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Frame Stability and determination of K Factors

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The following question was posted to the Structuralist.Net discussion forum  on Technical Discussion Forum  and posted under the subject How is frame stability basically defined and utilized in K factors? 

I believe the question is important and would ask that you consider responding to the writer on the Discussion forum so that the answers can be left for future reference by others who are considering this problem. If you do not wish to register to participate on the Structuralist.Net forum, please respond on the SEAINT list and I will transfer your response over.

Thank you for taking the time to help this engineer.

"Could someone give me a very basic explanation on how frame stability was defined in determination of K factors for use in proportioning columns?.

Was it the buckling strength of each floor or all floors at once used?.

When we use finite element software or hand calculation we perform Ga,Gb calculations between stories, how does this reflect overall stability of the complete multi-storey frame?

In Structural Stability Research Council's Guide to Stability Design of Metal Structures, Chapter 15 : Determination of K, a 2 story frame is analyzed for K first by using alignment charts and later on modified for overall frame buckling and it shows that the top story columns can have K as much as 330% of those calculated using alignment charts(i.e. between floor approach).

Sorry if this doesn't sound professional, but I have special respect for PEs because they can put an apparently complex problem into a very simple frame.

Thanks in advance"

Dennis S. Wish, PE
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