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Wind Pressure Research on Low Buildings. Peter J. Vickery Applied Research Associates, Inc. 8537 Six Forks Road, Suite 600 Raleigh, NC, 27615. Wind Tunnel Tests. Pressure Tests. Effect of Roof Slope - Gable. Effect of Roof Slope - Gable. Gable End. Gable Ridge. 4:12 Code Comparisons.
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Wind Pressure Researchon Low Buildings Peter J. Vickery Applied Research Associates, Inc. 8537 Six Forks Road, Suite 600 Raleigh, NC, 27615
Gable End Gable Ridge 4:12 Code Comparisons
Gable Ridge Gable Eave 4:12 Code Comparisons
Gable End Gable Ridge 7:12 Code Comparisons
Gable End Gable Ridge 7:12 Possible Solution
Gable Ridge Gable Eave 7:12 Code Comparisons
Gable End Gable Ridge 9:12 Code Comparisons
Gable Ridge Gable Eave 9:12 Code Comparisons
Gable End Gable Ridge 12:12 Code Comparisons
Gable Ridge Gable Eave 12:12 Code Comparisons
7:12 Hip ASCE 7-05 Gable/Hip Roofs 10°<Slope≤30° Assumes Designer uses ASCE 7-05 Gable Roof Coefficients for 30°< Slope ≤ 45°
9:12 Hip ASCE 7-05 Gable/Hip Roofs 10°<Slope≤30° Assumes Designer uses ASCE 7-05 Gable Roof Coefficients for 30°< Slope ≤ 45°
12:12 Hip ASCE 7-05 Gable/Hip Roofs 10°<Slope≤30° Assumes Designer uses ASCE 7-05 Gable Roof Coefficients for 30°< Slope ≤ 45°
Interference Effects • Exposure 4 • Exposure 3 • Exposure 5 • Exposure 6
Gable 5:12 GCp (Wind Direction 40) Sub-Urban Exposure-6 Exposure-5 Exposure-4 Exposure-3
Gable 6:12 GCp (Wind Direction 40) Sub-Urban Exposure-6 Exposure-5 Exposure-4 Exposure-3
Summary • Papers describing results are still in preparation. • Results show for gable roofs ASCE 7 coefficients for roofs are too low (not new). • Use of gable loads for hip roofs with slopes > 30° will underestimate loads. • Simple improvement could be to use the Gable/Hip 10° < θ≤ 30° for all hip roofs
Summary • Resistance to increase loads in ASCE 7 (even though data shows code loads are too high) is because of shielding • Work by Ho (1993) showed that neighboring buildings decrease wind loads by ~25% • New work shown here (based on the new 5:12 and 6:12 experiments) shows similar reductions EXCEPT near the high section gable ridge areas. • Perhaps could use this finding to force use of Exposure C for all roof C&C loads