The following definitions apply to the provisions of Chapters 26 through 31: APPROVED: Acceptable to the authority having jurisdiction. BASIC WIND SPEED, V: Three-second gust speed at 33 ft (10 m) above the ground in Exposure C (see Section 26.7.3) as determined in accordance with Section 26.5.1. BUILDING, ENCLOSED: A building that does not comply with the requirements for open or partially enclosed buildings. BUILDING ENVELOPE: Cladding, roofing, exterior walls, glazing, door assemblies, window assemblies, skylight assemblies, and other components enclosing the building. BUILDING AND OTHER STRUCTURE, FLEXIBLE: Slender buildings and other structures that have a fundamental natural frequency less than 1 Hz. BUILDING, LOW-RISE: Enclosed or partially enclosed buildings that comply with the following conditions:.
Mean roof height h less than or equal to 60 ft (18 m) and. Mean roof height h does not exceed least horizontal dimension. BUILDING, OPEN: A building having each wall at least 80% open. In areas outside hurricane-prone regions, regional climatic data shall only be used in lieu of the basic wind speeds given in Fig.
26.5-1 when (1) approved extreme-value statistical-analysis procedures have been employed in reducing the data; and (2) the length of record, sampling error, averaging time, anemometer height, data quality, and terrain exposure of the anemometer have been taken into account. Reduction in basic wind speed below that of Fig. 26.5-1 shall be permitted. In hurricane-prone regions, wind speeds derived from simulation techniques shall only be used in lieu of the basic wind speeds given in Fig.
26.5-1 when approved simulation and extreme value statistical analysis procedures are used. The use of regional wind speed data obtained from anemometers is not permitted to define the hurricane wind-speed risk along the Gulf and Atlantic coasts, the Caribbean, or Hawaii. In areas outside hurricane-prone regions, when the basic wind speed is estimated from regional climatic data, the basic wind speed shall not be less than the wind speed associated with the specified mean recurrence interval, and the estimate shall be adjusted for equivalence to a 3-sec gust wind speed at 33 ft (10 m) above ground in Exposure C. The data analysis shall be performed in accordance with this chapter. FIGURE 26.5-1A Basic Wind Speeds for Risk Category II Buildings and Other Structures Notes:. Values are design 3-second gust wind speeds in miles per hour (m/s) at 33 ft (10m) above ground for Exposure C category.
Linear interpolation between contours is permitted. Islands and coastal areas outside the last contour shall use the last wind speed contour of the coastal area. Mountainous terrain, gorges, ocean promontories, and special wind regions shall be examined for unusual wind conditions. Wind speeds correspond to approximately a 7% probability of exceedance in 50 years (annual exceedance probability = 0.00143, MRI = 700 years). FIGURE 26.5-1A ( Continued) FIGURE 26.5-1B Basic Wind Speeds for Risk Category III and IV Buildings and Other Structures Notes:. Values are design 3-second gust wind speeds in miles per hour (m/s) at 33 ft (10m) above ground for Exposure C category.
Linear interpolation between contours is permitted. Islands and coastal areas outside the last contour shall use the last wind speed contour of the coastal area. Mountainous terrain, gorges, ocean promontories, and special wind regions shall be examined for unusual wind conditions. Wind speeds correspond to approximately a 3% probability of exceedance in 50 years (annual exceedance probability = 0.000588, MRI = 1700 years). FIGURE 26.5-1B ( Continued) FIGURE 26.5-1C Basic Wind Speeds for Risk Category I Buildings and Other Structures Notes:. Values are design 3-second gust wind speeds in miles per hour (m/s) at 33 ft (10m) above ground for Exposure C category. Linear interpolation between contours is permitted.
Islands and coastal areas outside the last contour shall use the last wind speed contour of the coastal area. Mountainous terrain, gorges, ocean promontories, and special wind regions shall be examined for unusual wind conditions.
Wind speeds correspond to approximately a 15% probability of exceedance in 50 years (annual exceedance probability = 0.00333, MRI = 300 years). FIGURE 26.5-1C ( Continued) Wind Directionality Factor, K d Table 26.6-1 Structure Type Directionality Factor K d. Buildings Main Wind Force Resisting System Components and Cladding 0.85 0.85 Arched Roofs 0.85 Chimneys, Tanks, and Similar Structures Square Hexagonal Round 0.90 0.95 0.95 Solid Freestanding Walls and Solid Freestanding and Attached Signs 0.85 Open Signs and Lattice Framework 0.85 Trussed Towers Triangular, square, rectangular All other cross sections 0.85 0.95.Directionality Factor K d has been calibrated with combinations of loads specified in Chapter 2.
