sbc chp 15 wind loading

1604.8 - 1606.2.2.3

of the rails acting in either direction normal to the runwayrails and shall be distributed with due regard for lateralstiffness of the structure supporting these rails. The longitudinal force shall, if not otherwise specified, be taken as10% of the maximum wheel loads of the crane applied atthe top of the rail.

1604.8 Supports for walkway. Where walkways are to beinstalled above ceilings, supports shall be designed to carry aload of 200 lb (890 N) occupying a space 2 II2 sq ft (0.23m2), so placed as to produce maximum stresses in the affected members.

1604.9 Sidewalks. Sidewalks shall be designed to carryeither a uniformly distributed load of 200 psf (9.6 kPa) or aconcentrated load of 8,000 lb (35.6 kN) on a space 2 II2square feet (0.58 m2) and placed in any position, whicheverwill produce the greater stresses. This does not apply to sidewalks on grade.

SECTION 1605SNOW LOADS

Ground snow loads shall be as set forth in Figure 1605.Design roof snow loads shall be calculated in compliancewith provisions in Section 7, Snow Loads, of ASCE 7.

SECTION 1606WIND LOADS

1606.1 Applications. All buildings, structures and partsthereof shall be designed to withstand the appropriate windloads prescribed herein. Decreases in wind loads shall not bemade for the effect of shielding by other structures. Windpressures shall be assumed to act normal to the surfaces considered.

1606.1.1 Determination of wind forces. Wind forces onevery building or structure shall be determined by the provisions of ASCE 7.

Exceptions:1. Provisions of 1606.2 shall be permitted for build

ings 60 ft (18.3 m) high or less.2. Wind tunnel tests together with applicable sec

tions of 1606.2.3. Provisions of SBCCI SSTD 10 shall be permitted

for applicable Group R2 and R3 buildings.4. Provisions of AF&PA Wood Frame Construction

Manual for One and Two-Family Dwellings 1995 SBC High Wind Edition ©1996 shall bepermitted for applicable wood framed buildingsof Group R3 occupancy.

5. ANSIINAAMM FP 1001 Specification forDesign Loads of Metal Flagpoles.

1606.1.2 Limitations1606.1.2.1 Mixing of provisions from ASCE 7 and1606.2 shall not be permitted.

216

1606.1.2.2 Provisions of 1606.2 do not apply to buildings or structures having unusual geometric shapes,response characteristics or site locations for whichchanneling effects or buffeting in the wake of upwindobstructions may warrant special consideration. Forthese cases, wind loads shall be based on wind tunneltests or nationally recognized data.

1606.2 Buildings 60 feet high or less1606.2.1 Scope. Procedures in 1606.2 shall be used fordetermining and applying wind pressures in the design ofbuildings with flat, single sloped, hipped and gableshaped roofs whose mean roof heights exceed neither 60ft (18.3 m) nor the least horizontal dimension of the building.

1606.2.2 Wind pressures1606.2.2.1 Structural members, cladding, fasteners andsystems providing for· the structural integrity of thebuilding shall be designed for the velocity pressuresfrom Table 1606.2A using Figure 1606, multiplied bythe appropriate pressure coefficient from Tables1606.2B and 1606.2C and Figures 1606.2C to 1606.2Eand by the appropriate use factor from Table 1606.Coefficients given in 1606.2 include a gust factor andthus do not correspond to coefficients used in manyother sources. Mixing of coefficients and dynamicpressures from different sources shall not be permitted.

TABLE 1606USE FACTORS FOR BUILDINGS AND OTHER STRUCTURES

NATURE OF OCCUPANCY USE FACTOR

All buildings and structures except those listed below 1.0

Buildings and structures where the occupantload is 300 or more in anyone room. 1.15Buildings and structures designated as essential

facilities, including, but not limited to: 1.15(l) Hospital and other medical facilities having

surgery or emergency treatment areas(2) Fire or rescue and police stations(3) Primary communication facilities and disaster

operation centers(4) Power stations and other utilities required in an

emergency

Buildings and structures that represent a low hazard tohuman life 'in the event of failure, such as agricultural 0.9buildings, certain temporary facilities, and minor storagefacilities

1606.2.2.2 Members that act as both part of the mainwind force resisting system and as components andcladding shall be designed for separate load cases.

1606.2.2.3 No part (component, cladding or fastener)of a building shall be designed for less than 10 psf (479Pa) acting in either direction normal to the surface.

