier element. The pier internal forces and moments are reported in the pier element local coordinate system.
Wall Pier Local Axes for a Two-Dimensional Pier
Typically a wall pier is made up of one or more wall-type area objects or a combination of one or more wall-type area objects and one or more column-type line objects. The local axes of these two-dimensional wall piers are defined as follows:
The local 1 axis extends from the bottom of the pier to the top of the pier. The positive local 1 axis is in the same direction as the positive global Z-axis. The positive local 1-axis points from the i-end of the pier to the j-end of the pier.
The local 1-2 plane is in the plane of the two-dimensional wall pier. The positive local axis 2 is horizontal and it has a positive projection on the global X-axis, or if the plane of the pier is oriented parallel to the global Y-Z plane, axis 2 is in the same direction as the positive global Y-axis.
The local 3 axis is horizontal and perpendicular to the plane of the pier. The direction of the positive local 3 axis is determined from the right-hand rule.
In the special case where a wall pier is made up of a single column-type frame element, the local axes of the pier are the same as those of the frame element.
If a wall pier is made up of two or more column-type frame elements, but no area objects, the local axes of the pier are the same as those of the first defined frame element. To confirm the local axes orientation in this unusual case, view them graphically using the View menu > Set Display Options command.
Wall Pier Local Axes for a Three-Dimensional Pier
In a three-dimensional wall pier, the local axes are defined as follows:
The local 1 axis extends from the bottom of the pier to the top of the pier. The positive local 1 axis is in the same direction as the positive global Z-axis.
The local 2-axis is parallel to the longest leg of the wall. The positive local 2 axis has a positive projection on the global X-axis or if the 2-axis is parallel to the global Y-axis then the positive 2-axis is in the same direction as the positive Y-axis.
The direction of the positive local 3 axis is determined by applying the right hand rule.
See also: