RE: TWO STORIES BUILDING 6

[mronlinetutor]

I am trying out Skyciv.com. It is a student version. The building should be a simple two stories 2X6 roof 16" o.c., 2X6 16" o.c. 2nd floor and 2X8 16" o.c. main floor made of wood. But Skyciv.com can only do metal buildings for optimal design. So I let the program choose the best HS section for the job. Tell me if the building is safe.

disclaimer: all calculations and comments must be checked by senior engineers before they are taken to be acceptable.

 

[SWComposites]

Seems the correct question to ask is "Does the design meet applicable Code requirements". "Safe" is not measurable.

 

[mronlinetutor]

The program provides Canadian, American, British, and Indian codes. The codes are embedded. I only need to select the code. In this case, I use CSA S16. The program does the checking and design.

disclaimer: all calculations and comments must be checked by senior engineers before they are taken to be acceptable.

 

[Celt83]

"I need to design a wood structure"

"I found this software and modeled a steel structure"

"Is it safe?"

NO!

This is absolute garbage in garbage out, you seem to have no idea what you are doing.

 

[Eng16080]

I haven't used Skyciv software, but based on a few minutes looking at your report:
[ol 1]
[li]It appears that the ends of all your members are fully fixed. This isn't realistic, especially for a wood structure. Wood members are typically idealized as pinned, meaning that the ends are free to rotate. Think of a simply supported beam.[/li]
[li]Similar to the member, it appears all of your supports are also fully fixed. In most cases this is not recommended.[/li]
[li]It appears your load combinations only account for dead and seismic loads. A real world building needs to be designed for live, wind, snow, and possibly other load types. For almost any building, the floor framing will be controlled by dead and live loads. In my geographic location, it's usually snow load which governs the roof design.[/li]
[/ol]

In general, your current model should be updated per the above. At that point, you can possibly use it to determine member and support loads, which can then be used to design the wood members by hand and/or with other software.

Overall, when using software, especially for the first time, DO NOT TRUST ANY OUTPUT FROM THE SOFTWARE WHICH YOU HAVEN'T MANUALLY VERIFIED. You should learn how to design a building like this without software. At that point, you'll have a better idea what to expect. Once you have more experience with this, then when you use the software, you'll do manual spot checks, especially for the most critical members to see if your answer agrees with the software.

 

[mronlinetutor]

Yes, all the joints are fixed for simplicity. The trusses should be pinned as I use fixed-end fixity for the structs and purlins. The building is run using steel instead of wood. I tried to use wood for the program but the program does not provide optimization using wood. No one can actually design a building without using a computer nowadays because there are so many load cases and load factors that you have to shake this building under earthquake and wind load to find the maximum stresses in the critical members in the overall structure. You have to find the worst load case amount load cases. You have to use one size for all the members for simplicity. Yes, you can use the manual calculation to spot-check the computer result but not the other way around.

disclaimer: all calculations and comments must be checked by senior engineers before they are taken to be acceptable.

 

[driftLimiter]

Almost feels like your trolling us here. This is like a textbook case of a major "no-no" in structural engineering.

Its exactly what our professors warned us about in undergrad courses.

Its not even clear what you are trying to do with the whole steel vs wood thing. Its not safe by any means.

 

[driftLimiter]

I think most here would probably be able to take you up on your challenge and design this building without a computer.

But you can neither design it by hand, nor on the computer if it isn't laid out in a constructable, and sensible fashion.
This is something the computer cannot do for you.

Structural engineers don't simply model structures into the computer and ask, "Is it Safe."

What is your lateral system for this building? What kind of foundation system?

The big pictures items need to be thought about before even entering an analysis software.

 

[SWComposites]

No one can actually design a building without using a computer nowadays OMG. GIGO. This kind of thinking that is also going on in the aerospace industry scares the **** out of me.

Putting rubbish into a computer code because "that is all it will accept" is just Wrong.

 

[mronlinetutor]

Usually, I work out my design on my computer first and then I rethink the structure. The example I provided is only a preliminary conceptual design. After that, I used Math Solver to work out the step-by-step mathematics for the structure later. Finally, I will conclude my calculations with my final design and use the computer to check it again.

disclaimer: all calculations and comments must be checked by senior engineers before they are taken to be acceptable.

 

[XR250]

I thought this dummy was blocked from the site?

 

[mronlinetutor]

This dummy is so happened to be For God.

disclaimer: all calculations and comments must be checked by senior engineers before they are taken to be acceptable.

 

[Eng16080]

No one can actually design a building without using a computer nowadays...

Anybody who cannot design a building or component of a building manually or at least have a good general idea what a reasonable design would be without using software, should:[ol 1]
[li]Not be using that software for engineering, and[/li]
[li]Should not be doing engineering, except under direct supervision[/li]
[/ol]

By the way, I'm a huge fan of software and the potential it brings. There are plenty of tasks that I cannot perform nearly as well as if I use a piece of software made for that specific task which I understand well how to use. For example, concrete anchorage design is very complicated, and I often use software for that. But if the software tells me that an anchor has a shear capacity of 10,000,000 lbs or 4 lbs and I have no clue what a reasonable answer should be, then, again, I should not be using the software until I have a better idea.

 

[mronlinetutor]

I think this building is so small that it falls within Part Nine of the Canadian National Building Code which does not require an engineer or an architect. Besides, I have studied structural engineering no lesser than any of you.

disclaimer: all calculations and comments must be checked by senior engineers before they are taken to be acceptable.

 

[Luceid]

mronlinetutor Point is - we can all see you don't know what you are doing. Replacing a wood designed building with fixed steel members is so far off

"This building is small enough that it doesn't need an engineer - but I have to use a computer because I can't design it by hand"

Yikes

 

[TORCHMAN]

As a representative of Canada, I would like to apologize to people of other nationalities for mronlinetutor's existence. We can be better.

mronlinetutor, I hope that you are trolling. If not, other members of the forum have given some helpful insight, I think best to take some time to reflect on this thread.

 

[mronlinetutor]

The existential of structural engineering is my pleasure.

disclaimer: all calculations and comments must be checked by senior engineers before they are taken to be acceptable.

 

[Luceid]

what

 

[ChorasDen]

Hard to believe this is strictly trolling, who would take the time to make a student SkyCiv account and run through a design and analysis just to troll EngTips? Seems like a lot of work for little benefit. I think these are sincere, if misguided, questions from the OP.

 

[XR250]

This dummy is so happened to be For God

Well, For God's sake (and ours), find something better to do with your time. I hear Walmart is hiring greeters.