non uniform load over continuous spans 1

[cmbyrd77]

Just wanted to pick the brains of my fellow engineers out there. In your experience how have you gone about calculating shear/moment/deflection on a continuously supported member with a non-uniform (triangular) load. Obviously there is the easy answer of you can take the average and turn it into a uniform load and then use the moment and shear coefficeints from AISC. Or, there is the option of plugging and chugging in a computer (not a fan). Just curious of others' approach to this. Thanks to everyone who contributes on here.

 

[JAE]

With the ease of use and affordability of software, hand-solving a problem like that is not to my liking.

 

[Lion06]

I'm with JAE. With all of the engineering and detailing that needs to be done on a project, this is not where you want to spend your time.

 

[BAretired]

If it doesn't make a huge economic impact on the job, why not simply adopt some conservative loading assumptions and press on? If you are using AISC coefficients, you aren't expecting a very precise solution anyway.

BA

 

[Archie264]

Agree with all of the above. Having said that, it wouldn't hurt to have the Hardy Cross/moment distribution method in your bag of tricks. An experienced old-timer can use that to solve the problem you just mentioned faster than you can input the parameters into your computer. Literally.

I try to solve a couple of these by hand periodically. I aspire to be as good as the slide-rule era folks someday (to include the participant on this board that uses that moniker). And don't tell anyone but I still write with cursive.

But remember, the SR-71 was designed with a slide rule and the Osprey and F-35 debacles were designed with computers. Something to think about, to hopefully keep us humble...

 

[rb1957]

"Obviously there is the easy answer of you can take the average and turn it into a uniform load" ... i wouldn't as the triangular dist'n will peak and cause internal moments higher than the average load as UDL.

for my money, BA's simple solution would mean using the peak as a UDL ... clearly conservative.

Quando Omni Flunkus Moritati

 

[JAE]

Archie264 - I'll race you with my RISA2D!

 

[msquared48]

Well, I use BeamPro, but when the stuff hits the fan, I still have my slide rules, and know how to use them - at least today I do.

Mike McCann
MMC Engineering

 

[Archie264]

JAE, you'll beat me by a mile, no question about it! But I'm seen someone in action that might have been able to give you a run for your money. He's no longer with us though, sadly.

 

[Bagman2524]

On a similar vein Socrates Ioannides of Structural Affiliates International in Nashville as a publication on Rules of Thumb for Steel Design that allows you to estimate member sizes very quickly.

 

[rb1957]

"the SR-71 was designed with a slide rule and the Osprey and F-35 debacles were designed with computers" ... don't blame the tools (no pun intended) ... the SR71 was designed by the guys who taught the guys who taught the guys who did VF22 and F35 ... so do you want the teachers or the students ?

VF22 shows that enough time and money can overcome all obstacles ...

Quando Omni Flunkus Moritati

 

[AELLC]

If you have Excel, this does it easily

 

[Archie264]

rb1957, I knew better than to bring that up since it's way out of my element. It's all I can do to try to learn about my own discipline.

 

[TDIengineer]

Let me guess... you're checking snow drift loading?

Lots of triangles in that!!!