Boundary conditions for bars

Which internal forces can be transferred (or which rigidity a connection) between two bars has, is determined using this button .
The following dialogue appears:

You see quick buttons (see further) and two columns to define the boundary conditions at the start and end point of bar.

• Start point = point with the smallest X-coordinate
  • If X-coordinates are the same, it’s the point with the smallest Y-coordinate
    • If Y-coordinates are the same, it’s the point with the smallest Z-coordinate
• End point = the other point

This dialog can contain padlocks depending on the properties of the elements you have selected. Read all about the padlocks in this article.

Quick buttons

The meaning of the quick buttons is as follows:

• : tie rod
  A bar in which only axial tension can be transferred. The use of tie rods always results in an iterative calculation due to their non-linear behaviour.
  The quick buttons for tie rods sometimes give iterations problems in the elastic analysis. The solution is then to model the tie rods using a function instead of using the quick buttons.
  
  A tie rod is not the same as a cable (like a clothes line). A cable cannot be modelled in Diamonds (more info).
  
  The counter part of a tie rod is a compression bar.
• : hinged bar
  At both bar ends My’ and Mz’ cannot be transferred. All other forces can be transferred.
• : hinge at the start of the bar
  At the start point of the bar My’ and Mz’ cannot be transferred. All other forces can be transferred.
• : hinge at the end of the bar
  At the end point of the bar My’ and Mz’ cannot be transferred. All other forces can be transferred.
• : clear all hings
  At both bar ends, all internal forces can be transferred

Whenever you select a quickbutton, the relevant options will be turn on/off in the middle of the dialog.

Instead of using the quick buttons, you can also set the relevant internal forces free, fixed, on a value or use a function.

Haunch

The last option allows you to apply a lower (z’ < 0) or upper (z’ > 0) haunch to each bar end. A haunch is characterized by length and height.
By applying a haunch, you locally increase the profile’s resistance and rigidity. The stresses calculated by Diamonds will decrease because of the increased profile height. The steel verification also takes into consideration the variable cross-section. The haunch also influences the distribution of moments because the variable rigidity is also included in the global rigidity matrix.
The haunch will also be be taken into account when the connection is detailed in PowerConnect. And conversely, these dimensions will be fulfilled when a haunch is added to the connection in PowerConnect.