This factor shall only be applied when used in conjunction with load combinations specified in Sections 2.3 and 2.4. Exposure B: For buildings with a mean roof height of less than or equal to 30 ft (9.1 m), Exposure B shall apply where the ground surface roughness, as defined by Surface Roughness B, prevails in the upwind direction for a distance greater than 1,500 ft (457 m). For buildings with a mean roof height greater than 30 ft (9.1 m), Exposure B shall apply where Surface Roughness B prevails in the upwind direction for a distance greater than 2,600 ft (792 m) or 20 times the height of the building, whichever is greater. Exposure C: Exposure C shall apply for all cases where Exposures B or D do not apply. Exposure D: Exposure D shall apply where the ground surface roughness, as defined by Surface Roughness D, prevails in the upwind direction for a distance greater than 5,000 ft (1,524 m) or 20 times the building height, whichever is greater. Exposure D shall also apply where the ground surface roughness immediately upwind of the site is B or C, and the site is within a distance of 600 ft (183 m) or 20 times the building height, whichever is greater, from an Exposure D condition as defined in the previous sentence.
For a site located in the transition zone between exposure categories, the category resulting in the largest wind forces shall be used. EXCEPTION: An intermediate exposure between the preceding categories is permitted in a transition zone provided that it is determined by a rational analysis method defined in the recognized literature.
Wind speed-up effects at isolated hills, ridges, and escarpments constituting abrupt changes in the general topography, located in any exposure category, shall be included in the determination of the wind loads when buildings and other site conditions and locations of structures meet all of the following conditions:. The hill, ridge, or escarpment is isolated and unobstructed upwind by other similar topographic features of comparable height for 100 times the height of the topographic feature (100 H) or 2 mi (3.22 km), whichever is less.
This distance shall be measured horizontally from the point at which the height H of the hill, ridge, or escarpment is determined. The hill, ridge, or escarpment protrudes above the height of upwind terrain features within a 2-mi (3.22-km) radius in any quadrant by a factor of two or more. The structure is located as shown in Fig. 26.8-1 in the upper one-half of a hill or ridge or near the crest of an escarpment. H/L h ≥ 0.2. H is greater than or equal to 15 ft (4.5 m) for Exposure C and D and 60 ft (18 m) for Exposure B.
Topographic Factor, K zt Figure 26.8-1 Topographic Multipliers for Exposure C H/L h K 1 Multiplier x/L h K 2 Multiplier z/L h K 3 Multiplier 2-D Ridge 2-D Escarp. Hill 2-D Escarp. All Other Cases 2-D Ridge 2-D Escarp. Hill 0.20 0.29 0.17 0.21 0.00 1.00 1.00 0.00 1.00 1.00 1.00 0.25 0.36 0.21 0.26 0.50 0.88 0.67 0.10 0.74 0.78 0.67 0.30 0.43 0.26 0.32 1.00 0.75 0.33 0.20 0.55 0.61 0.45 0.35 0.51 0.30 0.37 1.50 0.63 0.00 0.30 0.41 0.47 0.30 0.40 0.58 0.34 0.42 2.00 0.50 0.00 0.40 0.30 0.37 0.20 0.45 0.65 0.38 0.47 2.50 0.38 0.00 0.50 0.22 0.29 0.14 0.50 0.72 0.43 0.53 3.00 0.25 0.00 0.60 0.17 0.22 0.09 3.50 0.13 0.00 0.70 0.12 0.17 0.06 4.00 0.00 0.00 0.80 0.09 0.14 0.04 0.90 0.07 0.11 0.03 1.00 0.05 0.08 0.02 1.50 0.01 0.02 0.00 2.00 0.00 0.00 0.00. Notes:. For values of H/L h, x/L h and z/L h other than those shown, linear interpolation is permitted.
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For H/L h 0.5, assume H/L h = 0.5 for evaluating K 1 and substitute 2H for L h for evaluating K 2 and K 3. Multipliers are based on the assumption that wind approaches the hill or escarpment along the direction of maximum slope. Notation: H: Height of hill or escarpment relative to the upwind terrain, in feet (meters).
L h: Distance upwind of crest to where the difference in ground elevation is half the height of hill or escarpment, in feet (meters). K 1: Factor to account for shape of topographic feature and maximum speed-up effect. K 2: Factor to account for reduction in speed-up with distance upwind or downwind of crest.
K 3: Factor to account for reduction in speed-up with height above local terrain. X: Distance (upwind or downwind) from the crest to the building site, in feet (meters). Z: Height above ground surface at building site, in feet (meters). Μ: Horizontal attenuation factor. Γ: Height attenuation factor. Topographic Factor, K zt Figure 26.8-1 (cont'd).
As an alternative to performing an analysis to determine n 1, the approximate building natural frequency, n a, shall be permitted to be calculated in accordance with Section 26.9.3 for structural steel, concrete, or masonry buildings meeting the following requirements:. The building height is less than or equal to 300 ft (91 m), and. The building height is less than 4 times its effective length, L eff The effective length, L eff, in the direction under consideration shall be determined from the following equation.
