Represent Joints

Although each connection has created a corresponding Secondary Joint element in the Design database (shown in the Design Explorer as SJOIs, owned by SNODs), these do not yet have any geometry associated with them and are not therefore shown in the 3D graphical view. In order to represent them properly, a catalogue specification must be associated with each joint (in the same way that each section profile is defined by an associated catalogue specification).

Joints have a number of attributes whose settings allow you to position and orientate them and to modify the ends of sections connected to them. The most important of these attributes are looked at here. The key to success lies in the optimum design of the joint as defined in the catalogue, which is a specialized field beyond the scope of this user guide.

For the purposes of this user guide, these topics illustrate the main features:

A Shelf Angle Joint as defined in the Catalogue

(only the Neutral Axis pline is shown for clarity).

Position and Orientation of a Secondary Joint Relative to a Secondary Node

Connect a Joint to the Start of an Attached Section

How the origin plane of the Joint is set with reference to the Owning Section (via the POSL attribute), while its position within the constraints of that plane is set with reference to the Attached Section (by aligning the plines defined by the JLINs of both Joint and Section). That is, with reference to the orientation of the diagram, to move the Joint horizontally change its POSL and vertically change its JLIN. Both the Section and the Joint can be rotated independently by changing their BANGs (the Section rotates about its NA, the Joint about its OPDI).

How the Section End Configuration depends on the Joint to which it is attached

(a wedge-shaped Joint is used to demonstrate the principles).

For the purposes of this user guide, this section shows you how to add some simple bolted flanges where the beams are attached to the columns. The joint elements (SJOIs in the Design Explorer) already exist as a result of connecting the sections together.

To define each joint’s geometry:

1. Set a pointer to the joint specification in the catalogue.

   

2. From the main menu bar select Modify > Joints > Specification.

   You are prompted to ‘Identify end of section joint is connected to’.

3. Pick the end of any N-S beam (that is, any beam which abuts a column flange rather than a web) where you want to insert a bolted joint.

   A Joint Specification window is displayed for the joint to which the picked section end is attached.

   Note: You can apply a Joint Specification to the connected end of a GENSEC element. Click CE to load the current element (only if the element is a FIXING) to the Joint Specification window.

   

4. The method of selection from the available joint specifications is the same as that used to select section profiles. In this case select Column Connections, Column Flange, 6M24_flange and leave all other form settings at their defaults.

5. Click Properties.

   A subsidiary Modify Properties window is displayed which allows you to specify some local dimensional data for the selected type of joint.

   

6. For this joint set Thickness of Plt, Dist from TOS, and Dist from BOS.

7. Click OK to close the Modify Properties window and Apply the Joint Specification window to complete the setting of the joint specification. (The geometry of most types of joint can be modified via appropriate entries in a window such as this. How the catalogue has been set up can affect this.)

To see a correct representation of the joint set up the graphical view so that it displays holes (negative volumes) as well as solid items (positive volumes).

To do this:

8. Select Settings > Graphic from the main menu bar.

   

9. On the Representation tab, select the Holes Drawn checkbox.

10. Click OK to apply the setting and close the window.

Zoom in close to the beam end to see what the joint looks like. The height and width of the endplate are set automatically from the dimensions of the beam and column, respectively, with adjustments to suit the values entered in the Define Properties window. If the joint dimensions in the catalogue are specified as design parameters whose values are derived from the attached and owning sections. The joint displayed as shown:

The attached beam has been shortened to accommodate the thickness of the plate and the bolt holes in the plate have generated corresponding holes in the column flanges.

The position of the joint relative to the profile of the column (its owning section) is determined by the joint’s position line. To see the effect of changing this:

11. From the main menu bar, select Modify > Joints > Position Line.

    

The displayed Position Line window shows the current setting as either BOS or TOS (depending at which end of the beam the joint is situated). Change this to the opposite setting (that is TOS or BOS). Select the Re-trim attached section checkbox, and click Apply. The joint and its attached section end move thus:

Reposition the joint correctly, then click Dismiss to discard any information and close the Position Line and Joint Specification windows.

Rather than set each joint specification explicitly, you can apply the specification for one joint to other joints. The facility is used to specify the joint at the other end of the beam which has just been viewed.

12. From the main menu bar select Modify > Joints > Joint Like > Maintain Pline.

    Note: You can copy/pick the joints at the end of a GENSEC element or a SCTN element.

    You are prompted to ‘Identify end of section to be copied like’.

13. Pick the same section end as picked previously.

14. When prompted to ‘Identify section end to be modified’, pick the other end of the same beam.

15. Press Escape for both of the next prompts.

Zoom in close to the second joint and notice how its geometry matches that of the first joint. The position line settings for the two joints are, however, set automatically to opposite flanges of the column (TOS for one, BOS for the other), to give the correct alignment.

Note: If the joints were ‘handed’, such as a shelf angle, you would also see that the second joint has been rotated automatically about its vertical axis to match the start/end directions of the section. The endplate does not show this, but if you select Query > Attributes from the main menu bar, you are able to see which attributes differ between the two joints. If you want to reverse an action, from the main tool bar click Edit > Undo.