STANDARD BUILDING CODE© 1997

• • e(fj

i!zc»JJclDc::rczG)

00cm@

PX/'-~rt~!~~"m~,)~f~TT<1tr3ro['N, /~\I----url I=tf~~ ('lll/')-"(,D(,D

(4f:).....(~)

(5~)

i~Vfb~(1~go)

(1\00) , '25

i~b

In CS 8ro8S, slt.-pecffle Case Studies are required toestablish ground snow loads. Extreme local Yarlatrons::: ~l:su:cc:.r.~owloads In these arel!S preclude mapping

Numbers In P..8l'1Jnthoses nl:PI'88IH1't the up-per eleVBtlonlimits In feet for the grounersnow IOlld values presented'b.low. SlbNIpllClflc case studies are reqUired to establishground snow loads at elevations not covered.

To convert Iblsq ft to kNm2, multiply by 0.0479.

To convert feet to met91'S, multiply by 0.3048

I ., I I I Io 100 200 300 miles

I\)-".....

FIGURE 1605GROUND SNOW LOADS, Pg , FOR THE UNITED STATES (POUNDS PER SQUARE FOOT)

III1II1IIIII1111111111111I111111111111111111111111111111.111111111111111111111111111111111111111111111111111111'1111111111111111111111111111111111111111111111111111III11111IIIII111I11111111111111111111111111111111111111I111I11111I111111111111111111111111111111111111111111I1I1

"T1

15c::Dm.....O'loen

FIGURE 1606

80

80

III BASIC WIND SPEED 70 MPH

~ SPECIAL WIND REGION

GULF OF MEXICO

NOTES:1. VALUES ARE FASTEST-MILE SPEED AT 33 FT (10 M) ABOVE

GROUND FOR EXPOSURE CATEGORY C AND ASSOCIATEDWITH AN ANNUAL PROBABILITY OF 0.02. .

2. LINEAR INTERPOLATION BETWEEN WIND SPEED CONTOURSIS ACCEPTABLE.

3. CAUTION IN USE OF WIND SPEED CONTOURS IN MOUNTAINOUSREGION OF ALASKA IS ADVISED.

FIGURE 1606BASIC WIND SPEEDS FOR 50-YEAR MEAN RECURRENCE INTERVAL

(ALEUTIAN ISLANDS, VIRGIN ISLANDS AND PUERTO RICO SHALL USE A BASIC WIND SPEED OF 110 MPH)

For SI: 1 mph =0.447 mls.

218 STANDARD BUILDING CODE© 1997

1606.2.2.4 The wind load used in the design of themain wind force resisting system for buildings shallnotbe less than 10 psf multiplied by the area of thebuilding projected on a vertical plane that is perpendicular to the wind direction.

1606.2.3 Definitions. For definitions, see Chapter 2.

1606.2.4 Main wind force resisting system (MWFRS).Pressure coefficients GCp for all wind loading actionsarising from combining loads acting simultaneously onmore than one surface shall be determined by 1606.2.4.

1606.2.4.1 End zones. The width of "X" end zones asshown in Figures 1606.2B1 and 1606.2B2 shall betwice the value of "Z" determined in 1606.2.5.1. Forframed buildings whose end bay spacings are greaterthan or equal to "X" the difference in end zone andinterior zone loading can be allocated entirely to theend frame.

1606.2.4.2, Applicability of coefficients. Pressurecoefficient GCp for the main wind force resisting system shall be taken from Tables 1606.2B or 1606.2Cand applied with consideration for the torsional effectin each individual load case, as shown in Figures1606.2Bl and 1606.2B2 and as specified in 1606.2.2.Where more than one load case exists, buildings shallbe designed for all load cases.

1606.2.4.3 Overhang coefficients. The pressure coefficients GCp to be used for the effects of roof overhangs on MWFRS for each of the load cases and windward and leeward surfaces shall be as indicated inTable 1606.2D. Roof overhang members shall bedesigned in accordance with 1606.2.5.

1606.2.5 Components and cladding. Pressure coefficients GCp for wind loading actions on components andcladding shall be determined from Figures 1606.2C,1606.2D and 1606.2E, based on effective wind area.

1606.2.5.1 Edge strips. The width of the edge strips"Z" for walls and roofs shall be determined by thesmaller of 10% of the least horizontal dimension of thebuilding or 40% of the eave height, but not less than thelarger of 4% of the least horizontal dimension of thebuilding or 3 ft (914 mm).

1606.2.5.2 Walls.1. Pressure coefficients GCp for components and

cladding of walls shall be taken from Figure1606.2C according to their effective wind areasand applied to the corresponding regions of thebuilding as shown in Figure 1606.2C.

