- Automatically consider the stiffness effects of the Panel Zone where column members and girder members (horizontal elements connected to columns) of steel structures are connected. Panel Zone Effects are reflected in the beam elements. Column members are recognized as beam elements parallel to the GCS Z-axis and beam members are recognized as beam elements on the GCS X-Y plane.
From the main menu, select [Boundary] tab > [Advanced] group > [Panel Zone Effects]
Panel Zone Effects dialog box
Auto Calculate Panel Zone Offset Distances
Auto-calculate the panel zone based on the dimensions of the members and take them into account for stiffness calculations.
Offset Factor : Effective factor for the offset distances in panel zones
Output Position : Output position of element's internal forces
Panel Zone : Output of element's internal forces at the Panel Zone boundaries
Offset Position : Output of element's internal forces at the positions adjusted by the Offset Factor
Do not Calculate
Do not consider the panel zones.
The functionality of Panel Zone Effects is determined based on the output position. When the Output Position is set to "Offset Position," the consideration of element stiffness, self-weight and distributed loads, as well as the output location of member forces, are adjusted based on the Offset Factor (stiffness region correction coefficient). When the Output Position is set to "Panel Zone," only the element stiffness is adjusted based on the Offset Factor, similar to the case of Output Position as "Offset Position." The consideration of self-weight and distributed loads, as well as the determination of the output location of member forces, are fixed at the boundary positions of the Panel Zone (for beams, it is the location where the end of the beam and the face of the column meet; for columns, it is the location where the top and bottom faces of the column meet the beam).
Please note that when using the Panel Zone Effects feature, if the Output Position is set to "Offset Position" with an Offset Factor of 1.0, it is equivalent to setting the Output Position as "Panel Zone" with an Offset Factor of 1.0. Similarly, if the Output Position is set to "Offset Position" with an Offset Factor of 0.0, it is equivalent to not using the Panel Zone Effects feature.
When utilizing the Panel Zone Effects feature to automatically consider the stiffness region, the consideration of self-weight and distributed loads, as well as the output location of member forces, are determined based on the Output Position. Therefore, it is important to pay attention to the following points.
Calculation of Element Stiffness
When calculating the stiffness of an element, the length between the two nodes is used for axial stiffness and torsional stiffness. For shear stiffness and bending stiffness, the length adjusted by the stiffness region correction coefficient (L1 = L - ZF (Ri + Rj)) is used, regardless of the Output Position.
Here, L represents the length between the two nodes of the element.
Calculation of Distributed Load
If the Output Position is set to "Panel Zone," the distributed load acting within the stiffness region and between the nodes is considered as shear force only at the respective nodes. The distributed load acting on the remaining segments is considered by replacing it with shear force and moment.
If the Output Position is set to "Offset Position," the location adjusted by the Offset Factor (stiffness region correction coefficient) is used instead of the stiffness region of Output Position = Panel Zone.
Considered length for self-weight
The self-weights of column members are considered for the full distances between the end nodes irrespective of the use of Panel Zone Effects. For girder members, when Output Position = Panel Zone, the net distances excluding the panel zones (L1 = L - (Ri + Rj )) are used to calculate the self-weights. When Output Position = Offset Position, the offset distances reduced by the offset factor (L1 = L - ZF (Ri + Rj )) are used. In addition, the defined self-weights are considered in the analysis by converting into shear forces and moments similar to that for the distributed loads described above.
Output positions of member forces
If Output Position=Panel Zone, the member forces for columns and girders are additionally produced at the quarter points of the net lengths between the Panel Zones.
When Output Position = Offset Position in the case of girder members, the member forces at the quarter points are based on the member lengths adjusted by the offset factor. For example, Output Position = Panel Zone corresponds to the case where Output Position = Offset Position and Offset Factor =1.0. The member forces at these positions are also used in the Design functions.
Panel zone considering Beam End Release Condition
Panel Zone Effect are not considered at the points of beam end releases. (Refer to "Beam End Release")
Method of considering offset distances for each member type using Panel Zone Effects
The panel zones for each member type is considered by the following methods :
1. Column members
The length of a column member is the floor to floor height.
midas Civil assumes that the top flanges of beam members correspond to the story level. As such, the panel zones for column members need to be considered only at the tops of columns. (Refer to "Structure Type")
The panel zones for column members are determined by the directions and depths of the girder members connected to the column members. The panel zones for column members are separately calculated for moments about local y and z-directions.
When girder members are connected to a column in several directions, the panel zones for each direction are calculated by the following methods (Fig.1):
RCy : Panel zone for moment about the element's local y-axis at the top of a column member
RCz : Panel zone for moment about the element's local z-axis at the top of column member
BD : Depths of girder members connected to the column member
: Angle formed by the girder member and the local z-axis of the column member
The Panel zones for a column member in each direction are determined by the largest values among the panel zones in the directions of the girder members.
<Figure 1> Example of calculation of column panel zones
2. Girder members
The panel zones for girder members are determined by the Depth and Width of the column members at both ends. The calculation method is described below.
Equation for panel zone distance (Fig.2)
Depth : Section dimension of the column member in the element's local z-direction
Width : Section dimension of the column member in the element's local y-direction
: Angle formed by the girder member and the element's local z-axis of the column member
<Figure 2> Example of calculation of girder member panel zones