Buckling Analysis of Spaceframe Using Beamend Force from Stress Analysis

Where is your FEA and CFD analysis? The system has to be evaluated and modeled as a complete structure, location specific, under design guidelines for that area...

http://www.osti.gov/scitech/servlets/purl/1069235

I agree.

I don't agree. Looks like the designer is going old school the way we did it before FEA and CFD.

You identify the structure loads, get worst case and then free-body through the structure and verify each element. It worked in the good old days with the slide rules and ledger pads.

With a safety factor of 5 you should be good, but only as good as the job you did identifying the worst case loadings. It is likely that you will have several cases of loading, such as storm wind and precipitation, snow loading (not really in India), bird perching, protesters climbing over the structure, etc. As with FEA and CFD, your results are only as good as your identified inputs.

Thanks a lot for all your valuable insights. A whole lot of complications are being raised when trying to perform buckling analysis taking the whole structure, especially the processing time is taking ages due to complexity of various members, joints etc.,

So, we decided to go first for critical stress analysis of whole system with load combinations as (A+B+C+D)

A. Wind Loads @

1. Criteria : During storms, system at parking position (horizaontally), wind loads @ 200 kmph considering the vertical projected area when system is at 0°

2. Criterias: During operating conditions, wind speeds @ 60kmph, System @ various angles like 1°, 10°,20°,30°,40°,50°,60° & 70°. Taking the respective vertical projected areas for each position.

B. Mirror/Live Loads

C. Receiver Loads

D. Dead Loads

In each case (system @ 1°, 10°,20°,30°,40°,50°,60° & 70°), load combination (A+B+C+D) had been taken and respective maximum beam end forces for each case is noted. Finally, a master list consisting of max. forces of every beam element considering all the cases is listed. Taking these forces as input for buckling analysis, using Euler formula, each beam member is configured so that it will meet the design criteria of factor of safety of 5 against buckling load failure.

This method is rather a conservative approach. But we feel this method is way much better than all in one analysis setup as the input conditions in FEA/CFD are huge, even a small parameter is wrongly fed, results will be varied.

Thanks again for giving your valuable inputs. Learning a lot from people like you.

Looking forward for varied opinions.

I would think a safety factor 5 over Euler is adequate, provided the compressive loads in each member are known with reasonable accuracy (as per your #4). I assume the n in the formula is the factor for end conditions, not the safety factor.