AUGIWorld Magazine - January/February 2008 - (Page 26) ing in the conventional Revit manner. This will allow you to specify the bar size and spacing. It also allows you to specify how the cage is tied off at the ends. Revit has done a nice job with reinforcing over the years, however, and there is another way. A company called Robobat has developed some extensions for Revit structure that allow real-time reinforcing solutions. You can get these extensions from www. robobat.com. Once in place, you simply select the system to be reinforced and run the extensions. A dialog shows up guiding you through specific reinforcing scenarios. Once the rebar is placed, it can be controlled through the typical Revit commands and properties. I love you, Robobat! Supporting members Did I mention that families are the driving force behind any bridge structure? If not, I should have. Depending on the composition of the bridge (steel, concrete, or a combination of the two), your family should be of the proper category. If your bridge is predominately steel, then you would use the Structural Framing – Beams and Braces.rft or the Structural Framing - Complex and Trusses.rft files. These will help you in terms of scheduling and also when it comes time for structural analysis. If your bridge is predominately concrete, you can use one of the foundation templates provided or you can simply create an in-place family. Creating an in-place family allows you to design aestheticaly without the constant worry of having multiple parameters which will accommodate every design situation. Of course you can do this, but I recommend using in-place horizontal arc that architectural railings become impossible to use. If an architectural railing is the only option, then the solution is to create post families as generic models and insert them in the model. They can then be copied into position. But this will be time consuming. This is Revit Structure, after all. We can place loads on a bridge the same as we place loads on a building. Yes the loads are different, but Revit Structure has the capability of creating any load type and load combination we need. We can analyze for live, seismic, gravity, lateral, uplift, or any combination that will arise. Once these loads are placed, they can then be sent to your favorite analysis program contained within the model. Once the actual analysis occurs, the model can then be imported back into Revit Structure and all of the members will be resized. New load cases can be created in either Revit or the analytical software. The load cases (if supported by the third-party package) will then show up in Revit as the model is transported back and forth. The thing I like about the way Revit handles this is the fact the only the data is pushed back and forth. You don’t need to physically insert the model at a specific point. It is that transfer of data that makes BIM usable. Eric Wing lives in Syracuse, New York. He has been teaching AutoCAD and Autodesk products for nine years. He has been in the construction and engineering field for 17 years. Eric is the AUGI Survey Manager and is president and founder of SLUG (Syracuse Local User Group). He has written articles for AUGIWorld magazine and writes a monthly column in AUGI HotNews. w w w. A U G I . c o m Analysis If the answer to that question is “no,” then it is time for an in-place family. Guardrails families for the purpose of “once in a lifetime” situations. I have seen many people wrestle with a complicated family. Then I ask, “Are you ever going to use this again?” 26 For guardrails, I usually create an inplace family. This in-place family consists of a solid sweep. The reason for this is because a bridge has a camber a well as a radial plan layout, resulting in a concave surface that makes it extremely difficult to simply lay out a railing. A solid sweep however, allows you to define a path in which to sweep the geometry. A solid extrusion is also a valid option. This has to be combined with solid voids to follow the profile of the bridge vertically and horizontally. In some situations this may be the only viable solution. Analytical planes and reinforcing can also be added because this is done as an in-place family. The last method is to simply add a railing. If your bridge has only a slight camber, this will be no problem. It is when we get into a large http://www.robobat.com http://www.robobat.com http://www.AUGI.com
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