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Arun Faegre,ALA,PE 520 SW Yamhill Street Portland Oregon 97204 (503)222-2546 FAXi222-6529 faegre�,�emthlinknet Alternative Methods Appeal for Blue Gate .Hangar 2, Aurora Airport te January 20, 2021 / A' ' ' - far Code Section for which alternative method being proposed: 707 Fire Barriers. A 3-hour fire barrier is being used to separate this hangar into two sections. The existing drawings called for a metal stud wall using GA File No. WP 2751. This alternative methods request is to request revision of this to a different system that would fit better with the existing metal building wall provided by the manufacturer,for which there already are provided horizontal metal girts between steel columns as the base structure,with diagonal lateral brace rod through the girts. Proposed Design: We would like to change the 3-hour fire barrier assembly from an 8" steel stud wall,to be UL Design U436. The center dividing wall of the Nucor building, at Bayline G, is already framed with 8" horizontal wall girts on 4'centers. Additionally this wall has 1-1/4"diameter X-bracing and two horizontal composite wide flange beams(SKP004)at the ridge. Space between these wide flanges is approximately 6". Nucor designed the Bayline G wall girts to support 18 psf of drywall and attachment materials. Using the U436 assembly does not modify or compromise original Nucor design. This assembly works for Baylines#1 to#2 and Baylines#3 to#4 from floor to underside of roofing(see Sketch#1). This assembly also works for Baylines#2 to#3 from floor to just underneath wide flanges SKPOO4 (see Sketch SK#2). We are proposing UL Des X514 to complete fire barrier at ridge. The U436 design calls for 1-5/8"25-gauge steel studs on 24"centers. We arc proposing to substitute 150F125-43 hat channels on each side of existing 8" wall gins with two#10 teks at each girt. Structural properties of the 1-1/2" 18-gauge hat channels are equivalent or superior to the 1-5/8" 25- gauge steel studs(see supporting specification sheets. Describe Reason for Alternative: This provides a solution that works with the existing metal building structure. It also ensures that the X-bracing is contained within the fire protection,which is an added improvement over the original design. Describe Why,How,etc.the Proposed Alternative is Equivalent and Meets the Intent of the Code in Terms of"Strength, Effectiveness, Fire Resistance, Durability. Health,and Safety": This alternative uses standard UL established systems for gaining the 3-hour rating while also containing the X-bracing within the fire enclosure, which is an added improvement over the original design.