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How to apply loads to Truss...

How to apply loads to Truss...

How to apply loads to Truss...

(OP)
Some of you may have read my previous posts pertaining to my Truss analysis questions....

I am wondering the correct way to apply loads to a truss I am analyzing? I determined the Wind loads, snow loads, and dead loads, but Ia m a bit unsure as to how to apply them? Would I go with the highest of the factored load conditions listed on ASCE 07-xx, or just analyze with actual loads sine I am not designing this for new build, but just analysis?


Thanks again all. Previous help has been much appreciated.

RE: How to apply loads to Truss...

(OP)

Another question...

Since the loads ona truss are assumed to eb at the joints, I guess I must resolve the uniform DL and LL into point loads? Would you distribute the laods eavenly betweent the loints?

I am analyzing a Fink truss for the first time and I'm a little stumped on the particulars right now.

Thanks again

RE: How to apply loads to Truss...

Adam,

I would suggest you had a thorough look at an engineering book, where trusses are explained with detail, usually in first chapters.

Analysis and Design of arbitrary cross sections
Reinforcement design to all major codes
Moment Curvature analysis

http://www.engissol.com/cross-section-analysis-des...

RE: How to apply loads to Truss...

The problem with not applying the loads to the members as opposed to the joints is that moments in the members at the joints are ignored when the members are continuous through the joints.

This was a part of the problem with the analysis of Bow String Trusses in the 50's, contributing to their shoddy reputation.

Consequently, I almost alway load the truss as the loads actually occur, and that is not at the joints.

Mike McCann
MMC Engineering

RE: How to apply loads to Truss...

Resolving the distributed loads into point loads will give you a pretty good handle on the axial loads of the truss members however to fully understand and design the truss you need to know the bending moments. The best way to determine those is using Matrix Analysis. I strongly recommend Structural Analysis by R.C Hibbeler (chapter 16) as a good primer. ANSI TP1-2007 and the NDS will give you all of the details on determining the combined loading for the top and bottom chords. You can also get most of this in a nutshell by looking at http://design.medeek.com/calculator/calculator.pl (fink truss).

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