SPECIFICATION FOR THE DESIGN OF - Transcon Steel

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18 Commentary on the Prescriptive Method for One and Two Family Dwellings - 2004 • Buildings are considered regular (rectangular shape) • First and second story walls are assumed vertically stacked (no offset) Weights used in calculating the entries of the tables in the high seismic areas are as follows: • Roof/ceiling dead load = 25 psf (1.2 kN/m 2 ) for heavy weight roofs = 15 psf (0.72 kN/m 2 ) for normal weight roofs = 12 psf (0.57 kN/m 2 ) for light weight roof systems • Wall dead load = 14 psf (0.67 kN/m 2 ) for heavy walls = 7 psf (0.34 kN/m 2 ) for light walls • Floor/ceiling dead load = 10 psf (0.48 kN/m 2 ) • Interior wall dead load = 5 psf (0.24 kN/m 2 ) (based on 10 foot (3.04 m) wall) • Ground snow load = 30 psf (1.44 kN/m 2 ) for normal or light weight roofs = 70 psf (3.35 kN/m 2 ) for heavy weight roof systems • Roof weight includes a 2-foot (610 mm) overhang The dead loads that were used in determining the seismic mass are given below: Wall Element Weight (psf) Light Weight Walls Heavy Weight Walls Wallboard 1.8 1.8 <strong>Steel</strong> Framing 0.6 0.6 ½” Plywood Sheathing 1.6 1.6 Insulation 1.0 1.0 7/8” Stucco 0 9.0 Exterior Siding 1.5 0 Total 6.5 14.0 For SI: 1 psf = 0.0479 kN/m 2 . Roof Element Weight (psf) Flat Roofs Sloped Roofs (6:12) Sheathing 1.6 1.63 Roof Framing or Trusses 2.5 2.5 Insulation 1.0 1.0 Miscellaneous 0.6 0.84 Ceiling Covering 1.8 1.8 Subtotal 7.5 7.8 Total with Roof 3.7 psf Covering 11.5 12 Total with Roof 6.4 psf Covering 14.2 15 Total with Roof 15.3 psf Covering 23.5 25 For SI: I psf = 0.0479 kN/m 2 .
Commentary on the Prescriptive Method for One and Two Family Dwellings - 2004 19 Roof Category Roof/Ceiling Weight (psf) Light-Weight Roof 12 Normal-Weight Roof 15 Heavy-Weight Roof 25 For SI: 1 psf = 0.0479 kN/m 2 . Design assumptions that are used in developing the shear wall and other tables in the high seismic areas are as follow: • Nominal shear values are taken from Table 2211.1(3) of the International Building Code (IBC) (ICC, 2000a) • Seismic Design Category (SDC) assignments in accordance with Table R301.2.2.1.1 of the International Residential Code (ICC, 2000b) • Seismic base shears were calculated in accordance with the IBC (ICC, 2000a) using an R = 5.5 and Ω 0 = 2.5. Upper end S DS values are used for each SDC • Diaphragms are considered to be flexible rather than rigid. No requirement for inclusion of accidental torsion and reduction of Ω 0 from 3 to 2.5 in accordance with the IBC (ICC, 2000a) was used • φ factor was used in combination with the Ω 0 over strength factor to determine screw requirements for chord splices • F u = 45 ksi (310 MPa) and F y = 33 ksi (230 MPa) were used in lieu of the IRC (ICC, 2000b) allowed 1.08 tensile/yield ratio in determining screw capacities. Shear wall test values are based on the 33 ksi/45 ksi (230/310 MPa) steels • Chord splice screw requirements are based on the lesser of Ω 0 times T seismic or T n , divided by φ V n . Both the 3-1/2 inch (88.9 mm) and the 5-1/2 inch (140 mm) members were considered, as well as both the 33 mil (0.84 mm) and the 43 mil (1.09 mm) thickness • Where the ground snow load is 70 psf (3.35 kN/m 2 ), the heavy roof system criteria applies Example: Load due to 70 psf ground snow load for normal weight roofs = 15 psf + 0.2x0.7x70 psf = 24.8 psf (1.19 kN/ m 2 ) (equals the heavy weight roof systems) E11.2 Braced Wall Lines Two types of braced wall lines are presented in this section: Type I and Type II Braced Walls. Type I braced walls are traditional shear walls that have a hold down anchor at each end and have no openings between anchors. Type II braced walls, also known as perforated shear walls, are shear walls that have openings between anchors and there is no design for shear transfer around the openings. E11.3 Type I (Solid Sheathed) Braced Wall Panels This section describes the traditional method of sheathing a steel-framed wall where continuous panels have hold down anchors at each end. The aspect ratio used in the development of these provisions for this wall type is 2:1.
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SPECIFICATION FOR THE DESIGN OF - Transcon Steel

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