Truss Family Enhancements

[SeanSpence]

The Truss Family is easy to use, but it lacks a bunch of features that structural engineers and designers need. Below are some enhancements that would make the family a lot more useful

More Web Member types.

Issue: When a truss is engineered it is almost always designed with more than one web member size. The members in the center are usually smaller than at the ends. The vertical web members are almost always different in size to the diagonal web members.

Suggestion: There needs to be an ability to create different sizes along the truss so that an economical design can be modeled easily. Currently there is only 1 web member size. 1 top chord size and 1 bottom chord size.

Currently the sizes of the individual web members can be changed once the truss is in the project. Unfortunately this is an instance only ability and does not reflect how trusses are used in building construction.

Truss Types.

Issue: Trusses are always defined as a type. There maybe 10 different types of trusses engineered with hundreds of those types used in a facility. Currently it seems the only way to create a type of truss with varying web members is to bring in a truss family, tab and select the individual web members and change the member size. The ability to change the size of individual web members is available once the truss family is in place but there is no way to have this change occur to the other types of trusses that are identical on the project. The current work around for this is to create a "Group" of the truss then copy it around to the different location where it will exist. While this approach gets the job done, using groups has several draw backs. Firstly using Groups in the numbers required to frame a building degrades the performance of the model substantially. Secondly once grouped beams and framing members attaching to the group no longer behave correctly, they dont attach as they would if the truss wasnt grouped. Thirdly groups seem to create export errors when using navis, the members dont always show with the correct family. 

Suggestion: Allow custom changes to be saved to the family as a type rather than an instance change.

Truss Depth

Issue: Trusses are always detailed with a truss height defined. Currently when using the truss family template the top and bottom chords are located by there center of gravity/Center "y" location. Hence the height of the truss varies depending on the size of the top and bottom chord members See below

As you can see, there is a WT bottom chord and a Wide Flange Top chord. each has different depths, while the center to center of these members is 10'-0" the Out to out size is different.

The only way to fix this is to look up the different sizes of the top and bottom chord and subtract half of their depth from the truss depth. While this works it is not ideal. The truss depth has to vary from truss type to truss type depending on the sizes used. when chord sizes vary by small fractions of an inch, truss depths become in accurate.Out to Out of truss is what is important when modeling, not analytical location to analytical location.

Suggestion: Allow the graphical location of the element being used as a top or bottom chord be defined as top or bottom. Currently only the analytical location can be defined.

Truss Gusset Web Connections

Issue: Truss use gusset plates at the connection of the web members to the top and bottom chords of the truss. These gussets can become very big and create coordination conflicts with other diciplines who need to route utilities through the truss space. There is currently no way to add additional members to the truss family to model these accurately or to create a no fly zone collission element where the truss connection is. Because of this, any design over LOD300 cannot use the OTB truss family as part of the model.

Solution: Allow connection components to be inserted into the truss

Truss top and bottom connection

Issue: Projects that use trusses normally have a truss top chord plan and a truss bottom chord plan. This is because trusses are normally in excess of 8'-0" deep. Currently you can only connect members such as purlins and bottom chord bracing to the bearing chord selected in the truss instance properties. (see below)

If additional members need to be attached they need to be assigned to a different level. these elements dont connect to the truss and as such, their symbolic offsets dont work creating graphical representation errors on plan. Because they dont attach, they also do not move with the element if trusses move during the building designs evolution.

Solution: allow framing members to attach to both the top and bottom chord of a truss

[dbroad]

Revit trusses are relatively inflexible for no apparent reason in these areas:

1. For roof trusses with sloped top chords, there is no easy way to set a standard top chord overhang and end cut.  Not all trusses are metal. The current implementation requires that members be unpinned and manually cleaned up. This requires additional reference planes and lots of extra editing time with the end result looking only marginally better.

2. Bearing:  The location line being in the center of the truss is reasonable wood trusses, such as scissors trusses have bottom chords that are trimmed at the ends to seat on the wall or shims are added. There's no easy way to set the bottom chord of a wood scissor truss so that the bottom surface of the bottom chord either sits on the outside core of a wood frame structure or is trimmed to create a seat cut. 

3. Medium detail:  In a medium detail configuration, trusses  are drawn in the most clunky manner. I'm embarrassed to use them in final architectural drawings.  Connections aren't apparent.  Members don't connect and are left cut square with only one point of each web member touching the chords. The top and bottom chords stop short.  If the members are unpinned, extended, and coped, the cope is an inflexible 1", which isn't correct for wood trusses. Once a truss' members are unpinned and coped, the truss becomes inflexible without resetting the edits.  It's high time for cope offset controls. Better yet, just have a check mark for wood truss style cleanup.

4. Truss to wall justification - add center of core justification:  Trusses only lock onto the center of wall justification. This makes sense only for single layer walls with no non-structural finish elements or for walls with  finish thicknesses symmetrical about the core centerline.  This is absurd. What's the point of having a wall core with structural elements if trusses can't align themselves with the core center?  If the non structural finish elements are asymmetrically laid out about the structural core, trusses end up aligned to the wrong place.  I can't see of any way to fine tune the alignments to make sense for wood framed walls.  If the vertical web is set to the same width as the stud, it ends up overlapping the sheathing plane (see image).

These deficiences make it diffcult or impossible to do good detailing for roof trusses. Revit's been around for a long time. It's past time to get these obvious design flaws fixed.

