High ductile requirements for T section 1

[compe_ad]

Why most of the T-section does not satisfy the width-to-thickness requirement of high ductile members (Table D1.1 of seismic provision)? I am trying to use T-section for the top and bottom chords of special steel truss moment frame and looks like most of the section does not satisfy. What type of section will be appropriate for the top and bottom chords, any suggestions?

 

[KootK]

Why most of the T-section does not satisfy the width-to-thickness requirement of high ductile members (Table D1.1 of seismic provision)?

Tee members are traditionally wide flange beams cut into Tee shapes. So it's unsurprising, to me at least, that a web thickness meant to be stocky when supported laterally top and bottom (WF) gets more slender when it becomes a cantilever (tee). Basically, because tees are derivative shapes, no one bothered to make their webs stocky for that scenario.

What type of section will be appropriate for the top and bottom chords, any suggestions?

- Wide flange sections.

- HSS sections.

... probably other things that I've not thought of.

 

[haynewp]

I designed a STMF about 3 years ago and it was a real PITA to make it work. I used heavy angle sections for the chords. See the AISC Seismic Manual for an example if you don't have it already, that's what I followed for the entire design. The example is about 40 pages long.

 

[compe_ad]

I don't think there is an example for STMF in AISC seismic manual. I can find for other systems but not for STMF.

 

[haynewp]

It's in there, starting on page 4-128 of the 3rd edition.

 

[compe_ad]

Thanks! I was looking at second edition.