Involved with a Rush job that requires installation of a 100+ feet of Longitudinal Floor rail + Brown track to secure custom seating & monuments. A typical procedure would be to duplicate the existing OEM rail installation adjacent to the proposed installation butt-line. The OEM rail installation being an extrusion (I-Channel 4" height) with integral Brown track. All is good & well except Long sections (& amounts) of extrusion (or alternate shapes) are not readily available at this time. There is the typical 33 week wait period for the Mill production upon order. As is the case - reality never holds back a client who has deep pockets & a high school level of engineering. So Forward we go!
- I suggested that duplication of the I-Beam extrusion be accomplished with a pair of C-Channel Formed angles. C-Channels back to back with a flat strap along the top. (strap used to secure the Brown track to the I-channels via center-located fastener). Rivet row along the upper web & also along the lower web as well as the strap riveted to the opposite upper flanges of the C-channels. Lots of labor - but a viable substitute - given no extrusion available. (at least in my opinion)
- Approving authority declined the substitution based on extrusion properties superior to flat sheet properties etc .. (whatever that means) Intention was to replace 7050-T76511 [Ftu 79ksi] with 7075-T6 [Ftu 78ksi] & additional thickness to compensate for lessor strength.
(secondary issues for those with deeper insight) OEM Rail notched at each xFrame - thus installation is more of a series of installed intercostals then a continuous span of beam. Clips installed at each Rail / xFrame intersection.
## Question - can anyone think of reasons why an extrusion would be superior to formed angles? I can think of efficiency in shape / possibly DTA due to fewer fastener holes. anything else come to mind??? Any reasons why a formed shape (combo shapes) with equiv Ixx to the OEM extrusion would not be a viable substitute??