The provisions of Section 1613.6 shall be permitted as
alternatives to the relevant provisions of ASCE 7.
1613.6.1
Assumption of flexible
diaphragm. Add the following text at the end of Section 12.3.1.1 of ASCE
7.
Diaphragms constructed of wood structural panels or untopped
steel decking shall also be permitted to be idealized as flexible, provided all
of the following conditions are met:
1. Toppings of concrete or similar materials
are not placed over wood structural panel diaphragms except for nonstructural
toppings no greater than 11/2
inches (38 mm) thick.
2. Each line
of vertical elements of the seismic-force-resisting system complies with the
allowable story drift of Table 12.12-1.
3. Vertical elements of the
seismic-force-resisting system are light-frame walls sheathed with wood
structural panels rated for shear resistance or steel sheets.
4. Portions of wood structural panel
diaphragms that cantilever beyond the vertical elements of the
lateral-force-resisting system are designed in accordance with Section 4.2.5.2
of AF & PA SDPWS.
1613.6.2
Additional
seismic-force-resisting systems for seismically isolated structures. Add
the following exception to the end of Section 17.5.4.2 of ASCE 7:
Exception: For isolated structures designed in
accordance with this standard, the Structural System Limitations and the
Building Height Limitations in Table 12.2-1 for ordinary steel concentrically
braced frames (OCBFs) as defined in Chapter 11 and ordinary moment frames
(OMFs) as defined in Chapter 11 are permitted to be taken as 160 feet (48 768
mm) for structures assigned to Seismic Design Category D, E or
F, provided that the following conditions are satisfied:
1. The value of
RI as defined in Chapter 17 is taken as
1.
2. For OMFs and OCBFs, design is
in accordance with AISC 341.
1613.6.3
Automatic sprinkler
systems.
Automatic sprinkler systems designed and
installed in accordance with NFPA 13 shall be deemed to meet the requirements
of Section 13.6.8 of ASCE 7.
1613.6.4
Autoclaved aerated concrete
(AAC) masonry shear wall design coefficients and system limitations. Add
the following text at the end of Section 12.2.1 of ASCE 7:
For ordinary reinforced AAC masonry shear walls used in the
seismic-force-resisting system of structures, the response modification factor,
R, shall be permitted to be taken as 2, the deflection
amplification factor, Cd, shall be
permitted to be taken as 2 and the system overstrength factor,
[OMEGA]o, shall be permitted to be taken as
21/2. Ordinary reinforced AAC
masonry shear walls shall not be limited in height for buildings assigned to
Seismic Design Category B, shall be limited in height to 35
feet (10 668 mm) for buildings assigned to Seismic Design
Category C and are not permitted for buildings assigned to
Seismic Design Categories D, E and F.
For ordinary plain (unreinforced) AAC masonry shear walls
used in the seismic-force-resisting system of structures, the response
modification factor, R, shall be permitted to be taken as
11/2, the deflection
amplification factor, Cd, shall be
permitted to be taken as 11/2
and the system overstrength factor,[OMEGA]o, shall be
permitted to be taken as
21/2. Ordinary plain
(unreinforced) AAC masonry shear walls shall not be limited in height for
buildings assigned to Seismic Design Category B and are not
permitted for buildings assigned to Seismic Design Categories
C, D, E and F.
1613.6.5
Seismic controls for elevators. Seismic switches in accordance
with Section 8.4.10 of ASME A17.1 shall be deemed to comply with Section
13.6.10.3 of ASCE 7.
1613.6.6
Steel plate shear wall height limits. Modify Section 12.2.5.4 of
ASCE 7 to read as follows
:
12.2.5.
4 Increased building height
limit for steel- braced frames, special steel plate shear walls and special
reinforced concrete shear walls. The height limits in Table 12.2-1 are
permitted to be increased from 160 feet (48 768 mm) to 240 feet (75 152 mm) for
structures assigned to
Seismic Design Category D or E and from
100 feet (30 480 mm) to 160 feet (48 768 mm) for structures assigned to
Seismic Design Category F that have steel-braced frames,
special steel plate shear walls or special reinforced concrete cast-in-place
shear walls and that meet both of the following requirements:
1. The structure shall not have an extreme
torsional irregularity as defined in Table 12.2-1 (horizontal structural
irregularity Type 1b).
2. The
braced frames or shear walls in any one plane shall resist no more than 60
percent of the total seismic forces in each direction, neglecting accidental
torsional effects.
1613.6.7
Minimum distance for building
separation. All buildings and structures shall be separated from
adjoining structures. Separations shall allow for the maximum inelastic
response displacement [DELTA]
M.
[DELTA]
M shall be determined at critical locations with
consideration for both translational and torsional displacements of the
structure using Equation 16-44.
|
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image |
(Equation 16-44) |
where:
Cd = Deflection
amplification factor in Table 12.2-1 of ASCE 7.
[DELTA]max = Maximum displacement
defined in Section 12.8.4.3 of ASCE 7.
I = Importance factor in accordance with
Section 11.5.1 of ASCE 7.
Adjacent buildings on the same property shall be separated by
a distance not less than [DELTA]MT, determined by
Equation 16-45.
|
Click to view
image |
(Equation 16-45) |
where:
[DELTA]M!,
[DELTA]M2 =The maximum inelastic response displacements
of the adjacent buildings in accordance with Equation 16-44.
Where a structure adjoins a property line not common to a
public way, the structure shall also be set back from the property line by not
less than the maximum inelastic response displacement,
[DELTA]M, of that structure.
Exceptions:
1. Smaller separations or property line
setbacks shall be permitted when justified by rational analyses.
2. Buildings and structures assigned to
Seismic Design Category A, B or C.
1613.6.8
HVAC ductwork with
Ip = 1.5. Seismic supports are
not required for HVAC ductwork with
Ip
= 1.5 if either of the following conditions is met for the full length of each
duct run:
1. HVAC ducts are suspended from
hangers 12 inches (305 mm) or less in length with hangers detailed to avoid
significant bending of the hangers and their attachments, or
2. HVAC ducts have a cross-sectional area of
less than 6 square feet (0.557 m2)..