Impossible to justifyTruss eccentricies wrt wall core centerlines

[Tom_Kunsman]

Just curious, this does not appear on the Revit Roadmap, so what is the status of these ideas making it to the next release of Revit? 

[lionel.kai]

@Tom_Kunsman next Revit? I'd say slim to none. If we're lucky, it'll probably be another 2-3 years at least, but considering the fact that it's been over 4 years since the OP, and I'm sure Autodesk was aware of the limitations of Trusses long before that... 😞

[SeanSpence]

I wait patiently for an email asking for my assistance! 🙂

Until then.... 😞

[YarUnderoaker]

 SeanSpence you are the hero of future generations! Perhaps your grandchildren will be have the opportunity to use enhanced trusses 

PS: this is sad when  Revit can not be improved in different parallel ways at onetime and we must wait year by year for next feature.

[SeanSpence]

HAHA @YarUnderoaker I'm sure it wont be that long 🙂

But seriously, we have been dealing with this for so long. If they are developing a well thought out update to the trusses that not only addresses the revit issues but also allows for easy linking into their analysis with truss types etc. That would be better than a band-aid.

The factory doesn't comment on open forums about work in progress, so I don't expect a confirmation but a warm fuzzy teaser would be nice. especially since this is away from the main idea page.

@harlan_brumm you run the show over there 🙂 can you give us a warm fuzzy update?

[kimberly_fuhrman-jones]

In an effort to consolidate threads, we are updating this thread to Gathering Support. We are continuing to evaluate where this request falls into our roadmap and will provide an update when we have made a decision. 

We are in the process of improving and consolidating the Revit Ideas. This is by no means a downgrade...simply part of our cleanup efforts. Rest assured that your Idea and feedback is valuable to our teams, and that your Idea will continue to be reviewed. 

The Factory

[ericaPCFS5]

I agree with all of these issues!   My additional complaint is that you can't populate roof trusses like a beam system.  On large projects, it is so time consuming to adjust hundreds of trusses when the design changes that I don't even use roof trusses.  I use a 2x placeholder at the bearing height with a beam system, and use 2D elements in all of my details.  I have to ask the Architect (and my boss) for forgiveness almost every time because I don't have the trusses modeled correctly.

[jesseM225G]

I also agree with this!  After much experimentation we have come to the conclusion that the truss tool is not really usable.  Instead we tend to model custom families for roof trusses, which takes much longer than it should...

[a_kralkay]

I just started working with wood frame building design after years of working in Revit... It is kinda shocking how bad wood frame roof trusses are. Like pretty much not even worth using with all the hassle. It's clear that trying to use the same truss family as steel isn't working. The connections between members are completely different and you end up with a bunch of additional settings that not only make it more complicated but also far less intuitive.

[SeanSpence · Accepted solution]

As someone who only uses steel trusses, I always thought that they were designed for Wood, and that we were an afterthought. It's funny to hear that the wood truss people think they were for steel, and they were the afterthought. 

At any rate. it's high time something was done about them. Only 2600 people or more have clicked on this thread thinking there was a solution to their problems in here. I guess we need 10,000 views.

If you're just finding this, Adesk had me move this to the idea forum and break it up in 2016. If you can help by clicking these links and voting them up, that would be great. It's been quite a while since then, but we can only cross our fingers and hope for some love!

truss-family-enhancements-more-web-member-types

truss-family-enhancements-truss-types

truss-family-enhancements-truss-depth

truss-family-enhancements-truss-gusset-web-connections

truss-family-enhancements-truss-top-and-bottom-connection

truss-family-enhancements-z-offset-value

truss-family-enhancements-automatic-member-coping

[Tom_Kunsman]

ADSK mentioned (or at least the person who was overlooking this topic) that there was NOT going to be any changes to the truss tool as they did not see enough $$ for what it would cost them to implement these. It is sad when there were so many votes, and it seemed for a while that ADSK might actually implement them. Seeing as the trusses are not even on the Roadmap to me it doesn't matter if there are a million votes for this.

[SeanSpence]

We do multiple projects a year with trusses where the overall project cost is, or nears a Billion dollars. I hope that's not the case. We have been struggling for a long time with their crappy solution to a common structural problem.

[atahir]

This has been going on since 2016! Autodesk! Are you kidding me?

if this issue with this many complaints and requests were in Tekla it would have been done in a couple of months.

Autodesk wake up and please wake up your 40,000 employees! 

[SeanSpence]

Only 3700 people looking for the answer to this problem now. Thanks for the reply @atahir Don't forget to vote though! We need those likes to be ignored by autodesk in the place where it counts!

truss-family-enhancements-more-web-member-types

truss-family-enhancements-truss-types

truss-family-enhancements-truss-depth

truss-family-enhancements-truss-gusset-web-connections

truss-family-enhancements-truss-top-and-bottom-connection

truss-family-enhancements-z-offset-value

truss-family-enhancements-automatic-member-coping

@Anonymous Just tagging you here as a follow up. Perhaps you could bring this much needed fix to the attention of someone who can do something about it.

[Tom_Kunsman]

The somewhat sad thing is that I once had someone tell me that Autodesk felt it would cost too much money to update the tools versus the return enhancements that it would create.

The truss tools don't even show up in the Roadmap. And as someone suggested, maybe it is time to get involved with the Beta program to give a voice to some of the Ideas suggestions that have been around for ever.

[piotr_pysz]

Hi All, especially @SeanSpence - thank you for the feedback and for bringing this up. 

I have created a 'Truss enhancements' card on our Public Roadmap - you can find it in 'ON RADAR' tab.