Glazed openings shall be protected in accordance with. In the following locations:. Within 1 mi of the coastal mean high water line where the basic wind speed is equal to or greater than 130 mi/h (58 m/s), or.
In areas where the basic wind speed is equal to or greater than 140 mi/h (63 m/s). For Risk Category II buildings and other structures and Risk Category III buildings and other structures, except health care facilities, the wind-borne debris region shall be based on Fig. For Risk Category III health care facilities and Risk Category IV buildings and other structures, the wind-borne debris region shall be based on Fig. Risk categories shall be determined in accordance with. Glazing in buildings requiring protection shall be protected with an impact-protective system or shall be impact-resistant glazing. Impact-protective systems and impact-resistant glazing shall be subjected to missile test and cyclic pressure differential tests in accordance with ASTM E1996 as applicable. Testing to demonstrate compliance with ASTM E1996 shall be in accordance with ASTM E1886.
Impact-resistant glazing and impact-protective systems shall comply with the pass/fail criteria of Section 7 of ASTM E1996 based on the missile required by Table 3 or Table 4 of ASTM E1996. EXCEPTION: Other testing methods and/or performance criteria are permitted to be used when approved.
Glazing and impact-protective systems in buildings and other structures classified as Risk Category IV in accordance with shall comply with the 'enhanced protection' requirements of Table 3 of ASTM E1996. Glazing and impact-protective systems in all other structures shall comply with the 'basic protection' requirements of Table 3 of ASTM E1996. User Note: The wind zones that are specified in ASTM El996 for use in determining the applicable missile size for the impact test have to be adjusted for use with the wind speed maps of ASCE 7-10 and the corresponding wind borne debris regions, see Section C26.10.3.2.
This chapter applies to the determination of wind pressures on components and cladding (C&C) on buildings. Part 1 is applicable to an enclosed or partially enclosed Low-rise building (see definition in Section 26.2) or Building with h ≤ 60 ft ( m). The building has a flat roof, gable roof, multispan gable roof, hip roof, monoslope roof, stepped roof, or sawtooth roof, and the wind pressures are calculated from a wind pressure equation. Part 2 is a simplified approach and is applicable to an enclosed Low-rise building (see definition in Section 26.2) or Building with h ≤ 60 ft ( m). The building has a flat roof, gable roof, or hip roof, and the wind pressures are determined directly from a table. Part 3 is applicable to an enclosed or partially enclosed building with h 60 ft ( m).
The building has a flat roof, pitched roof, gable roof, hip roof, mansard roof, arched roof, or domed roof, and the wind pressures are calculated from a wind pressure equation. Part 4 is a simplified approach and is applicable to an enclosed building with h ≤ 160 ft (48.8 m). The building has a flat roof, gable roof, hip roof, monoslope roof, or mansard roof, and the wind pressures are determined directly from a table.
Part 5 is applicable to an open building of all heights having a pitched free roof, monoslope free roof, or trough free roof. Part 6 is applicable to building appurtenances such as roof overhangs and parapets and rooftop equipment. Based on the exposure category determined in Section 26.7.3, a velocity pressure exposure coefficient K z or K h, as applicable, shall be determined from Table 30.3-1.
For a site located in a transition zone between exposure categories, that is, near to a change in ground surface roughness, intermediate values of K z or K h, between those shown in Table 30.3-1 are permitted, provided that they are determined by a rational analysis method defined in the recognized literature. Velocity Pressure Exposure Coefficients, K h and K z Table 30.3-1 Notes:. The velocity pressure exposure coefficient Kz may be determined from the following formula: For 15 ft. ≤ z ≤ z g For z. The provisions of Section 30.4 are applicable to an enclosed and partially enclosed. Low-rise building (see definition in Section 26.2) or.
Building with h ≤ 60 ft (18.3 m). The building has a flat roof, gable roof, multispan gable roof, hip roof, monoslope roof, stepped roof, or sawtooth roof. The steps required for the determination of wind loads on components and cladding for these building types are shown in Table 30.4-1.
Table 30.4-1 Steps to Determine C&C Wind Loads for Enclosed and Partially Enclosed Low-Rise Buildings Step 1: Determine risk category, see Table 1.5-1 Step 2: Determine the basic wind speed, V, for applicable risk category, see Fig. 26.5-1A, B, or C Step 3: Determine wind load parameters. Walls, see Fig. 30.4-1. Flat roofs, gable roofs, hip roofs, see Fig.
30.4-2. Stepped roofs, see Fig. 30.4-3. Multispan gable roofs, see Fig. 30.4-4. Monoslope roofs, see Fig.
30.4-5. Sawtooth roofs, see Fig. 30.4-6. Domed roofs, see Fig. 30.4-7. Arched roofs, see Fig.
