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City of Belgrade Design Criteria 2021 IRC Basic Design Criteria IRC applies to single-family, two-family, and townhouse dwelling. Design Live Loading • IRC Table R305.1 Minimum Uniformly Distributed Live Loads • IRC Table R305.7 Allowable Deflection of Structural Members • Deck Live (snow) Load: 46 psf (Pg) Snow Load • ASCE 7 Table 7.2-4 for Montana • Ground Snow Load: 46 psf (Pg) • Roof Snow Load: 41 psf (Pm) ARM 24.301.154 Subsection R301.6 is deleted - “Snow Loads for Structural Design in Montana", Civil Engineering Department, Montana State University, 2004 revised edition IRC Section R905.1.2 Ice Barrier Required. Frost Depth • One Story: 36" (inches) minimum bottom of the footing • Two Story: 48" (inches) minimum bottom of the footing Basic Design Wind Speed Wind Speed: 115 mph IRC Figures R301.2(2), R301.2.1.1. Exposure category per IRC Section R301.2.1.4 Weathering Severe - Table R301.2(1) Seismic Design Category D0 - Section R301.2.2.1 Geotechnical (Soils) ---PAGE BREAK--- • Site-specific Geotechnical Analysis Required at permit application. • Final Observation Report submitted prior to footing inspection. 2021 IBC Basic Design Criteria Design Live Loading • IBC Table 1607.1 • Deck Live (snow) Load: 46 psf (Pg) Snow Load • ASCE 7 Table 7.2-4 for Montana • Ground Snow Load: 46 psf (Pg) • Roof Snow Load: 41 psf (Pm) ARM 24.301.146 (23) Subsection 1608.2 is deleted - "Snow Loads for Structural Design in Montana", Civil Engineering Department, Montana State University, 2004 Revised Edition. IBC Section 1507.1.2 Ice Barrier Required. Frost Depth • One Story: 36" (inches) minimum bottom of the footing • Two Story: 48" (inches) minimum bottom of the footing Basic Design Wind Speed (3-Second gust) • Wind Speed: 115 mph Using IBC Figures 1609.3(1), 1609.3(2), 1609.3(3), and 1609.3(4). Exposure category per IBC Section 1609.4 Seismic Design Category: D Use this basic procedure to determine the Seismic Design Category: 1. Determine the mapped maximum considered earthquake spectral response acceleration at short periods(Ss) and at 1-second period (S1), for the site location from IBC Figures 1613.2.1(1) through 1613.2.1(8) 2. Determine the (soil) site class in accordance with ASCE 7 3. Determine the site coefficients Fa and Fv from IBC Tables 1613.2.3(1) and 1613.2.3(2), respectively ---PAGE BREAK--- 4. Determine the 5-percent damped design spectral response acceleration at short periods (SDS) as follows: SDS = (2/3)(SMS) SD1 = (2/3)(SM1) 5. Determine the seismic design category as prescribed by Tables 1613.2.5(1) and 1613.2.5(2). The highest of the seismic design categories from the two tables is the category assigned. Geotechnical (Soils) • Site-specific Geotechnical Analysis Required at permit application. • Final Observation Report submitted prior to footing inspection.