Buildings, structures and parts thereof shall be designed to
withstand the minimum wind loads prescribed herein. Decreases in wind loads
shall not be made for the effect of shielding by other structures.
1609.1.1
Determination of wind
loads. Wind loads on every building or structure shall be determined in
accordance with Chapter 6 of ASCE 7 or provisions of the alternate all-heights
method in Section 1609.6. The type of opening protection required, the basic
wind speed and the exposure category for a site is permitted to be determined
in accordance with Section 1609 or ASCE 7. Wind shall be assumed to come from
any horizontal direction and wind pressures shall be assumed to act normal to
the surface considered.
Exceptions:
1. Subject to the limitations of Section
1609.1.1.1, the provisions of ICC 600 shall be permitted for applicable Group
R-2 and R-3 buildings.
2. Subject
to the limitations of Section 1609.1.1.1, residential structures using the
provisions of the AF & PA WFCM.
3. Subject to the limitations of Section
1609.1.1.1, residential structures using the provisions of AISI S230.
4. Designs using NAAMM FP 1001.
5. Designs using TIA-222 for
antenna-supporting structures and antennas.
6. Wind tunnel tests in accordance with
Section 6.6 of ASCE 7, subject to the limitations in Section
1609.1.1.2.
1609.1.1.1
Applicability. The provisions of ICC 600 are applicable only to
buildings located within Exposure B or C as defined in Section 1609.4. The
provisions of ICC 600, AF & PA WFCM and AISI S230 shall not apply to
buildings sited on the upper half of an isolated hill, ridge or escarpment
meeting the following conditions:
1. The hill,
ridge or escarpment is 60 feet (18 288 mm) or higher if located in Exposure B
or 30 feet (9144 mm) or higher if located in Exposure C;
2. The maximum average slope of the hill
exceeds 10 percent; and
3. The
hill, ridge or escarpment is unobstructed upwind by other such topographic
features for a distance from the high point of 50 times the height of the hill
or 1 mile (1.61 km), whichever is greater.
1609.1.1.2
Wind tunnel test
limitations. The lower limit on pressures for main wind-force-resisting
systems and components and cladding shall be in accordance with Sections
1609.1.1.2.1 and 1609.1.1.2.2.
1609.1.1.2.1
Lower limits on main wind-force-resisting system. Base
overturning moments determined from wind tunnel testing shall be limited to not
less than 80 percent of the design base overturning moments determined in
accordance with Section 6.5 of ASCE 7, unless specific testing is performed
that demonstrates it is the aerodynamic coefficient of the building, rather
than shielding from other structures, that is responsible for the lower values.
The 80-percent limit shall be permitted to be adjusted by the ratio of the
frame load at critical wind directions as determined from wind tunnel testing
without specific adjacent buildings, but including appropriate upwind
roughness, to that determined in Section 6.5 of ASCE 7.
1609.1.1.2.2
Lower limits on components
and cladding. The design pressures for components and cladding on walls
or roofs shall be selected as the greater of the wind tunnel test results or 80
percent of the pressure obtained for Zone 4 for walls and Zone 1 for roofs as
determined in Section 6.5 of ASCE 7, unless specific testing is performed that
demonstrates it is the aerodynamic coefficient of the building, rather than
shielding from nearby structures, that is responsible for the lower values.
Alternatively, limited tests at a few wind directions without specific adjacent
buildings, but in the presence of an appropriate upwind roughness, shall be
permitted to be used to demonstrate that the lower pressures are due to the
shape of the building and not to shielding.
1609.1.2
Protection of
openings. In wind-borne debris regions, glazing in
buildings shall be impact resistant or protected with an impact-resistant
covering meeting the requirements of an approved
impact-resistant standard or ASTM E 1996 and ASTM E 1886 referenced herein as
follows:
1. Glazed openings located within 30
feet (9144 mm) of grade shall meet the requirements of the large missile test
of ASTM E 1996.
2. Glazed openings
located more than 30 feet (9144 mm) above grade shall meet the provisions of
the small missile test of ASTM E 1996.
Exceptions:
1. Wood structural panels with a minimum
thickness of 7/16 inch (11.1
mm) and maximum panel span of 8 feet (2438 mm) shall be permitted for opening
protection in one- and two-story buildings classified as Group R-3 or R-4
occupancy. Panels shall be precut so that they shall be attached to the framing
surrounding the opening containing the product with the glazed opening. Panels
shall be predrilled as required for the anchorage method and shall be secured
with the attachment hardware provided. Attachments shall be designed to resist
the components and cladding loads determined in accordance with the provisions
of ASCE 7, with corrosion-resistant attachment hardware provided and anchors
permanently installed on the building. Attachment in accordance with Table
1609.1.2 with corrosion-resistant attachment hardware provided and anchors
permanently installed on the building is permitted for buildings with a mean
roof height of 45 feet (13 716 mm) or less where wind speeds do not exceed 140
mph (63 m/s).
2. Glazing in
Occupancy Category I buildings as defined in Section 1604.5,
including greenhouses that are occupied for growing plants on a production or
research basis, without public access shall be permitted to be
unprotected.
3. Glazing in
Occupancy Category II, III or IV buildings located over 60
feet (18 288 mm) above the ground and over 30 feet (9144 mm) above aggregate
surface roofs located within 1,500 feet (458 m) of the building shall be
permitted to be unprotected.
TABLE 1609.1.2 WIND-BORNE DEBRIS PROTECTION FASTENING
SCHEDULE FOR WOOD STRUCTURAL PANELSa, b, c,
d
|
FASTENER
TYPE |
FASTENER SPACING
(inches) |
|
Panel Span
<= 4 feet |
4 feet < Panel Span <= 6 feet |
6 feet < Panel Span <= 8 feet |
| No. 8 wood-screw-based anchor with 2-inch embedment
length |
16 |
10 |
8 |
| No. 10 wood-screw-based anchor with 2-inch embedment
length |
16 |
12 |
9 |
1/4-inch diameter
lag-screw-based anchor with 2-inch embedment length |
16 |
16 |
16 |
|
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1
pound = 4.448 N, 1 mile per hour = 0.447 m/s.
a. This table is based on 140 mph wind speeds and
a 45-foot mean roof height.
b.Fasteners shall be installed at opposing ends of
the wood structural panel. Fasteners shall be located a minimum of 1 inch from
the edge of the panel.
c. Anchors shall penetrate through the exterior
wall covering with an embedment length of 2 inches minimum into the building
frame. Fasteners shall be located a minimum of
21/2 inches from the edge of
concrete block or concrete.
d. Where panels are attached to masonry or
masonry/stucco, they shall be attached using vibration-resistant anchors having
a minimum ultimate withdrawal capacity of 1,500 pounds. |
1609.1.2.1
Louvers. Louvers
protecting intake and exhaust ventilation ducts not assumed to be open that are
located within 30 feet (9144 mm) of grade shall meet requirements of an
approved impact-resisting standard or the large missile test
of ASTM E 1996.
1609.1.2.2
Garage doors. Garage door glazed opening protection for wind-borne
debris shall meet the requirements of an approved
impact-resisting standard or ANSI/DASMA 115.