27.4-3 note 4 Step 7: Calculate wind pressure, p, Eq. 30.4-1 Components and Cladding h ≤ 60 ft. Figure 30.4-1 External Pressure Coefficients, GC p Walls Enclosed, Partially Enclosed Buildings Notes:. Vertical scale denotes GC p to be used with q h. Horizontal scale denotes effective wind area, in square feet (square meters).
Plus and minus signs signify pressures acting toward and away from the surfaces, respectively. Each component shall be designed for maximum positive and negative pressures. Values of GC p for walls shall be reduced by 10% when θ ≤ 10°. Notation: a: 10 percent of least horizontal dimension or 0.4h, whichever is smaller, but not less than either 4% of least horizontal dimension or 3 ft (0.9 m). H: Mean roof height, in feet (meters), except that eave height shall be used for θ ≤ 10°. Θ: Angle of plane of roof from horizontal, in degrees.
Components and Cladding h ≤ 60 ft. Figure 30.4-2A External Pressure Coefficients, GC p Gable Roofs θ ≤ 7° Enclosed, Partially Enclosed Buildings Notes:. Vertical scale denotes GC p to be used with q h. Horizontal scale denotes effective wind area, in square feet (square meters). Plus and minus signs signify pressures acting toward and away from the surfaces, respectively. Each component shall be designed for maximum positive and negative pressures.
If a parapet equal to or higher than 3 ft (0.9m) is provided around the perimeter of the roof with θ ≤ 7°, the negative values of GC p in Zone 3 shall be equal to those for Zone 2 and positive values of GC p in Zones 2 and 3 shall be set equal to those for wall Zones 4 and 5 respectively in Figure 30.4-1. Values of GC p for roof overhangs include pressure contributions from both upper and lower surfaces. Notation: a: 10 percent of least horizontal dimension or 0.4h, whichever is smaller, but not less than either 4% of least horizontal dimension or 3 ft (0.9 m).
H: Eave height shall be used for θ ≤ 10°. Θ: Angle of plane of roof from horizontal, in degrees. Components and Cladding h ≤ 60 ft. Figure 30.4-2B External Pressure Coefficients, GC p Gable/Hip Roofs 7°. P = q h( GC p) - ( GC pi) (lb/ft 2) (N/m 2) (30.4-1) where q h = velocity pressure evaluated at mean roof height h as defined in (GC p) = external pressure coefficients given in: - Figure 30.4-1 (walls) - Figures.
30.4-2A to 30.4-2C (flat roofs, gable roofs,and hip roofs) - Figure 30.4-3 (stepped roofs) - Figure 30.4-4 (multispan gable roofs) - Figures 30.4-5A and 30.4-5B (monoslope roofs) - Figure 30.4-6 (sawtooth roofs) - Figure 30.4-7 (domed roofs) - Figure 27.4-3, note 4 (arched roofs) (GC pi) = internal pressure coefficient given in Table 26.11-1 User Note: Use Part 1 of to determine wind pressures on C&C of enclosed and partially enclosed low-rise buildings having roof shapes as specified in the applicable figures. The provisions in Part 1 are based on the envelope procedure with wind pressures calculated using the specified equation as applicable to each building surface.
For buildings for which these provisions are applicable, this method generally yields the lowest wind pressures of all analytical methods contained in this standard. The provisions of Section 30.5 are applicable to an enclosed. Low-rise building (see definition in Section 26.2) or. Building with h ≤ 60 ft (18.3 m). The building has a flat roof, gable roof, or hip roof.
The steps required for the determination of wind loads on components and cladding for these building types are shown in Table 30.5-1. Table 30.5-1 Steps to Determine C&C Wind Loads for Enclosed Low-Rise Buildings (Simplified Method) Step 1: Determine risk category, see Table 1.5-1 Step 2: Determine the basic wind speed, V, for applicable risk category see Figure 26.5-1A, B, or C Step 3: Determine wind load parameters:. Exposure category B, C, or D, see Section 26.7. Topographic factor, K zt, see Section 26.8 and Figure 26.8-1 Step 4: Enter figure to determine wind pressures at h = 30 ft., p net30, see Fig. 30.5-1 Step 5: Enter figure to determine adjustment for building height and exposure, λ, see Fig.
30.5-1 Step 6: Determine adjusted wind pressures, p net, see Eq. Components and Cladding - Method 1 h ≤ 60 ft. Figure 30.5-1 Design Wind Pressures Walls & Roofs Enclosed Buildings Notes:. Pressures shown are applied normal to the surface, for exposure B, at h=30 ft (9.1 m).
Adjust to other conditions using Equation 30.5-1. Plus and minus signs signify pressures acting toward and away from the surfaces, respectively.
For hip roofs with θ ≤ 25°, Zone 3 shall be treated as Zone 2. For effective wind areas between those given, value may be interpolated, otherwise use the value associated with the lower effective wind area.
