Sunday, April 22, 2012

BREAKING UP IS HARD TO DO

It usually takes me at least a year to chatch up with David Light, so no surprise that this is my first serious venture into the "Parts" feature first introduced in Revit 2012.  The task in hand was to study the relationships between RC frame, blockwork infill and insulated render system in a building with stepped recesses running vertically up the facade to unify groups of windows.


The wall system tool succeeds  quite well at representing the wrapping of layers at window reveals.  Looking more closely though, it works better in plan than in section.  The recesses are formed using a wall-based family containing just voids.  It's a simple way to cut niches and recessed into walls.  Sometimes I also embed detail components in the family to better represent head & sill conditions.
Where things sometimes go wrong with multi-layer walls cut by various families is at the "join geometry" stage. 


Almost all our work involves in-situ RC frames with blockwork infill.  Wherever sections are cut to clean up the intersections between slabs, walls & beams.  It works fine most of the time, but occasionally the complexity of the layer wrapping seems to get Revit to handle, and some strange random effects result. Often the outer layer of render material displaces the blockwork core and fills the wall up to the centre line. (see image above)



Returning to the task in hand, my first attempt was all done by breaking floors & walls down into parts (effectively separate layers) and then splitting the parts with curvy lines and hiding elements in the view to create a cutaway effect.  I came up with quite a useful image in the end using realistic style to express the different materials.  But the very act of creating parts destroys the wrapping of layers at window reveals.  So all the image looks good at first glance, it doesnt actually succeed in clarifying how the different materials fit together at the corners of the recesses.



So I started again and this time used good old in-place massing to model the wall elements in the critical area.  Having fallen for the curvy line cuts of the first attempt I decided to simulate this with a void cut based on a spline.



This method gave me more controll in modelling the wall layers and cutting them back to reveal construction.  But for the floor the parts method was the simplest way to peel back the screed & tiles.  As you would expect, it's possible to copy the sketch to the clipboard and past it back in when dividing the next layer down.


So while this is not really the core functionality of the parts tool, there is potential for creating diagrams that can be useful during design development, and also as as more visually rich ways to communicate with contractors.

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