2. Coefficients taken from Figure 1606.2C may bereduced 10% if the angle of the roof is no greaterthan 10 degrees.


1606.2.2.4 -1606.3.1

1606.2.5.3 Gable and hip roofs. Pressure coefficientsGCp for components and cladding or roofs shall betaken from Figure 1606.2D and 1606.2E. Pressurecoefficients for roof angles greater than 45 degree(0.785 rad) shall be based on nationally recognizeddata.

1606.2.5.4 Monoslope roofs. Pressure coefficientsGCp for monoslope roofs shall be taken from Figure1606.2D for roof slopes between 0 degrees and 3degrees (0 and 0.052 rad), and from Figures 1606.2Fand 1606.2G for roof slopes greater than 3 degrees(0.052 rad).

1606.2.6 Simplified wind loads for buildings with vertically spanning walls. Wind loads for enclosed buildingswith vertically spanning walls whose main wind forceresisting system consists of floor and roof diaphragms thatare laterally supported by shear walls, braced frames ormoment frames shall be permitted to be designed in accordance with this section. Structural members, cladding, fasteners and systems providing for the structural integrity ofthe building shall be designed for the velocity pressuresfrom Table 1606.2A using Figure 1606, multiplied by theappropriate pressure coefficient from Table 1606.2E andFigures 1606.2C to 1606.2E and by the appropriate usefactor from Table 1606.

1606.2.6.1 Main wind force resisting system. All elements and connections of the main wind force resistingsystem shall be designed for vertical and horizontalloads based on the combined leeward and windwardwall and roof coefficients GCp as given in Table1606.2E. The design wind load shall be applied nonconcurrently to each major axis of the structure. Thewidth of the end zone shall be determined from1606.2.4.1.

Wall elements subjected to wind loads which also support roof framing members shall be considered part ofthe main wind force resisting system. These elementsshall be designed for the interaction of vertical and horizontal wind loads or have independent resistancemechanisms for vertical load and horizontal load. Thehorizontal load shall be based on GCp = ± 0.95 for endzones and GCp =± 0.70 for interior zones.

1606.2.6.2 Components and cladding. All wall androof framing including cladding and connections ofthese elements shall be designed using pressure coefficients GCp determined from Figures 1606.2C,1606.2D, and 1606.2E.

1606.3 Roof systems1606.3.1 Roof deck. The roof deck shall be designed towithstand the wind pressures determined under 1606.2 forbuildings 60 ft (18.3 m) or less in height or ASCE 7 forbuildings of any height.

219

1606.3.2· TABLE 1606.2A

1606.3.2 Roof coverings. Roof coverings shall complywith 1606.3.1. Rigid tile roof coverings that are air-permeable and installed over a roof deck shall be permitted tobe designed in accordance with 1606.3.3.

1606.3.3 Rigid tile. Wind loads on rigid tile roof coverings shall be determined as the lifting moment Ma. Thelifting moment shall be determined in accordance with thefollowing formula:

7. Maximum thickness of the tail of the roof tile shallnot exceed 1.3 inches (33 mm).

8. Roof tiles using mortar set or adhesive set systemsshall have at least 2/3 of the tile's area free of mortar or adhesive contact.

TABLE 1606.3.3LIFT COEFFICIENTS FOR RIGID ROOF TILE

110

24.725.225.626.126.526.827.628.328.929.630.131.031.532.733.834.935.836.7

20.420.821.221.521.922.222.823.423.924.424.925.626.027.028.028.829.630.4

0.20

16.616.917.217.417.718.018.518.919.419.820.220.721.121.922.723.324.024.6

80

FASTEST MILE WIND SPEED, (V)2 IN MPH(FROM FIGURE 1606)

90 100

10.0 13.I10.2 13.310.4 13.610.5 13.810.7' 14.010.9 14.211.2 14.61l.5 15.011.7 15.312.0 15.612.2 15.912.5 16.412.8 16.713.3 17.313.7 17.914.1 18.414.5 19.014.9 19.4

ROOFING MATERIAL

Concrete & clay tile

MEAN ROOF ---------------HEIGHT H3 (ft) 70

2. V = Fastest mile wind speed in miles per hour determined fromFigure 1606.

3. H = Mean height of roof above ground or 15 ft whichever is greater.Eave height may be substituted for mean roof height if roof angle "a"is not more than 10 degrees.

q = 0.00256 V2

( ~ ) zn

TABLE 1606.2AVELOCITY PRESSURE (q)1 (PSF)

0-151617181920222426283033354045505560

For SI: I mph = 0.447 mis, I psf = 47.8803 Pa, 1 ft = 0.305 m.Notes:

I. A single value for velocity pressure (q) is used for the entire building.

where:Ma = aerodynamic uplift moment (ft-lb) acting to

raise the tail of the tile.qh = wind velocity pressure (psf) determined from

Table 1606.2A.CL = lift coefficient determined from Table

1606.3.3 or by testing in accordance with1707.5.

b =exposed width (ft) of the roof tile.L =length (ft) of the roof tile.La =moment arm (ft) from the axis of rotation to

the point of uplift on the roof tile. The point ofuplift shall be taken at 0.76 L from the head ofthe tile and the middle of the exposed width.For roof tiles with nails or screws (with orwithout a tail clip), the axis of rotation shall betaken as the head of the tile for direct deckapplications and as the top edge of the battenfor battened applications. For roof tiles fastened only by a nail or screw along the side ofthe tile, the axis of rotation shall be determinedby testing. For roof tiles installed with battensand fastened only by a clip near the tail of thetile, the moment arm shall be determinedabout the top edge of the batten with consideration given for the point of rotation of the tilesbased on straight bond or broken bond and thetile profile.

GCp = roof coefficient for each applicable zone determined from Figure 1606.2E. Roof coefficientshall not be adjusted for internal pressure.

Concrete and clay roof tiles complying with the followinglimitations shall be designed to withstand the wind loadsprescribed in this section.

1. The roof tiles shall be either loose laid on battens ormechanically fastened or mortar set or adhesive set.

2. The roof tiles shall be installed on solid sheathingwhich has been designed as components andcladding in accordance with 1606.2.3.3.

3. An underlayment shall be installed in accordancewith 1509.7.

4. The tile shall be single lapped interlocking with aminimum head lap of not less than 2 inches (51mm).

5. The length of the tile shall be between 1.0 and 1.75ft (305 and 533 mm).

6. The exposed width of the tile shall be between 0.67and 1.25 ft (203 and 381 mm).

§..


------ -------------------

TABLE 1606.2B - TABLE 1606.2C

TABLE 1606.2BGC COEFFICIENTS FOR MWFRS

PROVIDING RESISTANCE IN TRANSVERSE DIRECTION1

END ZONE COEFFICIENTS INTERIOR ZONE COEFFICIENTSROOF NOTESANGLE5 1E 2E 3E 4E 2 3 4

OJ) 0< a s 10° 2 +.50 -1.4 -.80 -.70 +.25 -1.0 -.65 -.55"~ 3 +.90 -1.0 -.40 -.30 +.65 -.60 -.25 -.15::l 10° < a S 20° 2 +.70 -1.4 -1.0 -.95 +.40 -1.0 -.75 -.70~

-0 3 +1.1 -1.0 -.60 -.55 +.80 -.60 -.35 -.30<l)

~ 20° < as 30° 2 +.70 -1.0 -1.0 -.95 +.40 -.75 -.75 -.70U 3 +1.1 -.60 -.60 -.55 +.80 -.35 -.35 -.30"~

30° < a S 45° 2 +.60 +.10 -.80 -.75 +.45 +.05 -.70 -.653 +1.0 +.50 -.40 -.35 +.85 +.45 -.30 -.254 -.75 -1.4 -.80 -.75 -.70 -1.0 -.65 -.70

a =90° 5 2 +.58 +.58 -.74 -.74 +.43 +.43 -.62 -.623 +.98 +.98 -.34 ~.34 +.83 +.83 -.22 -.224 -.74 -1.4 -.80 -.74 -.71 -.98 -.62 -.71

0< a s 10° 2 +.10 -1.8 -1.2 -1.1 -.15 -1.4 -1.1 -.95-0 3 +1.0 -.90 -.30 -.20 +.75 -.50 -.15 -.05~

10° < a s 20° 2 +.30 -1.8 -1.4 -1.4 0.0 -1.40 -1.2 -1.1U

3 +1.2 -.50 -.45 +.90 -.50" -.90 -.25 -.20~

b 20° < a s 30° 2 +.30 -1.4 -1.4 -1.4 0.0 -1.2 -1.2 -1.1

'" 3 +1.2 -.50 -.50 -.45 +.90 -.25 -.25 -.20.~

30° < as 45° 2 +.20 -.30 -1.2 -1.2 -.05 -.35 -1.1 -1.10..

