How to Design Steel Roof Truss in STAAD 1

[zakmuh]

Hello everyone,

I'm new to structural analysis and design using STAAD Pro. I've been using staad for last 6 months or so. So much to learn eh! I'm somewhat okay with concrete but know nothing about steel, I mean in staad.

I'm trying to analyse and design this long span (30 metres) steel roof truss using staad. Managed to get zero errors and warnings in the analysis report but when it comes to CODE CHECK, members fail! I'm pretty sure that I've done something really wrong (the way members are connected, material choice etc).

I've attached .std file with this post. It's an open structure. Can someone please have a look and guide me to get the perfect analysis and design pointing out the mistakes I've done in staad model.

I'd also like to know how I can add vertical and diagnol members to an arch (staad wouldn't allow)

Thanks in advance

 

[SethGuthrie]

Node 68 is a roller in X and the members are all pretty much pinned so you get some large rotation of the cantilever structure east of node 68 about node 6. A member between node 6 and 93 might help, or a modified support. Besides that, some of the members fail but I don't see any other major problems. Setting the proper member unbraced length is often the most critical task for truss modeling.

 

[kieran1]

Just curious. Does no one design trusses by hand anymore?

Kieran

 

[JedClampett]

I design trusses by hand. It relaxes me.
There's such a thing as doing designs too fast. Anyway, by the time I model a truss in STAAD, debug my model and check the design by hand, it doesn't save that much time.

 

[SteelPE]

JedClampett, I agree, there is such a thing as doing a design too fast. Too many times I have rushed through a project at the request of a client only to have them change something and have to do a bunch of work over again. My old boss used to never worry about deadlines. His excuse would be the job would be done when it was done and that by the time it was done all of the changes would have already taken place.

 

[hokie66]

SteelPE,
I don't recall you ever working for me.

 

[zakmuh]

SethGuthrie.....Thanking you very much for your valuable comment mate. It's really helpfull for a beginner in STAAD/structural anaylsis + design, someone like me

And also thanking others for their views and opinion on this.

JedClampett....I agree with you mate. Hand calculations most of the time saves time and hassle free. Sit down, get the members sorted putting to a table format and there we go! All done and dusted eh lolz!!

More advice and help...much appreciated guys

 

[SethGuthrie]

Regarding the arch question, you can approximate it (pretty closely) with line segments that follow the desired curve.
Regarding tips in general, the Bentley Be Communities site has a Wiki and a Forum that are pretty popular.
wiki:

http://communities.bentley.com/prod...n__wiki/selectsupport-technotes-and-faqs.aspx

forum:

http://communities.bentley.com/products/structural/structural_analysis___design/f/5932.aspx

But when it comes to Eurocode specific issues I won't be much help.

 

[zakmuh]

Hi SethGuthrie. Thanks alot for the reply. Just a qucik question about RAM Structural System. I know few engineers usign RAM SS for analysis + design. Is it like STAAD or more advance (better) than STAAD? Can we use this software to design concrete beams. columns. slabs etc like in STAAD?

Thanks

 

[SethGuthrie]

Ram Structural System is set up for buildings. It can do a variety of structures, but multi-story steel and concrete buildings are the emphasis. It has some advanced methods for automatic load distribution, composite beam design, steel joist design, lateral load distribution and special seismic provisions to name a few features that separate it from the broader range of general finite element analysis programs. But for this thread and the discussion of an arched truss it's not the best option. A general program like Staad.pro or Ram Elements is better there.

 

[zakmuh]

Thank you very much

 

[ARS97]

There is absolutely no way that you can analyze a truss and perform a code-check manually (by hand) faster than what it takes an experienced Staadpro user (or similar) to model and check the truss with Staadpro (or similar). Don't get me wrong, I understand the necessity of being able to perform such a calculation manaully, but let's get real here.

 

[zakmuh]

ANDYSINES...I agree with you. When we have powerful softwares, why would we do it by hand eh!

I'm at the moment getting myself familiar with STAAD Pro and RAM Elements for analysis and design. I also want to get familiar with a good BIM software to work with STAAD and RAM. Which one(Revit, Tekla, RAM SS etc)you guys would recommend me?
A question re Staad..I'm confused with 'concrete design' application within staad. Do we necessarily have to use this application for concrete design or can we just use staad output file report to get the design details.
Thanks!

 

[SethGuthrie]

For STAAD users we tend to recommend ProSteel (aka ProStructures for BIM, though we also interface with AECOsim Building Designer, Tekla, and Revit via the Integrated Structural Modeling (ISM) workflow.

http://communities.bentley.com/prod...wiki/integrated-structural-modeling-home.aspx

The RC designer just gives you more options and controls over the basic concrete design.

 

[ARS97]

I use Staadpro exclusively, and our drafting department uses Tekla for certain applications. I have to admit.......I'm not sold on the integration of design software with BIM software just yet. There's too many wierd "quirks" and too much clean up required at this point. So far, it seems as if it's just faster to have 2 independent models (one with Staadpro, one with Tekla) and let each user have their own model. I'm sure this process will become more refined in the future, but it's not there yet.

 

[JedClampett]

I never said I could do it faster. A lot of us are not an "experienced Staadpro user". We're dabblers who have STAAD and use it when necessary. We've done a lot of trusses and prefer the loss of efficiency compared with the gain in control and feel of doing our own numbers. So to judge that there's no way I can do it faster than an experienced STAADPro user is the wrong measurement. It's whether I could do it faster myself.
And when you're done with your computer analysis, how do you document it? Do you print out every number? Every load case? The model? How many pages is that? How do your reviewers check your work? Show me a system of putting your work on the shelf (hard copy on a shelf, not a server) and recovering it 20 years from now, when STAAD is long gone, and I'll consider it.

 

[ARS97]

JedClampett - persoanlly, my calculations consist of a combination of the Staadpro report and Word/Excel documents that show the setup data (input and design parameters), design load calculations, connections, etc. The bulk of the analysis and code-check data is contained within the Staadpro report. In some cases, I have a hand calculation (in Word or Excel) that is used for spot-checking purposes to verify the Staadpro results. Yes, it's alot of pages and not as user friendly as a well organized hand calculation.....I can't dispute that. I've never had the priviledge of peer review in my career (12 years) since I've been the lone engineer (structural anyway) at every placed I've worked, but my in my opinion, my calc reports are easy to navigate and contain the data that is necessary for a review. I know what you're getting at though......nothing replaces the old-school manual method. However, after you match your results over & over again with what the computer is telling you, sooner or later you become comfortable in the output and you trust those results more.