Working with Members

Dr. Frame2D provides various options for creating, selecting, removing, modifying, and displaying members, member properties, and member response to loading.

Creating Members

To add members to a structure, choose either of the member tools from the tool palette:

Clicking (and releasing) with the tool's cross hairs at the desired start point, joint, support, or member will anchor the beginning of the new member. Feedback will then be given indicating potential member geometry as the mouse moves:

In each of the examples shown above, the pinned-end member is being used, and grid snapping is on (holding down the control key allows one to locate points off the grid without having to change the grid snap option).

To complete the member creation process, click again at the desired ending point, joint, location, or member. (Note that the background grid is not considered when creating a new member end on an existing member.) The figure below shows several common results corresponding to the examples above:

It is worth noting that regardless of the tool used to create them, all members in Dr. Frame2D are represented internally as beam elements--the different tools are provided simply as a convenience for handling common end conditions.

Modifying Member End Conditions

Member end fixity can be modified quickly two different ways:

using the member tools: hold the control key while clicking near the center of an existing member to change both ends or near one end to change only that end. For example, if a rigid connection exists control clicking near that end of the member with the pinned-end member tool will change the end condition to pinned.
via the Member Info Inspector: simply choose the appropriate pop-up setting to change the member end conditions.

Selecting Members

Existing members can only be selected using the Select Tool ( ). They can be selected individually by simply clicking on the desired member (or the displaced representation of the member when displacements are turned on). Holding down the shift key allows one to accumulate selections in the usual way.

It is sometimes difficult to know precisely when the cursor is over a member. Watch the Feedback Pane while rolling the mouse over a member to know exactly when the cursor is over a member.

One can more rapidly select groups of members by dragging a selection rectangle as shown below. Members (and joints, loads, etc.) whose mid-point are included in the selection rectangle will be selected.

Members can be grouped using Edit>Group (cmd-G/Ctrl-G), after which a click on any individual member within the group will select the entire group. Conversely, Edit>Ungroup will ungroup selected members. It is also possible to select individual members within a group by alt/option-clicking.

Removing Members

Delete a member or set of members by selecting it/them and then using any of the following:

the Delete command in the Edit menu (ctrl/cmd-D)
the Backspace (Win) or Delete (Mac/Win) key

Remember that like most of Dr.Frame's operations, removed members can be restored via the Undo command.

Modifying Member Geometry

Modifying member geometry is accomplished by redefining the geometry of the associated joints. See the section on joints for details. (In short, just select and drag the relevant joints, or select a joint and enter numerical coordinates in the inspector pane for more precise arbitrary locating).

Defining and Modifying Member Properties

New members are created using current default properties. To set or modify the default properties, be sure no members are selected and choose the Default Member Properties… command in the Modeling menu. This will bring up the following dialog (except the End Conditions and Misfit controls will be disabled):

As can be seen, this table allows one to select cross section and material properties as desired, and these properties will become the defaults until they are again modified. One can enter cross section information using pre-defined data, or manually as indicated below:

Various section types are supported, and once basic geometric data are entered, cross section properties are calculated automatically. Custom sections can be created, named, and then recalled for convenient use with multiple members:

It is worth noting that a member's joints are numbered from lower-left ("End 1") to upper-right ("End 2").

Display Options for Members

There are various options for controlling how members are drawn, and for displaying useful information. These options are available via the Options>Member Display popup as shown:

Most of these commands are applied to all members regardless of selection, while certain others are applied to selected members only. Sample effects are illustrated below:


A frame and wall with Tension/Compression Coloring turned on. Axial force is depicted using shades of red for compression and shades of blue for tension. In this figure, wall stresses are displayed using shades of red corresponding to the in-plane maximum shear stress.	Individual members can have dimensioning enabled by selecting them and using the Show Lengths menu command.To globally toggle the dimension display, use the Show/Hide Dimensions commands in the View menu. This capability make it straightforward to create basic geometry views.

See Working with Plots for further information on displaying member response to load.

See the Capacity/Design section for more member information.

Getting Member Information Quickly

One can obtain a quick summary of member properties, lengths, and internal forces and moments by placing the cursor over the member in question (no clicking necessary), and looking in the feedback pane at the bottom of the window.

Rolling the mouse over a member on the main diagram brings up a summary of general member information:

Rolling the mouse over a member on an auxiliary diagram brings up a summary of displacements, rotations, and internal forces/moments at the point where the cursor is placed:

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Using Dr. Frame2D