3 +1.1 +.60 -.30 -.25 +.95 +.55 -.20 -.154 -1.2 -1.8 -1.2 -1.2 -1.1 -1.4 -1.1 -1.1

a =90° 5 2 +.28 +.28 -1.0 -1.0 +.03 +.03 -1.0 -1.03 +1.1 +1.1 -.24 -.24 +.93 +.93 -.12 -.124 -1.1 -1.8 -1.2 -1.1 -1.1 -1.4 -1.0 -1.1

" 0< as 10° 6,11 + 1.8 -.70 -.70 0 +1.8 -.70 -.70 0<l)0.-0 7,11 + 1.8 .-.30 -.80 0 +1.8. -.30 -.80 0

""' 10° < a s 25° 6,11 + 1.8 -.70 -.70 0 +1.8 -.70 -.70 0'£<l) 7,11 + 1.8 +.70 -.70 0 +1.8 +.70 -.70 00..E 7,11 + 1.8 +.20 -.90 0 +1.8 +.20 -.90 00u 25° < a s 45" 6,11 + 1.8 -.70 -.70 0 +1.8 -.70 -.70 0

7,11 + 1.8 +2.0 +.30 0 +1.8 +2.0 +.30 0

See notes following Figure 1606.2B2

TABLE 1606.2CGC COEFFICIENTS FOR MWFRS

PROVIDING RESISTANCE IN LONGITUDINAL DIRECTION(ALL ROOF ANGLESp

END ZONE INTERIOR ZONECOEFFICIENTS COEFFICIENTS

BUILDINGCLASSIFICATION NOTES 2E 3E 5E 6E 2 3 5 6

Enclosed 8,9 -1.40 -0.80 +0.50 -0.70 -1.00 -0.65 +0.25 -0.558,10 -1.00 -0.40 +0.90 -0.30 -0.60 -0.25 +0.65 -0.15

Partially 8,9 -1.80 -1.20 +0.10 -1.10 -1.40 -1.05 -0.15 -0.95Enclosed 8,10 -0.90 -0.30 +1.00 -0.20 -0.50 -0.15 +0.75 -0.05

6,11 -0.70 -0.70 +1.8 0.00 -0.70 -0.70 +1.8 0.00Open 7,11 -0.30 -0.80 +1.8 0.00 -0.30 -0.80 +1.8 0.00

See notes following Figure 1606.2B2

STANDARD BUILDING CODE© 1997 221

FIGURE 1606.281 • TA8LE 2606.282

LOAD CASE A: WINDS GENERALLY PERPENDICULAR TO RIDGE

4

"

WIND DIRECTION RANGE

LOAD CASE 81: WINDS GENERALLY PARALLEL TO RIDGE

4

"4E

" 2E

< 8

H 1E

. B~,>-)?

~WIND DIRECTION RANGE

FIGURE 1606.281APPLICATION OF COEFFICIENTS FOR PRIMARY STRUCTURAL SYSTEMS PROVIDING RESISTANCE IN TRANSVERSE DIRECTION

(POSITIVE SIGN INDICATES INWARD ACTING PRESSURE)


6E



6

6E


FIGURE 1606.282APPLICATION OF COEFFICIENTS FOR PRIMARY STRUCTURAL SYSTEMS PROVIDING RESISTANCE IN LONGITUDINAL DIRECTION

(POSITIVE SIGN INDICATES INWARD ACTING PRESSURE)

222 STANDARD 8UILDING CODE@1997

TABLE 1606.20

Notes to accompany Tables 1606.28, 1606.2C and Figures 1606.281, 1606.282:

I. The building must be designed for all wind directions. Transverse and longitudinal directions denote directions perpendicular and parallel to ridge,respectively. For buildings having flat roofs, a ridge line normal to the wind direction shall be assumed at the mid-length dimension of the roof for thedirection considered. Each corner must be considered in turn as the windward corner shown in the figures. For all roof slopes, Load Case A and LoadCases B2 and B3 are required as separate conditions to generate the wind actions, including torsion, to be resisted by the structural systems. If the roofslope is 30 degrees or more, a third loading condition B I is also required.

2. Load Case A with internal pressure; wind generally perpendicular to ridge.3. Load Case A with internal suction; wind generally perpendicular to ridge.4. Load Case B1 with internal pressure; wind generally parallel to ridge.5. For roof angles, 450 < a < 900

, the coefficient OCp may be obtained by linear interpolation.6. Uplift equal on both roof surfaces.7. Unbalanced loading on roof surfaces.8. Load Case B2 with internal pressure; wind generally parallel to ridge.9. Load Case B3 with internal pressure; wind generally parallel to ridge.10. Load Case B3 with internal suction; wind generally parallel to ridge.II. Coefficient to be applied to the windward side of the effective solid area of every vertical surface exposed to the wind.12. For buildings whose widths are greater than 5 times their eave heights, coefficient 2 in Table 1606.2B, when negative, shall be applied to the windward _

slope of the roof starting at the windward eave for a distance of 2 1/2 times the eave height. Coefficient 3 shall be applied to the remainder of the roof.13. Coefficients 2E and 2 in Table 1606.2C shall be applied in accordance with Sections 1606.2.4.1 to the windward portion of the roof starting at its wind

ward edges for a distance of 2 1/2 times the maximum height of the roof. Coefficients 3E and 3 shall be substituted for 2E and 2 respectively for theremainder of the roof.

