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Saturday, 25 February 2017

Gare do Oriente - Revit Nested Repeaters - part 3

In previous posts I described how to use Revit adaptive components and repeaters to start creating a model of Santiago Calatrava's roof structure of the Gare do Oriente in Lisbon:
Part 1 - The rig for one structural column
Part 2 - Placing roof panels onto the rig

This time we will look at creating the structural elements to put on the rig.




Here is a youtube tutorial on creating the structural elements as an adaptive component, and placing the adaptive components to become a 'Repeater'

Steps

Here is a quick checklist of steps required:
  • Start new adaptive family
  • Place a point at the origin, plus two more points
  • Make the points adaptive
  • Join all three points with reference lines, ensuring that 3D snapping is ON
Add an arc between points 1 and 3;  the arc must be kept planar with the 3 points, so it needs to be hosted to a rig (or alternatively a plane - not shown here)
  • Place a hosted point midway along the line between points 1 and 3
  • Place a reference line from that hosted point to adaptive point 2
  • Place another hosted point on that new line
  • Place a reference arc by Start-End-Radius, snapping to adaptive points 1, 3 and then to the latest hosted point
Create a curved swept blend along the arc:
  • Place two more hosted points close to each end of the arc
 
  • Create a new profile family from a generic adaptive template (not a traditional profile family template)
  • It does not require an adaptive point
  • Draw a 2D profile closed shape on the level work plane - in this example a T-shape
  • Dimension it and make it parametric
 
  • Save and load into the first adaptive family
  • Place a profile component onto each of the hosted points on the arc
  • NB. The reason for hosting the profiles onto points that are themselves hosted on the arc is that it gives much better control:  The points have rotation parameters as well as parameters to control their distance along the arc - required to vary depending on the structural connections. Hosting the profiles directly on the arc would not give those controls.
  • Duplicate the type of the profile component closest to adaptive point 1
  • Make its dimensions larger
  • Select both profiles plus the reference arc 
  • Create form
  • It will generate a swept blend that tapers to a smaller size towards point 3 
  • NB. For more detail on this procedure, refer to my post on Adaptive swept blends
Create a simple extrusion family
  • Create a new family from a generic adaptive template
  • Place two points (one at the origin)
  • Make them adaptive
  • Place a reference line between the points 
  • Host two points close to each end
  • Associate their 'Segment or Chord Length' properties to parameters for offsets from ends
  • Make the reference planes of the points always visible
  • Set the Work Plane as the reference plane of one hosted point
  • Draw a profile for the extrusion - I just made it a simple circle
  • Give it dimensions and associate to parameters
  • Repeat the same profile on the other hosted point
  • Select both profiles and the reference line
  • Create Form
  • Save the family - I like to use a code to indicate it is adaptive and how many placement points
    eg:  AC 2pt Tube
  • load it into the first adaptive family
  • Place one of the new extrusion components between adaptive points 2 and 3
  • Associate its properties to parameters in the parent family as desired
  • Flex the adaptive points to check it is all working

 This structure now requires an additional placement point in a different plane to the rest
  • Add another point close to point 3
  • Make it adaptive (4)
  • Move it down in the Z direction
  • Link points 2 and 4 with a reference line (optional)
  • Link points 3 and 4 with a reference line (optional)
  • Place one of the tubular 2 point adaptive components between points 2 and 4 
  • Place another between points 3 and 4 
  • The structure family is now ready to use
  • Save it and load it into the rig family created in part 1 - The rig for one structural column

Assembling the structure on the Rig

  • On the rig, add a new hosted point onto the vertical reference line - this represents the springing point of the structure where it starts to curve out
  • Below this will be a rectangular extrusion, to be added later
  • This point will host the base of the structure adaptive components
  • Change its Measurement Type property to segment or chord length
  • Associate its segment/chord length to a parameter for Height of springing point
 
  • If you have the roof panels already in place on the rig (Step 2), it will probably be easier if you temporarily hide them before starting, to make snapping easier.
  • Place one of the support adaptive components, making sure to snap the 4 placement points onto the rig in the right order:
    1. Springing point
    2. Central valley hosted point on vertical line
    3. Divided path point on inner circle (orthogonally, along X axis from origin)
    4. Divided path point on outer circle, one division around anti-clockwise
Array a pattern around the circle using the Revit Repeater function:
  • If you select just the one structural element and repeat it, you get a straightforward radial pattern - this is not what we want (so, undo it)
 
  • We need to teach Revit how the array pattern should go - so you have to place a second structural component:
  •  Place another adaptive component 90 degrees around the circle in the same sequence
  • The first two placement points go onto hosted points that are already occupied by the first structural component - so it is vital that you snap to the host points, and not to end points or adaptive points on the component.
  • Watch the prompt in the bottom left corner of the screen before each point placement - the first two should be to Point of Reference points
  •  The second two should be onto Point of Divided path
  • Use this technique for every subsequent placement of adaptive points - it gets progressively more tricky as you go
  • Select the two adaptive structural components
  • Click on the Repeater icon
  • You should get the desired pattern if all adaptive points were hosted correctly.  
  • If not you may be able to rehost the points (if you can guess which one is wrong!) - or just delete the adaptive component and place it again
  • The next step is to place two more structural components in the reverse direction (clockwise)
  • You could try placing them to the correct hosts, but it is really difficult with all those elements in the way - so it is easier to temporarily hide the repeater first
  • You may find that when you hide the repeater, the nested tubular components around the top do not hide.  In which case, you need to select one, then right-click to select all instances and hide those too
  • Once placed, the two new structural components will fit in the gaps between the first repeater element
  • Some of the structural members will be in the same place as the original ones, so you may get a warning message about identical instances.  
  • If this is an issue (for scheduling etc), then you will need to go back into the adaptive structural component and give the common elements a visibility instance parameter - back in the rig family, you can then switch off the duplicate structural members on the two newly placed components.
  • Select the two new components and array them using the Repeat function
  • Now the basic structure should be complete

  • Try flexing the parameters for the rig dimensions to check that the structure moves with it.
  • If you have the roof panels already placed, make them visible again to check that it aligns correctly


Click below to proceed onwards:
Step 4  Adding Struts to the structure
Part 5 - Assembling the Array of Structural Columns

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