RE: Required Strength for EBF Column

Seth Guthrie — Wed, 28 Aug 2019 21:46:29 GMT

Without actually going thru old models I would guess that BRBFs are becoming popular. Special Moment frames (with or without Side Plates) and Special Concentrically Braced Frames too.

RE: Required Strength for EBF Column

John Gervais — Wed, 28 Aug 2019 21:09:07 GMT

Personally, this would be my first EBF design, so I am digging extra deep into the analysis and design process that RAM uses to engineer them. In doing so, I have been using an EBF design spreadsheet created and verified by our senior seismic engineer and back checking the results that RAM has been producing. In general, RAM has been producing more efficient results, aside from this column design issue.

From an engineering standpoint, it seems like it would be rather simple to adjust the design check in RAM to consider the actual adjusted shear strength values of the link beams in the stories above instead of relying on the application of an amplification factor under assumed conditions. However, from a computer software standpoint, this may well be a much harder process to execute.

Over the last few years, our office has been doing a number of steel-framed buildings on the West Coast in high-seismic areas. For these projects, a lot of them had building characteristics that best suited the use of EBFs versus other seismic systems. Until now, we have been using a combination ETABS and spreadsheets to design the lateral system for these structures, but after reviewing the seismic analysis and design capabilities of RAM Frame, I wanted to try it out.

In general, do you see many models for projects with lateral systems for high-seismic areas? What sort of systems have they been using? Are their structures just naturally better suited for systems other than EBF, or are they using other systems in lieu of EBFs?

RE: Required Strength for EBF Column

Seth Guthrie — Wed, 28 Aug 2019 20:22:25 GMT

What you are saying is correct and our approach is an oversimplification of the design. An enhancement is needed, but it's rather complex to execute. Do you do a lot of EBF designs? Just based on the models I see from users, they seem to be less common now.