14. Notations:a: Roof angle from horizontal, in degrees.B: Width of building, in feet.H: Reference height for assessing design pressures given by mean height of roof or 15 feet, whichever is greater. Eave height may be substituted for

mean height when angle of the roof "a" is less than or equal to 10 degrees.N: Number of transverse frames.S: Bay spacing, in feet.X: Zone width defined as 2Z, where Z is edge strip distance defined below. All areas not within end zone are considered interior zones.Z: Edge strip defined as the lesser of 10% of least horizontal dimension of building or 40% of height H but not less than 4% of least horizontal dimen

sion of building and at least 3 ft.0: Ratio of solid area of frame to gross area outlined by frame on vertical plane.

1 degree =0.01745 radFor SI: I ft =0.305 m.

TABLE 1606.20GCp COEFFICIENTS FOR ROOF OVERHANGS

LOADCASE

WINDWARD ROOFOVERHANG

LEEWARD ROOFOVERHANG

Zone GCp Zone GCp

A 2&2E +0.2, -1.5 3 &3E Coefficients givenBl, B2 2E&3E +0.2, -1.5 2&3 in Tables 1606.2BB3 2&2E +0.2, -1.5 3 &3E and 1606.2C

STANDARD BUILDING CODE@1997 223

TABLE 1606.2E - FIGURE 1606.2C

TABLE 1606.2ESIMPLIFIED WIND LOAD COEFFICIENTS GCp

HORIZONTAL1 VERTICAL2

DIRECTIONOF LOAD

Transverse

Longitudinal

End Zone Interior Zone End Zone Interior Zone

ROOF Wall Roof Wall Roof Windward Leeward Windward LeewardANGLE Roof Roof Roof Roof

O:S:a:S:lO° +1.20 -0.60 +0.80 -0.35 -1.40 -0.80 -1.00 -0.65100<a<20° +1.65 -0.40 +1.10 -0.25 -1.40 -1.00 -1.00 -0.7520° < a:S: 30° +1.65 0 +1.10 0 -1.00 -1.00 -0.75 -0.7530° < a:S: 45° +1.35 +0.90 +1.10 +0.75 +0.10 -0.80 +0.05 -0.70all angles +1.20 -0.60 +0.80 -0.35 -1.40 -0.80 -1.00 -0.65

For SI: I degree =0.01745 rad.Notes:

1. Horizontal coefficients:a. Positive sign indicates pressure acting in direction of wind, negative sign indicates pressure acting opposite to direction of wind.b. Roof coefficients are applied to the vertiCal projection of the roof. For buildings with a width to eave height (He) ratio greater than 5, the effective

vertical projection of the roof shall be taken as 2.5 He tan a.2. Vertical coefficients:

a. Positive sign indicates pressure acting downward, negative sign indicates pressure acting upward.b. Roof coefficients are applied to the horizontal projection of the roof.

GC p

-1.8-1.6-1.4-1.2

-1.0-0.8-0.6-0.4-0.2o

0.20.40.60.8

1.01.21.41.61.8

2.0

WALL=

oG

FIGURE 1606.2CWALL COEFFICIENTS, GCp, COMPONENTS AND CLADDING

(ENCLOSED BUILDINGS)Notes:

I. Plus and minus signs signify pressures acting toward and away from the surfaces, respectively.2. Each component shall be designed for maximum positive and negative pressures.3. For partially enclosed buildings, positive coefficients shall be increased by 0.1, negative coefficients shall be increased by 0.4 (in absolute sense).4. Coefficients may be reduced 10% when a:S: 10° (0.175 rad).


FIGURE 1606.2D

r--IIIIIIIIL _

w(!)ClWLLo?i

10 20 50 100200 5001000EFFECTIVE WIND AREA (sq. ft.)

