Add Members (General)

While the Add Columns tools provide options to add only vertical members, the Add Members (General) tools allow for the creation of members with any orientation within the model space. Thus the Add Members (General) tools can be used to input beams, columns, rafters, vertical and horizontal bracing as well as members rotated on plan, elevation or generally.

The Add Members (General) menu now also includes tools for creating curved members. Curved members can be specified to be curved about either the member major or minor axis. The curve is specified on the member centreline and the curve is limited to a arc of a circle - the curve can be part of a circle, it is not possible to create elliptical or parabolic curves. The arc can be created at any orientation, but the member can only be curved in the major or minor axis, that is, members cannot be double curved.

Similar to the Add Columns menu, the Add Members (General) menu gives various options to control the section materiel, section type and size, member rotation, set the member attributes and automatically add members to viewing and/or design groups.

The Add Members (General) menu and tools can be accessed from the top menu bar by going to Create>Add Members (General). This can also be accessed using the shortcut keys Ctrl+M. The Add Members (General) option opens the Define Members panel on the right hand side of the screen. The Define Members menu is shown below.

When adding members, the Object Snaps can be used to assist in placing a member. Thus members can be drawn using grid line intersection, other member ends, or at specified distances from selected snap points. With the use of the snap points, distances and angles can be input using text inputs.

Member Section.

The member section to be added can be controlled by the member section tools. The section material can be and cross section type is controlled by a combination of the icons and drop downs at the top of the Define Members window. The icons give the following options:

Add a Steel Section:

To add a steel section, select the  icon. Once selected, the drop downs below the icons allow for the selection of the Section Type, Steel Grade and Section Size. The member beta angle orientation can be input in the text box. The layout of the steel drop downs is shown below.

Add a Concrete Section:-

To add a rectangular, square, round, L or Tee section, select the concrete icon.

Then click on the ‘Edit Concrete Section’ icon to open the area where the shape and size of the section can be defined. Save the section before positioning it in the frame.

The section size can be later amended using the Properties > Member Section Materials menu option.

Add a Timber Section:-

To add a rectangular, square or round section, select the timber icon.

Then click on the ‘Edit Timber Section’ icon to open the are where the shape and size of the section can be defined. The moduli, strength and service classes, etc can also be selected. Save the section before positioning it in the frame.

The section size, etc can be later amended using the Properties > Member Section Materials menu option.

In-Use:-

The In-Use option allows for the quick selection of a column section already in use in the model. Selecting the  icon, the drop down options now allow for the selection of any previously input member section.

The Define Section check box allows the define section options to be deactivated. In this case, a default 356x406 UC 634 S355 section is added.

Once members have been added to a model, they section properties can be edited through either the Properties>View Member Property Editor or the Properties>Member Section Materials functions.

Attributes

The attributes of the input members section can be controlled through the Attributes section of the Add Members menu. The available options are as shown below.

Note: The Stiff Deck option applies the old style rigid member style stiff deck. This is based on modifying the member minor axis properties to make the member rigid laterally. This approach is less accurate than the semi-rigid style stiff deck method and is not compatible with the Finite Element module.

Member Group Options

The member viewing and design group options allow a column to be created and automatically added to a viewing group, a design group or to both. The relevant group can be selected from the drop down, if any viewing or design groups have already been created. Additional groups can be added by clicking on the  icon and inputting a group name or title in the text input box.

Adding Members with Polyline Method

The polyline method allows for the continuous drawing of members, rather than having to define a member at a time. This tool is useful when defining a run of beams, for example along a grid line or around the perimeter.

1.Open the Define Member Editor

2.Click the Polyline Method button to enable polyline drawing

3.Click the graphical interface to start drawing your polyline

4.Click on the end points of the first member or run of members

5.The end point selected is automatically taken to be the start point of the next line of members to be added

6.Repeat adding members as required

7.When you have finished draw all your members, click the Polyline Method button again to disable this feature

Split physical member

The split physical member check box option determines how the software treats members when they are defined to start or finish within the length of another member, for example, when drawing a secondary beam between two primary beams. Selecting this option will split the physical member into sections to match the analytical members, rather than merge the segments.

Add Curved Member

Selecting the Add Curved Member check box expands the Define Members options. This expand menu section is shown below.

Placement method:

The placement method drop down controls the input method for defining the curve. There are three methods to define the curve.

1.Curve Height - this method requires the input of the start and finish points. These define a line between the start and end points from which the offset of the curve is defined from the mid point of the chord. Graphically, the cursor can be used to define a horizontal or vertical offset, the side the curve is drawn being controlled by the position of the mouse pointer. For a cured which is rotated relative to horizontal, the typed inputs can be used to defined the curve height at an angle from the horizontal. The axis of rotation is taken as the chord defined by the line between the start and end points.

2.Curve Centre + Start + End - this input method is based on the defining the curve by inputting the centre, start and end points. The required points can be selected graphically on screen using the mouse pointer and/or object snaps, or by typing in coordinates to overwrite the mouse pointer position. The orientation of the curve is governed by the right hand screw rule.

3.Between three points - since any three points uniquely defined a circle, this method allows for the definition of part of a circle by specifying the start and end points and then a point along the curve. The side the curve will be created is controlled by the side the curve mid point is selected on.

The inputs can be defined purely graphically using mouse and object snaps, or values can be over typed in the graphical inputs to manually enter values.

Beta Angle Curved in:

Members can only be curved in the the major or minor axis. This options controls the orientation of the member once it is created.

Analytical resolution:

The curved member design is based on a curved physical member with underlying analytical segments. The analytical resolution gives methods to control the resolution of the underlying analytic segments to make the analytic model coarser or finer as required. A finer resolution will introduce more analytic segments, but increase the number of underlying members and nodes which could impact on analysis times if the model contained a large number of curved members all created with a fine resolution. The curved members also require a minimum number of segments, with the default number set at 8 segments, so increasing the resolution above a certain point will not necessarily lead to a decrease in the number of analytical members. The resolution can be defined by one of three methods:

Chord Eccentricity % radius - this method uses the maximum distance of an analytic segment from the chord joining it's start and end points of the segment, and limits this to a percentage of the radius of the arc. Hence a smaller percentage leads to a larger number of segments.

Chord Eccentricity mm - This measures the maximum offset form the curve to the chord joining the start and end point of the analytic segment. This is similar to the chord radius, but is controlled as a distance rather than a percentage of the radius. Decreasing the distance will lead to a larger number of analytic segments.

Chord length m - this is the length of the chord joining the start and end points of the analytic segment itself. A shorter length leads to a larger number of analytic members.

In all cases, the input value is the target value rather than an absolute value to be used. This is because the number of analytic segments needs to be an integer value. For example, if the chord length does not divide the curved length, the software will use the nearest whole number of analytic segments.

When inputting a curved member additional information is displayed in the bottom bar underneath the graphics display. The text here indicates the input currently being asked for and the position of the mouse pointer or input value currently selected. The text also displayed the offset along an axis when using an object snap.

Cantilevers

For further information on modelling cantilevers and consideration of their deflections see the technical note on Cantilever Deflections.