Notation: a: 10 percent of least horizontal dimension or 0.4h, whichever is smaller, but not less than either 4% of least horizontal dimension or 3 ft (0.9 m). H: Mean roof height, in feet (meters), except that eave height shall be used for roof angles. For the design of components and cladding the building shall comply with all the following conditions:. The mean roof height h must be less than or equal to 60 ft ( m) h ≤ 60 ft ( m). The building is enclosed as defined in and conforms to the wind-borne debris provisions of Section. The building is a regular-shaped building or structure as defined in. The building does not have response characteristics making it subject to across-wind loading, vortex shedding, or instability due to galloping or flutter; and it does not have a site location for which channeling effects or buffeting in the wake of upwind obstructions warrant special consideration.
The building has either a flat roof, a gable roof with θ ≤ 45°, or a hip roof with θ ≤ 27°. P net = λ K ztp net30 (30.5-1) where λ = adjustment factor for building height and exposure from Fig.
30.5-1 K zt = topographic factor as defined in evaluated at 0.33 mean roof height, 0.33h p net30 = net design wind pressure for Exposure B, at h = 30 ft (9.1 m), from Fig. 30.5-1 User Note: Part 2 of is a simplified method to determine wind pressures on C&C of enclosed low-rise buildings having flat, gable, or hip roof shapes. The provisions of Part 2 are based on the envelope procedure of Part 1 with wind pressures determined from a table and adjusted as appropriate. The provisions of Section 30.6 are applicable to an enclosed or partially enclosed building with a mean roof height h 60 ft. (18.3 m) with a flat roof, pitched roof, gable roof, hip roof, mansard roof, arched roof, or domed roof. The steps required for the determination of wind loads on components and cladding for these building types are shown in Table 30.6-1.
Table 30.6-1 Steps to Determine C&C Wind Loads for Enclosed or Partially Enclosed Building with h 60 ft Step 1: Determine risk category, see Table 1.5-1 Step 2: Determine the basic wind speed, V, for applicable risk category, see Figure 26.5-1A, B, or C Step 3: Determine wind load parameters:. Wind directionality factor, K d, see Section 26.6 and Table 26.6-1. Exposure category B, C, or D, see Section 26.7. Topographic factor, K zt, see Section 26.8 and Fig. 26.8-1. Enclosure classification, see Section 26.10. Internal pressure coefficient, (GC pi), see Section 26.11 and Table 26.11-1 Step 4: Determine velocity pressure exposure coefficient, K z or K h, see Table 30.3-1 Step 5: Determine velocity pressure, q h, Eq.
30.3-1 Step 6: Determine external pressure coefficient, (GC p). Walls and flat roofs (θ 60 ft Figure 30.6-1 External Pressure Coefficients, GC p Walls & Roofs Enclosed, Partially Enclosed Buildings Notes:. Vertical scale denotes GC p to be used with appropriate q z or q h. Horizontal scale denotes effective wind area A, in square feet (square meters). Plus and minus signs signify pressures acting toward and away from the surfaces, respectively. Use qz with positive values of GC p and q h with negative values of GC p.
Each component shall be designed for maximum positive and negative pressures. Coefficients are for roofs with angle θ ≤ 10°. For other roof angles and geometry, use GC p values from Fig. 30.4-2A, B and C and attendant q h based on exposure defined in Section 26.7. If a parapet equal to or higher than 3 ft (0.9m) is provided around the perimeter of the roof with θ ≤ 10°, Zone 3 shall be treated as Zone 2.
Notation: a: 10 percent of least horizontal dimension, but not less than 3 ft (0.9 m). H: Mean roof height, in feet (meters), except that eave height shall be used for θ ≤ 10°.
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Z: height above ground, in feet (meters). Θ: Angle of plane of roof from horizontal, in degrees.
P = q(GC p) - q i(GC pi) (lb/ft 2) (N/m 2) (30.6-1) where q = q z for windward walls calculated at height z above the ground q = q h for leeward walls, side walls, and roofs evaluated at height h q i = q h for windward walls, side walls, leeward walls, and roofs of enclosed buildings and for negative internal pressure evaluation in partially enclosed buildings q i = q z for positive internal pressure evaluation in partially enclosed buildings where height z is defined as the level of the highest opening in the building that could affect the positive internal pressure. For positive internal pressure evaluation, q i may conservatively be evaluated at height h (q i = q h) (GC p) = external pressure coefficients given in: - Fig. 30.6-1 for walls and flat roofs - Fig.
27.4-3, footnote 4, for arched roofs - Fig. 30.4-7 for domed roofs - Note 6 of Fig.
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30.6-1 for other roof angles and geometries (GC pi) = internal pressure coefficient given in Table 26.11-1 q and q i shall be evaluated using exposure defined in. EXCEPTION: In buildings with a mean roof height h greater than 60 ft ( m) and less than 90 ft ( m), (GC p) values from Figs.
30.4-1 through 30.4-6 shall be permitted to be used if the height to width ratio is one or less. User Note: Use Part 3 of for determining wind pressures for C&C of enclosed and partially enclosed buildings with h 60 ft.
