View Full Version : How do you model a bridge?
2011-04-25, 04:54 PM
I am trying to do a simple massing of a bridge. It is not just arc, more of a spline, and it curves in plan view as well. I tried to loft a profile along a 3D spline, but the profile rotated and twisted along the spline. Here is a JPG if what I've got, But I did the bridge in Cad and imported it.
2011-04-26, 02:36 PM
Lofting a single profile along a spline will do that to you.. very annoying but to get around it this is what i do.
host points along the spline, or use the control points of the spline, on the point planes host the profile of the bridge. select all the profiles, create form. if you have a profile on each control point of the spline the path will be identical.
This is assuming you are using conceptual modeling.
2011-05-26, 04:46 PM
new to the forum, so be nice !!
on the same subject: i believe i can handle the horizontal and vertical alignment of a bridge, except for the cross slope (the slope required on the slab when turning so inertia wont get you flying out of the road)
appreciate it vmuch !!
I am testing version 12 .. thanks again
2011-05-26, 08:10 PM
In the conceptual mass editor, make a series of 2D profiles with the proper bank, select them all and create form.
2011-05-26, 08:41 PM
thank you, Revitaoist !!!
I will redo to see what I am missing.
I think that I am going to get a flat / even road / no slope for drainage, in others words...
I want to raise one side of the road / or bridge to provide 'cross slope' or slope to one side of bridge or road... and of course I am looking for something geometrically correct... not just for visualization purposes. (without using the bridge module)
I will try it again tonite and will post results tomorrow... appreciate it very much !!
2011-05-26, 08:50 PM
The bridge you posted is not straight. How did you provide the slope on the road part of it, to one side ??
or you just modeled a flat road ??
I am looking for a command that provides a 'TWIST' along the road... i know , hard to explain in words...I think I need an image to depicts what I need.
picture attached !! not quite there yet.. but will cont trying
2011-06-09, 01:44 AM
I believe you are talking about the "bank" of the road?
The key to this operation is to get all the profiles right before you 'create form'.
Create a 3D spline with several hosted points.
At each point, draw a 2D outline of the road section.
Put the base point of the profile at the center of the road on the bottom of the profile, and use that as rotate center when rotating.
Rotate each profile individually to show the proper bank.
Now create form.
Use more profiles with incremental rotations for a smoother model.
2011-06-09, 03:17 PM
thanks for following up Revitaoist !!
I am trying that.. but got busy on something else and lost track...but, i think I got to the point that I couldnt insert a profile at each hosted point (ignorance probably)... but now, per your post, it seems that i have to draw and redraw the same profile each time at each host point...
Now, (thx to you) that I know that I am on the right track, will try again and post back results.. be back !!
2011-10-20, 03:24 PM
thanks for following up Revitaoist !!
...it seems that i have to draw and redraw the same profile each time at each host point...
...copy & paste works almost as well as using a loaded profile ;)
2011-10-21, 03:56 AM
You can also create a parametric profile or adaptive component that can be adjusted at each station point.
2011-10-25, 03:41 PM
Thanks Dimitri and Tropi !!
I need to re-visit procedure and put suggestions to practice... doesnt seem simple tho
Thanks again !!
2011-10-25, 08:07 PM
I'm just getting into the conceptual massing tools myself, but it seems like a simple sweep is the way to start: one path, one profile. Then you can add as many profiles along the sweep and adjust them to create the banking or whatever else you want. Then you only make the number of profiles you need.
Note: I use a reference line as the "Spline Through Points" path so I could adjust it in plan after the fact. Oh, and it took me a bit to realize I had to make the profile on the outside of the curve. That might be obvious to others, but it stumped me for a minute.
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