0.2m~0.4

0.6 ALL REGIONS :I

-3.0 r--1~:-:-::=~~"T""1

-2.6=_~0-2.4 F\.~-2.2

-2.0-1.8

GC p -1.6-1.4-1.2

-1.0-0.8-0.6-0.4-0.2o

ROOF=

0)

10 20 50 100 200 500 1000EFFECTIVE WIND AREA (sq. ft.)

0.2m~0.4

0.6 ALL REGIONS :I

-3.0-2.8-2.6-2.4-2.2

-2.0-1.8

-1.2-1.0

-0.8-0.6-0.4-0.2o

FIGURE 1606.2DROOF COEFFICIENTS, GCp, COMPONENTS AND CLADDING1

(ENCLOSED BUILDINGS)0° :s; a :s; 10°

Note:I. Overhang coefficients include contributions from both upper and lower surfaces.


FIGURE 1606.2E

00)

= i=OVERHANG*

==~0 and (9==-= ~;;;;;

==G) and r~=~= -

10 20 50 100 200 50010EFFECTIVE WIND AREA (sq. fl.

ALL REGIONSJ

-3.0-2.8-2.6-2.4-2.2

-2.0-1.8

GC p -1.6-1.4-1.2

-1.0.{J.8.{J.6.{J.4.{J.2o

0.40.6

10"< a:s 30' 0.8

00)

acv==ROOF ==('c

::::=fls l

- - c-G) and (re ==

10 20 5010020050010EFFECTIVE WIND AREA (sq. fl.

ALL REGIONS1

0.40.60.8

-3.0-2.8-2.6-2.4-2.2

-2.0-1.8

GC p -1.6-1.4-1.2

-1.0.{J.8.{J.6.{J.4.{J.2o

000.)

~=~OV~~c S S an

0)~ ;===

10 20 50 100 200 5001

EFFECTNE ~~~~~~~'lft

-2.0-1.8-1.6-1.4-1.2

GC p -1.0-0.8-0.6-0.4.{J.2o

0.830"<a:s45' 1.0

1.8

-2.0E~EEROiQF"3-1.8 -, 8 ,I-- -;::!.,ROOF =

_1'61~1~IClalndll(88

1

'1'111:~:~ - i and 'a

GCp-~~=t=Q.{J.6.{J.4.{J.2

o 10 20 50 100200 5001000

~E~F~FE~C~T~NE~W~I~NID~AR§EA§d§'S~Q"fl.)0.40.6 ALL REGIONS0.8

FIGURE 1606.2EROOF COEFFICIENTS, GCp• COMPONENTS AND CLADDING1

(ENCLOSED BUILDINGS)10°<8::::45°

Note:1. Overhang coefficients include contributions from both upper and lower surfaces.

Notes to Figures 1606.2D and 1606.2E:I. Plus and minus signs signify pressures acting toward and away from the surfaces, respectively.2. Each component shall be designed for maximum positive and negative pressures.3. For partially enclosed buildings, positive coefficients shall be increased by 0.1, negative coefficients shall be increased by 0.4 (in absolute sense).4. For open buildings, roof coefficients in Figures 1606.2D and 2E shall be reduced by 0.2 (in absolute sense).5. Overhang coefficients include contributions from both upper and lower surfaces.6. Notation:

a: Roof angle from horizontal ( ° ).Z: 10% of minimum building width or O.4H, whichever is smaller, but not less than the larger of 4% of the minimum building width or 3 ft.H: Mean roof height, (ft) except that eave height may be used when a :::: 10°.

7. For roof angles greater than 45°, coefficients shall be based on nationally recognized data.


10 20 50 100200 5001000EFFECTIVE WIND AREA (sq. ft.)

-3.4-3.2

-3.0-2.8-2.6 ;;;;;;;;l( s-2.4 t----,..

-2.0-1.8

GC -1.6P -1.4

-1.2

-1.0-0.8-0.6-0.4-0.2

o

o ~ ROOF=

FIGURE 1606.2F - FIGURE 1606.2G

a

[ -{__JlIt-...--- 8 ------<a-il

FIGURE 1606.2FMONOSLOPE ROOF COEFFICIENTS, GCp, COMPONENTS AND CLADDING1, 2

(ENCLOSED BUILDINGS)3° < a ~ 10°

Notes:I. For 3° < a < 5° coefficients may be reduced 10% for comer coefficients, C, only.2. For 0° < a < 3°, use Figure 1606.2D.

10 20 50 100200 500 1000EFFECTIVE WIND AREA (sq. ft.)

-3.6-3.4

-3.2=~8-3.0~2.8

-2.6

-2.0-1.8

GC -1.6 t( rP -1.4

-1.2-1.0

-0.8-0.6-0.4-0.2o

ROOF:

r::sJI. B .1

FIGURE 1606.2GMONOSLOPE ROOF COEFFICIENTS, GCp, COMPONENTS AND CLADDING

10° < a ~ 30°


1607 -1607.1.6

SECTION 1607EARTHQUAKE LOADS

1607.1 General1607.1.1 Scope. Every building and structure, and portionthereof, shall be designed and constructed to resist theeffects of earthquake motions determined in accordancewith 1607. Additions and change of occupancy to existingbuildings and structures shall be designed and constructedto resist the effects of earthquake motions determined inaccordance with 1607. Special structures, including butnot limited to vehicular bridges, transmission towers,industrial towers and equipment, piers and wharves, andhydraulic structures shall be designed for earthquakeloads using a properly substantiated analysis. As an alternate, buildings, structures, and special structures, asdescribed in Section 9.2.6 ofASCE 7, shall be designed toresist the effects of earthquake motions determined inaccordance with Section 9, Earthquake Loads, of ASCE 7.

Exceptions:1. Buildings of detached one and two family

dwellings (Group R3) that are located in seismicmap areas having an effective peak velocityrelated acceleration value, A v' according to1607.1.5, less than 0.15 are exempt from therequirements of 1607.

2. Agricultural storage buildings which are intended only for incidental human occupancy areexempt from the requirements of 160i

3. Buildings or structures located where the seismiccoefficient representing the effective peak velocity-related acceleration, A v' is less than 0.05 needonly comply with 1607.3.6.1.

4. Buildings of detached one and two-familydwellings (Group R3) with a building height notmore than 35 feet (l0.7 m) or two stories, whichhave seismic load-resisting systems which areentirely of wood frame construction in accordance with the requirements of Chapter 23, andare located in seismic map areas having an effective peak velocity-related acceleration, Av' equalto or greater than 0.15, need only comply with1607.3.6.1.

5. Buildings assigned to Seismic PerformanceCategory B, according to 1607.1.5 and 1607.1.8,which have seismic load-resisting systems whichare entirely of light frame wood construction inaccordance with the provisions of Chapter 23,need only comply with 1607.3.6.1.

1607.1.2 Required design data. Where earthquake loadsare applicable, the following design data shall be indicated on the design drawings:

1. The peak velocity related acceleration, A v' according to 1607.1.5.

2. The peak acceleration, Aa, according to 1607.1.5.3.The Seismic Hazard Exposure Group according to1607.1.6.

228

4. The Seismic Performance Category according to1607.1.8.

5. The soil profile type according to Table 1607.3.1.6. The basic structural system and seismic resisting

system according to Table 1607.3.3.7. The response modification factor, R, and the deflecc

tion amplification factor, Cd' according to Table1607.3.3.

8. The analysis procedure utilized in accordance with1607.4 or 1607.5 as applicable.

1607.1.3 Additions to existing buildings. An additionwhich is structurally independent from an existing building shall be designed and constructed in accordance withthe seismic requirements for new buildings. An additionwhich is not structurally independent from an existingbuilding shall be designed and constructed such that theentire building conforms to the seismic requirements fornew buildings unless the following three provisions arecomplied with:

1. The addition complies with the seismic requirements for new buildings,

2. The addition shall not increase the seismic forces inany structural element of the existing building bymore than 5% unless the increased forces on the element are still in compliance with these provisions.

3. The addition shall not decrease the seismic resistance of any structural element of the existing building below that required for new buildings.

1607.1.4 Change of occupancy. When a change of occupancy results in an existing building being reclassified toa higher Seismic Hazard Exposure Group, the buildingshall conform to the seismic requirements for new buildings.

Exception: Upgrading the building for the seismicrequirements of this section is not required for buildings located in seismic map areas having an effectivepeak velocity-related acceleration, A v' value of lessthan 0.15 when the change of use results in a buildingbeing reclassified from Seismic Hazard ExposureGroup I to Seismic Hazard Exposure Group II.

1607.1.5 Seismic ground acceleration maps. The effective peak velocity-related acceleration, A v' and the effective peak acceleration, Aa, shall be determined fromFigures 1607.1.5A and 1607.1.5B, respectively.Interpolation shall be permitted in the determination of theeffective peak velocity-related acceleration, A v' and theeffective peak acceleration, A a. Where site-specificground motions are used or required, they shall be developed with 90% probability of ground motion not beingexceeded in 50 years.

1607.1.6 Seismic hazard exposure groups. All buildingsshall be assigned to one of the following Seismic HazardExposure Groups in Table 1607.1.6.


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sbc chp 15 wind loading

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