Having roof shapes as specified in the applicable figures. These provisions are based on the directional procedure with wind pressures calculated from the specified equation applicable to each building surface. The provisions of Section 30.7 are applicable to an enclosed building having a mean roof height h ≤ 160 ft. Autodesk motionbuilder 2013 crack download. (48.8 m) with a flat roof, gable roof, hip roof, monoslope roof, or mansard roof. The steps required for the determination of wind loads on components and cladding for these building types are shown in Table 30.7-1.
Table 30.7-1 Steps to Determine C&C Wind Loads for Enclosed Building with h ≤ 160 ft Step 1: Determine risk category of building, see Table 1.5-1 Step 2: Determine the basic wind speed, V, for applicable risk category,see Figure 26.5-1A, B, or C Step 3: Determine wind load parameters:. Exposure category B, C, or D, see Section 26.7 Step 4: Enter Table 30.7-2 to determine pressure on walls and roof, p, using Eq. Roof types are. Flat roof (θ.
H = mean roof height (ft) V = Basic wind speed (mph) Components and Cladding - Part 4 h ≤ 160 ft Table 30.7-2 C & C Effective Wind Area C&C Wall and Roof Pressures Enclosed Buildings Reduction Factors Effective Wind Area Roof Form Sign Pressure Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 Flat Flat Minus Plus D NA D NA D NA C D E D Gable, Mansard Gable, Mansard Minus Plus B B C B C B C D E D Hip HIp Minus Plus B B C B C B C D E D Monoslope Monoslope Plus Minus A C B C D C C D E D Overhangs All A A B NA NA Table 30.7-2 Components and Cladding - Part 4 Exposure C C&C V = 110-120 mph h = 15-80 ft. Table 30.7-2 Components and Cladding - Part 4 Exposure C C&C V = 130-150 mph h = 15-80 ft. Table 30.7-2 Components and Cladding - Part 4 Exposure C C&C V = 160-200 mph h = 15-80 ft. Table 30.7-2 Components and Cladding - Part 4 Exposure C C&C V = 110-120 mph h = 90-160 ft. Table 30.7-2 Components and Cladding - Part 4 Exposure C C&C V = 130-150 mph h = 90-160 ft. Table 30.7-2 Components and Cladding - Part 4 Exposure C C&C V = 160-200 mph h = 90-160 ft. Design wind pressures on the designated zones of walls and roofs surfaces shall be determined from Table 30.7-2 based on the applicable basic wind speed V, mean roof height h, and roof slope 8.
Tabulated pressures shall be multiplied by the exposure adjustment factor (EAF) shown in the table if exposure is different than Exposure C. Pressures in Table 30.7-2 are based on an effective wind area of 10 ft 2 (0.93 m 2). Reductions in wind pressure for larger effective wind areas may be taken based on the reduction multipliers (RF) shown in the table. Pressures are to be applied over the entire zone shown in the figures. Final design wind pressure shall be determined from the following equation.
Design wind pressures on parapet surfaces shall be based on wind pressures for the applicable edge and comer zones in which the parapet is located, as shown in Table 30.7-2, modified based on the following two load cases:. Load Case A shall consist of applying the applicable positive wall pressure from the table to the front surface of the parapet while applying the applicable negative edge or comer zone roof pressure from the table to the back surface.
Load Case B shall consist of applying the applicable positive wall pressure from the table to the back of the parapet surface and applying the applicable negative wall pressure from the table to the front surface. Pressures in Table 30.7-2 are based on an effective wind area of 10 sf. Reduction in wind pressure for larger effective wind area may be taken based on the reduction factor shown in the table. User Note: Part 4 of Chapter 30 is a simplified method for determining wind pressures for C&C of enclosed and partially enclosed buildings with h ≤ 160 ft. Having roof shapes as specified in the applicable figures.
These provisions are based on the directional procedure from Part 3 with wind pressures selected directly from a table and adjusted as applicable. Pressures are to be applied to the parapet in accordance with Fig. The height h to be used with Fig. 30.7-1 to determine the pressures shall be the height to the top of the parapet. Determine final pressure from Equation 30.7-1. Components and Cladding - Part 4 h ≤ 160 ft Figure 30.7-1 Parapet Wind Loads Application of Parapet Wind Loads Enclosed Simple Diaphragm Building Windward Parapet Load Case A. Windward parapet pressure (p 1) is determined using the positive wall pressure (p 5) zones 4 or 5 from Table 30.7-2.
Leeward parapet pressure (p 2) is determined using the negative roof pressure (p 7) zones 2 or 3 from Table 30.7-2. Leeward Parapet Load Case B. Windward parapet pressure (p 3) is determined using the positive wall pressure (p 5) zones 4 or 5 from Table 30.7-2. Leeward parapet pressure (p 4) is determined using the negative wall pressure (p 6) zones 4 or 5 from Table 30.7-2. Design wind pressures on roof overhangs shall be based on wind pressures shown for the applicable zones in Table 30.7-2 modified as described herein.
For Zones 1 and 2, a multiplier of 1.0 shall be used on pressures shown in Table 30.7-2. For Zone 3, a multiplier of 1.15 shall be used on pressures shown in Table 30.7-2. Pressures in Table 30.7-2 are based on an effective wind area of 10 sf. Reductions in wind pressure for larger effective wind areas may be taken based on the reduction multiplier shown in Table 30.7-2.
Pressures on roof overhangs include the pressure from the top and bottom surface of overhang. Pressures on the underside of the overhangs are equal to the adjacent wall pressures. Refer to the overhang drawing shown in Fig. Determine final pressure from Equation 30.7-1. Components and Cladding - Part 4 h ≤ 160 ft Figure 30.7-2 Roof Overhang Wind Loads Application of Overhang Wind Loads Enclosed Simple Diaphragm Building P ovh = 1.0 x roof pressure p from tables for edge Zones 1, 2 P ovh = 1.15 x roof pressure p from tables for comer Zone 3 Notes:.
P ovh = roof pressure at overhang for edge or corner zone as applicable from figures in roof pressure table. P ovh from figures includes load from both top and bottom surface of overhang. Pressure p s at soffit of overhang can be assumed same as wall pressure p w. The provisions of Section 30.8 are applicable to an open building of all heights having a pitched free roof, monosloped free roof, or troughed free roof. The steps required for the determination of wind loads on components and cladding for these building types is shown in Table 30.8-1. P = q hGC N (30.8-1) where q h = velocity pressure evaluated at mean roof height h using the exposure as defined in Section 26. 7.3 that results in the highest wind loads for any wind direction at the site G = gust-effect factor from C N = net pressure coefficient given in: - Fig.
30.8-1 for monosloped roof - Fig. 30.8-2 for pitched roof - Fig. 30.8-3 for troughed roof Net pressure coefficients C N include contributions from top and bottom surfaces. All load cases shown for each roof angle shall be investigated. Plus and minus signs signify pressure acting toward and away from the top surface of the roof, respectively.
P = q p( GC p) - ( GC pi) (30.9-1) where q p = velocity pressure evaluated at the top of the parapet (GC p) = external pressure coefficient given in - Fig. 30.4-1 for walls with h ≤ 60 ft ( 48.8 m) - Figs. 30.4-2A to 30.4-2C for flat roofs, gable roofs,and hip roofs - Fig.
30.4-3 for stepped roofs- Fig. 30.4-4 for multispan gable roofs - Figs.
30.4-5A and 30-5B for monoslope roofs - Fig. 30.4-6 for sawtooth roofs - Fig. 30.4-7 for domed roofs of all heights - Fig. 30.6-1 for walls and flat roofs with h 60 ft(18.3 m)- Fig. 27.4-3 note 4 for arched roofs (GC pi) = internal pressure coefficient from Table 26.11-1, basedon the porosity of the parapet envelope Two load cases, see Fig.
30.9-1, shall be considered:. Load Case A: Windward parapet shall consist of applying the applicable positive wall pressure from Fig. 30.4-1 h ≤ 60 ft (18.3 m) or Fig. 30.6-1 h 60 ft (18.3 m) to the windward surface of the parapet while applying the applicable negative edge or corner zone roof pressure from Figs. 30.4-2 (A, B, or C), 30.4-3, 30.4-4, 30.4-5 (A or B), 30.4-6, 30.4-7, Fig.
27.4-3 note 4, or Fig. 30.6-1 h 60 ft (18.3 m) as applicable to the leeward surface of the parapet. Load Case B: Leeward parapet shall consist of applying the applicable positive wall pressure from Fig.
30.4-1 h ≤ 60 ft (18.3 m) or Fig. 30.6-1 h 60 ft (18.3 m) to the windward surface of the parapet, and applying the applicable negative wall pressure from Fig. 30.4-1 h ≤ 60 ft (18.3 m) or Fig.
30.6-1 h 60 ft (18.3 m) as applicable to the leeward surface. Edge and corner zones shall be arranged as shown in the applicable figures. (GC p) shall be determined for appropriate roof angle and effective wind area from the applicable figures. If internal pressure is present, both load cases should be evaluated under positive and negative internal pressure. The steps required for the determination of wind loads on component and cladding of parapets are shown in Table 30.9-1.
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User Note: Use Part 6 of Chapter 30 for determining wind pressures for C&C on roof overhangs and parapets of buildings. These provisions are based on the directional procedure with wind pressures calculated from the specified equation applicable to each roof overhang or parapet surface. Table 30.9-1 Steps to Determine C&C Wind Loads for Parapets Step 1: Determine risk category of building, see Table 1.5-1 Step 2: Determine the basic wind speed, V, for applicable risk category,see Figure 26.5-1A, B, or C Step 3: Determine wind load parameters:. Wind directionality factor, K d, see Section 26.6 and Table 26.6-1. Exposure category B, C, or D, see Section 26.7. Topographic factor, K zt, see Section 26.8 and Fig.
26.8-1. Enclosure classification, see Section 26.10. Internal pressure coefficient, (GC pi), see Section 26.11 and Table 26.11-1 Step 4: Determine velocity pressure exposure coefficient, K h, at top of the parapet, see Table 30.3-1 Step 5: Determine velocity pressure, q p, at the top of the parapet using Eq. 30.3-1 Step 6: Determine external pressure coefficient for wall and roof surfaces adjacent to parapet, (GC p). Walls with h ≤ 60 ft., see Fig. 30.4-1. Flat, gable, and hip roofs, see Figs.
30.4-2A to 30.4-2C. Stepped roofs, see Fig. 30.4-3. Multispan gable roofs, see Fig. 30.4-4. Monoslope roofs, see Figs. 30.4-5A and 30.4-5B.
Sawtooth roofs, see Fig. 30.4-6. Domed roofs of all heights, see Fig. 30.4-7. Walls and flat roofs with h 60 ft., see Fig. 30.6-1.
Arched roofs, see note 4 of Fig. 27.4-3 Step 7: Calculate wind pressure, p, using Eq. 30.9-1 on windward andleeward face of parapet, considering two load cases (Case A and Case B) as shown in Fig. Components and Cladding - Part 6 All Building Heights Figure 30.9-1 Parapet Wind Loads C & C Parapet Wind Loads All Building Types Windward Parapet Load Case A. Windward parapet pressure (p 1) is determined using the positive wall pressure (p 5) zones 4 or 5 from the applicable figure. Leeward parapet pressure (p 2) is detennined using the negative roof pressure (p 7) zones 2 or 3 from the applicable figure. Leeward Parapet Load Case B.
Windward parapet pressure (p 3) is determined using the positive wall pressure (p 5) zones 4 or 5 from the applicable figure. Leeward parapet pressure (p 4) is determined using the negative wall pressure (p 6) zones 4 or 5 from the applicable figure. P = q h( GC p) - ( GC pi) (lb/ft 2) (N/m 2) (30.10-1) where q h = velocity pressure from Section 30.3.2 evaluated at mean roof height h using exposure defined in Section 26.7.3 (GC p) = external pressure coefficients for overhangs given in Figs. 30.4-2A to 30.4-2C (flat roofs, gable roofs, and hip roofs), including contributions from top and bottom surfaces of overhang. The external pressure coefficient for the covering on the underside of the roof overhang is the same as the external pressure coefficient on the adjacent wall surface, adjusted for effective wind area,determined from Figure 30.4-1 or Figure 30.6-1 as applicable (GC pi) = internal pressure coefficient given in Table 26.11-1 The steps required for the determination of wind loads on components and cladding of roof overhangs are shown in Table 30.10-1. Table 30.10-1 Steps to Determine C&C Wind Loads for Roof Overhangs Step 1: Determine risk category of building, see Table 1.5-1 Step 2: Determine the basic wind speed, V, for applicable risk category, see Figure 26.5-1A, B, or C Step 3: Determine wind load parameters:. Wind directionality factor, K d, see Section 26.6 and Table 26.6-1.
Exposure category B, C, or D, see Section 26.7. Topographic factor, K zt, see Section 26.8 and Fig. 26.8-1.
Enclosure classification, see Section 26.10. Internal pressure coefficient, (GC pi), see Section 26.11 and Table 26.11-1 Step 4: Determine velocity pressure exposure coefficient, K h, see Table 30.3-1 Step 5: Determine velocity pressure, q h, at mean roof height h using Eq. 30.3-1 Step 6: Determine external pressure coefficient, (GC p), using Figs. 30.4-2A through C for flat, gabled, and hip roofs. Step 7: Calculate wind pressure, p, using Eq.
Refer to Figure 30.10-1 Components and Cladding All Building Heights Figure 30.10-1 Wind Loading - Roof Overhangs C & C Wind Load on Roof Overhangs All Building Types Notes:. Net roof pressure p ovh on roof overhangs is determined from interior, edge or comer zones as applicable from figures. Net pressure p ovh from figures includes pressure contribution from top and bottom surfaces of roof overhang.
Positive pressure at roof overhang soffit p s is the same as adjacent wall pressure p w. The components and cladding pressure on each wall of the rooftop structure shall be equal to the lateral force determined in accordance with divided by the respective wall surface area of the rooftop structure and shall be considered to act inward and outward. The components and cladding pressure on the roof shall be equal to the vertical uplift force determined in accordance with divided by the horizontal projected area of the roof of the rooftop structure and shall be considered to act in the upward direction.
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