Bracing Configurations A Worked Example

The Pipe Rack in SITE-STRUCTURAL-AREA01 will be used in this worked example. This example demonstrates how to create a Pline rule, how to utilise bracing configurations, and how to the modifiy bracing gaps. The splitting of diagonal bracing sections around a horizontal beam is also demonstrated.

6.8.1 Create a Pline Rule

To assist the designer in creating bracing and modifying the bracing gap, a suitable user defined Pline Rule will be created.

Select Settings > Pick Filters > Plines… from the main menu to display the Pline Filter form and then click the Define Rule… button to display the Define Rules form. Enter the following in the appropriate textboxes:

Name: RHS Bracing

Rule: PKEY INSET (‘TOS’, ‘BOS’, ‘LEFT’, ‘RIGH’, ‘NAL’, ‘NAR’) Description: Rule for RHS Bracing

Click the Include button to create the User Defined Pline Rule and click the OK button on the Define

Rules form. The new rule is displayed on the Pline Filter form. Click the entry RHS Bracing to set it as the current Pline rule.

6.8.2 Create Bracing

Create a Subframe below FRMW ROW_K named ROW_K-BRACING and make it the CE. Select

Create >Sections > Bracing Configurations… from the main menu to display the Bracing form. Enter CE

in the Storage area textbox.

Click the Profile… button in the Section Data area of the form to display the Section Specification form.

Select British Standard from the Specification options list and Rect Hollow Sections from the Generic Type options list. Select a 150.0x100.0x5.0 profile, leave the three Pline Settings as NA.

Click the Apply button to set the bracing specification and dismiss the Section Specification form.

Leave the Bracing Plane at the default option of Derived by

Section.

Select 4. A/K Bracing(3), 3 picks from the Available Bracing

Configurations list and click the Apply button to display the A/K

Bracing(3), 3 picks form.

Click the / \ Bracing (K) radio button and enter 200 in the Gap A text box and 150 in the Gap B textbox. Click the Confirm checkbox to set confirmation on.

the beam at EL. (+) 104110 T.O.S. between ROWS 1 and 2 and column K2 at the bottom, in that order.

Click the Accept button to create the bracing. Create the K bracing on ROW K between ROWS 5 and 7 using the same gap values. Dismiss the A/K Bracing(3), 3picks form.

From the Bracing form select the Defined… option from the

Bracing Plane option list.

The Bracing Plane form will be displayed. The position and orientation of the bracing plane can be specified by entering co-ordinates and a plane direction in the form. Alternatively, graphical selections can be made of model elements using EDG picks.

Navigate to the Positioning Control toolbar. Set the Pick

Method to Pline and the Pick Type to Snap. Select the TOS Pline on the beam that spans between

ROWS 2 and 5.

On the Bracing Plane form select the Plane Fill/Unfill check box and set the Plane Direction to North.

Click the Apply button followed by the Dismiss button. In the Bracing form, select option 1. Cross Bracing from the

Available Bracing Configurations list and click the Apply button.

The Cross Bracing form will be displayed. Enter 200 in both the Gap A and Gap B textboxes and click the Confirm checkbox.

Create the cross bracing between ROWS 2 and 5 by graphically picking very near the bottom of column K2, then selecting just below the horizontal beam (at EL. (+) 104110) on column K5. Click the Accept button followed by the Dismiss button on the Cross Bracing form.

Create a list of the K bracing members on ROW K. Mirror copy the list to the ROW_J-BRACING SBFR. Connect the K bracing on ROW J to the appropriate beams and columns using the Connect > Connect option from the main menu.

Revert to the Derived by Section Bracing Plane option on the Bracing form. Create the knee bracing on

ROWS 1, 2, 5 and 7 using option 8, Knee Bracing(2). Remember to change the storage area for each ROW on the Bracing form.

6.8.3 Bracing Gaps

The bracing gap associated with the cross brace between ROW 2 and 5 will now be adjusted. Manipulate the 3D-view such that the bottom of column K5 and the intersecting cross brace can be clearly seen. Select Modify > Bracing Gap… from the main menu to

display the Brace Gaps form. Select option 4. Distance from start/end to Pline intersections from the Available Gapping

list and click the Apply button to display the Brace Gap(s) form. Click the Confirm checkbox to turn confirmation on. Click and hold down the left mouse button on the RHS bracing member to display the Plines. Move the pointer to select the Pline running along the bottom of the RHS.

When the cursor changes shape, release the mouse button. Click and hold down the left mouse button on the UB column to display the Plines.

Select the nearest Pline at the centre of the web of the UB, this will either be the NAL or NAR Pline. The Gap A textbox on the Brace Gap(s) form will display the current measured gap value. Enter 75 in the Gap A textbox and click the Accept button to adjust the gap.

Repeat this procedure with the other cross brace at the bottom of column K2. Adjust the bracing gap at the top of the two cross braces using option 2. Distance on picked Pline from a fixed point.

Adjust the bracing gaps for the K bracing on ROWS K and J to comply with the drawings using similar methods.

Make column K1 the CE. Select Position > Align Secondary Nodes from the main menu to re-align the SNOD elements after adjusting the bracing gaps. Repeat this for each section that has bracing attached.

Select Modify > Sections > Split… from the main menu to display the Split Steel form.

Select Graphical pick from the Add to list options list. Pick one of the the cross brace members on ROW K to be split then press the Escape key.

From the Define split-on frame, select Pick Section(s) to split on from the options list. Graphically pick the other cross brace member on ROW K then press the Escape key.

Click the Trimmed radio button then click the Split button. The Pipe Rack bracing should look like this: