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SECTION 1607 LIVE LOADS
1607.1 General. Live
loads are those loads defined in Section
1602.1.
1607.2 Loads not specified.
For occupancies or uses not designated in Table
1607.1, the live load shall be determined in accordance
with a method approved by the building official.
1607.3
Uniform live loads. The live loads
used in the design of buildings and other structures shall
be the maximum loads expected by the intended use or occupancy
but shall in no case be less than the minimum uniformly distributed
unit loads required by Table 1607.1.
1607.4
Concentrated loads. Floors and other
similar surfaces shall be designed to support the uniformly
distributed live loads prescribed in Section 1607.3 or the
concentrated load, in pounds (kilonewtons), given in Table
1607.1, whichever produces the greater load effects. Unless
otherwise specified, the indicated concentration shall be
assumed to be uniformly distributed over an area 2.5 feet
by 2.5 feet [6.25 square feet (0.58 m2)] and shall
be located so as to produce the maximum load effects in the
structural members.
1607.5
Partition loads. In office buildings
and in other buildings where partition locations are subject
to change, provisions for partition weight shall be made,
whether or not partitions are shown on the construction documents,
unless the specified live load exceeds 80 psf (3.83 kN/m2).
The partition load shall not be less than a uniformly distributed
live load of 15 psf (0.74 kN/m2).
1607.6
Truck and bus garages. Minimum live
loads for garages having trucks or buses shall be as specified
in Table 1607.6, but shall
not be less than 50 psf (2.40 kN/m2), unless other
loads are specifically justified and approved by the building
official. Actual loads shall be used where they are greater
than the loads specified in the table.
1607.6.1
Truck and bus garage live load application. The concentrated
load and uniform load shall be uniformly distributed over
a 10- foot (3048 mm) width on a line normal to the centerline
of the lane placed within a 12-foot-wide (3658 mm) lane.
The loads shall be placed within their individual lanes
so as to produce the maximum stress in each structural member.
Single spans shall be designed for the uniform load in Table
1607.6 and one simultaneous concentrated load positioned
to produce the maximum effect. Multiple spans shall be designed
for the uniform load in Table
1607.6 on the spans and two simultaneous concentrated
loads in two spans positioned to produce the maximum negative
moment effect. Multiple span design loads, for other effects,
shall be the same as for single spans.
1607.7
Loads on handrails, guards, grab bars and vehicle barriers.
Handrails, guards, grab bars as designed in ICC A117.1 and
vehicle barriers shall be designed and constructed to the
structural loading conditions set forth in this section.
1607.7.1
Handrails and guards. Handrail assemblies and guards
shall be designed to resist a load of 50 plf (0.73 kN/m)
applied in any direction at the top and to transfer this
load through the supports to the structure. Glass handrail
assemblies and guards shall also comply with Section
2407.
Exceptions:
1.
For one- and two-family dwellings, only the single concentrated
load required by Section 1607.7.1.1 shall be applied.
2.
In Group 1-3, F, Hand S occupancies, for areas that are
not accessible to the general public and that have an occupant
load less than 50, the minimum load shall be 20 pounds per
foot (0.29 kN/m) .
1607.7.1.1 Concentrated load. Handrail assemblies
and guards shall be able to resist a single concentrated
load of 200 pounds (0.89 kN), applied in any direction
at any point along the top, and have attachment devices
and supporting structure to transfer this loading to appropriate
structural elements of the building. This load need not
be assumed to act concurrently with the loads specified
in the preceding paragraph.
1607.7.1.2
Components. Intermediate rails (all those except the
handrail), balusters and panel fillers shall be designed
to withstand a horizontally applied normal load of 50
pounds (0.22 kN) on an area equal to 1 square foot (0.093m2),
including openings and space between rails. Reactions
due to this loading are not required to be superimposed
with those of Section 1607.7.1 or 1607.7.1.1.
1607.7.1.3
Stress increase. Where handrails and guards are designed
in accordance with the provisions for allowable stress
design (working stress design) exclusively for the loads
specified in Section 1607.7.1, the allowable stress for
the members and their attachments are permitted to be
increased by one-third.
1607.7.2
Grab bars, shower seats and dressing room bench seats.
Grab bars, shower seats and dressing room bench seat systems
shall be designed to resist a single concentrated load of
250 pounds (1.11 kN) applied in any direction at any point.
1607.7.3 Vehicle barriers.
Vehicle barrier systems for passenger cars shall be designed
to resist a single load of 6,000 pounds (26.70 kN) applied
horizontally in any direction to the barrier system and
shall have anchorage or attachment capable of transmitting
this load to the structure. For design of the system, the
load shall be assumed to act at a minimum height of 1 foot,
6 inches (457 mm) above the floor or ramp surface on an
area not to exceed 1 square foot (305 mm2), and
is not required to be assumed to act concurrently with any
handball or guard loadings specified in the preceding paragraphs
of Section 1607.7.1. Garages accommodating trucks and buses
shall be designed in accordance with an approved method
that contains provision for traffic railings.
1607.8 Impact loads.
The live loads specified in Section 1607.3 include allowance
for impact conditions. Provisions shall be made in the structural
design for uses and loads that involve unusual vibration and
impact forces.
1607.8.1
Elevators. Elevator loads shall be increased by 100
percent for impact and the structural supports shall be
designed within the limits of deflection prescribed by ASMEA17.1.
1607.8.2
Machinery. For the purpose of design, the weight of
machinery and moving loads shall be increased as follows
to allow for impact: (1) elevator machinery, 100 percent;
(2) light machinery, shaft- or motor-driven, 20 percent;
(3) reciprocating machinery or power-driven units, 50 percent;
(4) hangers for floors or balconies, 33 percent. Percentages
shall be increased where specified by the manufacturer.
1607.9
Reduction in live loads. Except
for roof uniform live loads, all other minimum uniformly distributed
live loads, LO, in Table
1607.1 are permitted to be reduced in accordance with
Section 1607.9.1 or 1607.9.2.
1607.9.1
General. Subject to the limitations of Sections 1607.9.1.1
through 1607.9.1.4, members for which a value of KLLAT
is 400 square feet (37.16 m2) or more are permitted
to be designed for a reduced live load in accordance with
the following equation:
(Equation 16-24)
where:
L
= Reduced design live load per square foot (meter) of area
supported by the member.
La
= Unreduced design live load per square foot (meter) of
area supported by the member (see Table
1607.1).
KLL= Live load element
factor (see Table 1607.9.1).
AT
= Tributary area, in square feet (square meters). L shall
not be less than 0.50Lo for members supporting
one floor and L shall not be less than 0.40Lo
for members supporting two or more floors.
1607.9.1.1 Heavy live loads. Live loads that exceed
100 psf (4.79 kN/m2) shall not be reduced.
Exceptions:
1. The
live loads for members supporting two or more floors
are permitted to be reduced by a maximum of 20 percent,
but the live load shall not be less than L as calculated
in Section 1607.9.1.
2. For
uses other than storage, where approved, additional
live load reductions shall be permitted where shown
by the registered design professional that a rational
approach has been used and that such reductions are
warranted.
1607.9.1.2
Passenger vehicle garages. The live loads shall not
be reduced in passenger vehicle garages except the live
loads for members supporting two or more floors are permitted
to be reduced by a maximum of 20 percent, but the live
load shall not be less than L as calculated in Section
1607.9.1.
1607.9.1.3 Special occupancies. Live loads of 100
psf (4.79 kN/m2) or less shall not be reduced
in public assembly occupancies.
1607.9.1.4 Special structural elements. Live loads
shall not be reduced for one-way slabs except as permitted
in Section 1607.9.1.1. Live loads of 100 psf (4.79 kN/m2)
or less shall not be reduced for roof members except as
specified in Section 1607.11.2.
1607.9.2
Alternate floor live load reduction. As an alternative
to Section 1607.9.1, floor live loads are permitted to be
reduced in accordance with the following provisions. Such
reductions shall apply to slab systems, beams, girders,
columns, piers, walls and foundations.
1. A
reduction shall not be permitted in Group A occupancies.
2. A
reduction shall not be permitted where the live load exceeds
100 psf (4.79 kN/m2) except that the design
live load for members supporting two or more floors is
permitted to be reduced by 20 percent.
3. A
reduction shall not be permitted in passenger vehicle
parking garages except that the live loads for members
supporting two or more floors are permitted to be reduced
by a maximum of 20 percent.
4. For
live loads not exceeding 100 psf (4.79 kN/m2),
the design live load for any structural member supporting
150 square feet (13.94 m2) or more is permitted
to be reduced in accordance with the following equation:
R = 0.08 (A -150)
(Equation 16-25)
For SI: R =
0.861 (A -13.94)
Such reduction shall not
exceed the smallest of:
1. 40 percent
for horizontal members;
2. 60 percent
for vertical members; or
3. R as determined
by the following equation.
R = 23.1 (1 + D/Lo)
(Equation 16-26)
where:
A = Area of
floor supported by the member, square feet (m2),
D = Dead load per
square foot (m2) of area supported.
La =
Unreduced live load per square foot (m2)
of area supported.
R =
Reduction in percent.
1607.10 Distribution of floor loads.
Where uniform floor live loads are involved in the design
of structural members arranged so as to create continuity,
the minimum applied loads shall be the full dead loads on
all spans in combination with the floor live loads on spans
selected to produce the greatest effect at each location under
consideration. It shall be permitted to reduce floor live
loads in accordance with Section 1607.9.
1607.11
Roof loads. The structural supports
of roofs and marquees shall be designed to resist wind and,
where applicable, snow and earthquake loads, in addition to
the dead load of construction and the appropriate live loads
as prescribed in this section, or as set forth in Table
1607.1. The live loads acting on a sloping surface shall
be assumed to act vertically on the horizontal projection
of that surface.
1607.11.1
Distribution of roof loads. Where uniform roof live
loads are reduced to less than 20 psf (0.96 kN/m2)
in accordance with Section 1607.11.2.1 and are involved
in the design of structural members arranged so as to create
continuity, the minimum applied loads shall be the full
dead loads on all spans in combination with the roof live
loads on adjacent spans or on alternate spans, whichever
produces the greatest effect. See Section 1607.11.2 for
minimum roof live loads and Section 7.5
of ASCE 7 for partial snow loading.
1607.11.2
Reduction in roof live loads. The minimum uniformly
distributed roof live loads, Lo in Table
1607.1 are permitted to be reduced according to the
following provisions.
1607.11.2.1
Flat, pitched and curved roofs. Ordinary flat, pitched
and curved roofs are permitted to be designed for a reduced
roof live load as specified in the following equation
or other controlling combinations of loads in Section
1605, whichever produces the greater load. In structures
where special scaffolding is used as a work surface for
workers and materials during maintenance and repair operations,
a lower roof load than specified in the following equation
shall not be used unless approved by the building official.
Greenhouses shall be designed for a minimum roof live
load of 12 psf (0.58 kN/m2).
Lr = LoR1R2
(Equation 16-27)
where: 12 ≤
Lr ≤ 20
For SI: Lr
= Lo R1R2
where: 0.58 ≤
Lr ≤ 0.96
Lr = Reduced
live load per square foot (m2) of horizontal
projection in pounds per square foot (kN/m2).
The reduction factors R1 and R2 shall be
determined as follows:
R1 =
1 for At ≤ 200 square feet (18.58m2)
(Equation 16-28)
R1 =
1.2 – 0.001At for 200 square feet <At
< 600 square feet (Equation 16-29)
For SI: 1.2 – 0.011At
for 18.58 square meters < At < 55.74
square meters
R1 = 0.6 for At >
600 square feet (55.74m2)
(Equation 16-30)
where:
At
= Tributary area (span length multiplied by effective
width) in square feet (m2) supported by
any structural
member, and
R2
= 1 for F≤ 4 (Equation 16-31)
R2
= 1.2 – 0.05 F for 4 < F< 12 (Equation
16-32)
R2
= 0.6 for F > 12 (Equation 16-33)
where:
F
= For a sloped roof, the number of inches of
rise per foot (for SI: F = 0.12 × slope, with slope
expressed as a percentage), or for an arch or dome,
the rise-to-span ratio multiplied by 32.
1607.11.2.2 Special-purpose roofs. Roofs used for
promenade purposes, roof gardens, assembly purposes or
other special purposes shall be designed for a minimum
live load as required in Table
1607.1. Such roof live loads are permitted to be reduced
in accordance with 1607.9.
1607.11.2.3 Landscaped roofs. Where roofs are to
be landscaped, the uniform design live load in the landscaped
area shall be 20 psf (0.958 kN/m2). The weight
of the landscaping materials shall be considered as dead
load and shall be computed on the basis of saturation
of the soil.
1607.11.2.4 Awnings and canopies. Awnings and canopies
shall be designed for uniform live loads as required in
Table 1607.1 as well as
for snow loads and wind loads as specified in Sections
1608 and 1609.
1607.12
Crane loads. The crane live load
shall be the rated capacity of the crane. Design loads for
the runway beams, including connections and support brackets,
of moving bridge cranes and monorail cranes shall include
the maximum wheel loads of the crane and the vertical impact,
lateral and longitudinal forces induced by the moving crane.
1607.12.1
Maximum wheel load. The maximum wheel loads shall be
the wheel loads produced by the weight of the bridge, as
applicable, plus the sum of the rated capacity and the weight
of the trolley with the trolley positioned on its runway
at the location where the resulting load effect is maximum.
1607.12.2
Vertical impact force. The maximum wheel loads of the
crane shall be increased by the percentages shown below
to determine the induced vertical impact or vibration force:
Monorail
cranes (powered) · · · · · · · · · 25 percent
Cab-operated or remotely operated
bridge cranes (powered) · · · · · · · · · · · 25 percent
Pendant-operated bridge cranes (powered) · 10 percent
Bridge cranes or monorail cranes with
hand-geared bridge, trolley and hoist · · · · · 0 percent
1607.12.3 Lateral force.
The lateral force on crane runway beams with electrically
powered trolleys shall be calculated as 20 percent of the
sum of the rated capacity of the crane and the weight of
the hoist and trolley. The lateral force shall be assumed
to act horizontally at the traction surface of a runway
beam, in either direction perpendicular to the beam, and
shall be distributed according to the lateral stiffness
of the runway beam and supporting structure.
1607.12.4
Longitudinal force. The longitudinal force on crane
runway beams, except for bridge cranes with hand-geared
bridges, shall be calculated as 10 percent of the maximum
wheel loads of the crane. The longitudinal force shall be
assumed to act horizontally at the traction surface of a
runway beam, in either direction parallel to the beam.
1607.13 Interior walls and partitions.
Interior walls and partitions that exceed 6 feet (1829 mm)
in height, including their finish materials, shall have adequate
strength to resist the loads to which they are subjected but
not less than a horizontal load of 5 psf (0.240 kN/m2).
Exception:
Fabric partitions complying with Section 1607.13.1 shall not
be required to resist the minimum horizontal load of 5 psf
(0.24 kN/m2).
1607.13.1
Fabric partitions. Fabric partitions that exceed 6 feet
(1829 mm) in height, including their finish materials, shall
have adequate strength to resist the following load conditions:
I.
A horizontal distributed load of 5 psf (0.24 kN/m2)
applied to the partition framing. The total area used
to determine the distributed load shall be the area of
the fabric face between the framing members to which the
fabric is attached. The total distributed load shall be
uniformly applied to such framing members in proportion
to the length of each member.
2.
A concentrated load of 40 pounds (0.176 kN) applied to
an 8-inch diameter (203 mm) area [50.3 square inches (32
452 mm2)] of the fabric face at a height of
54 inches (1372 mm) above the floor.
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