ALLOWABLE STRESS DESIGN.
A method of proportioning structural members, such that
elastically computed stresses produced in the members by
nominal loads do not exceed specified allowable stresses
(also called “working stress design”).
BALCONY, EXTERIOR. An
exterior floor projecting from and supported by a structure
without additional independent supports.
DEAD LOADS. The weight
of materials of construction incorporated into the building,
including but not limited to walls, floors, roofs, ceilings,
stairways, builtin partitions, finishes, cladding and other
similarly incorporated architectural and structural items,
and the weight of fixed service equipment, such as cranes,
plumbing stacks and risers, electrical feeders, heating,
ventilating and air-conditioning systems and fire sprinkler
systems.
DECK. An exterior floor
supported on at least two opposing sides by an adjacent
structure, and/or posts, piers or other independent supports.
DESIGN STRENGTH. The
product of the nominal strength and a resistance factor
(or strength reduction factor).
DIAPHRAGM. A horizontal
or sloped system acting to transmit lateral forces to the
vertical-resisting elements. When the term “diaphragm”
is used, it shall include horizontal bracing systems. Diaphragm,
blocked. In light-frame construction, a diaphragm in which
all sheathing edges not occurring on a framing member are
supported on and fastened to blocking. Diaphragm boundary.
In light-frame construction, a location where shear is transferred
into or out of the diaphragm sheathing. Transfer is either
to a boundary element or to another force-resisting element.
Diaphragm chord. A diaphragm boundary element perpendicular
to the applied load that is assumed to take axial stresses
due to the diaphragm moment. Diaphragm flexible. A diaphragm
is flexible for the purpose of distribution of story shear
and torsional moment where so indicated in
Section 12.3.1 ofASCE7, as modified in
Section 1613.6.1. Diaphragm, rigid. A diaphragm is rigid
for the purpose of distribution of story shear and torsional
moment when the lateral deformation of the diaphragm is
less than or equal to two times the average story drift.
DURATION OF LOAD. The
period of continuous application of a given load, or the
aggregate of periods of intermittent applications of the
same load.
ESSENTIAL FACILITIES.
Buildings and other structures that are intended to remain
operational in the event of extreme environmental loading
from flood, wind, snow or earthquakes.
FABRIC PARTITIONS. A
partition consisting of a finished surface made of fabric,
without a continuous rigid backing, that is directly attached
to a framing system in which the vertical framing members
are spaced greater than 4 feet (1219 mm) on center.
FACTORED LOAD. The product
of a nominal load and a load factor. GUARD. See
Section 1002.1.
IMPACT LOAD. The load
resulting from moving machinery, elevators, crane ways,
vehicles and other similar forces and kinetic loads, pressure
and possible surcharge from fixed or moving loads.
LIMIT STATE. A condition
beyond which a structure or member becomes unfit for service
and is judged to be no longer useful for its intended function
(serviceability limit state) or to be unsafe (strength limit
state).
LIVE LOADS. Those loads
produced by the use and occupancy of the building or other
structure and do not include construction or environmental
loads such as wind load, snow load, rain load, earthquake
load, flood load or dead load.
LIVE LOADS (ROOF). Those
loads produced (1) during maintenance by workers, equipment
and materials; and (2) during the life of the structure
by movable objects such as planters and by people.
LOAD AND RESISTANCE FACTOR
DESIGN (LRFD). A method of proportioning structural
members and their connections using load and resistance
factors such that no applicable limit state is reached when
the structure is subjected to appropriate load combinations.
The term “LRFD” is used in the design of steel
and wood structures.
LOAD EFFECTS. Forces
and deformations produced in structural members by the applied
loads.
LOAD FACTOR. A factor
that accounts for deviations of the actual load from the
nominal load, for uncertainties in the analysis that transforms
the load into a load effect, and for the probability that
more than one extreme load will occur simultaneously.
LOADS. Forces or other
actions that result from the weight of building materials,
occupants and their possessions, environmental effects,
differential movement and restrained dimensional changes.
Permanent loads are those loads in which variations over
time are rare or of small magnitude, such as dead loads.
All other loads are variable loads (see also “Nominal
loads”).
NOMINAL LOADS. The magnitudes
of the loads specified in this chapter (dead, live, soil,
wind, snow, rain, flood and earthquake). OCCUPANCY CATEGORY.
A category used to determine structural requirements based
on occupancy. OTHER STRUCTURES. Structures, other than buildings,
for which loads are specified in this chapter.
PANEL (PART OF A STRUCTURE).
The section of a floor, wall or roof comprised between
the supporting frame of two adjacent rows of columns and
girders or column bands of floor or roof construction.
RESISTANCE FACTOR. A
factor that accounts for deviations of the actual strength
from the nominal strength and the manner and consequences
of failure (also called “strength reduction factor”).
STRENGTH, NOMINAL. The
capacity of a structure or member to resist the effects
of loads, as determined by computations using specified
material strengths and dimensions and equations derived
from accepted principles of structural mechanics or by field
tests or laboratory tests of scaled models, allowing for
modeling effects and differences between laboratory and
field conditions.
STRENGTH, REQUIRED.
Strength of a member, cross section or connection required
to resist factored loads or related internal moments and
forces in such combinations as stipulated by these provisions.
STRENGTH DESIGN. A method
of proportioning structural members such that the computed
forces produced in the members by factored loads do not
exceed the member design strength [also called “load
and resistance factor design” (LRFD)]. The term “strength
design” is used in the design of concrete and masonry
structural elements.
VEHICLE BARRIER SYSTEM.
A system of building components near open sides of a garage
floor or ramp or building walls that act as restraints for
vehicles.
NOTATIONS.
D = Dead load.
E = Combined effect of horizontal
and vertical earthquake induced forces as defined in Section
12.4.2 of ASCE 7.
Em = Maximum seismic
load effect of horizontal and vertical seismic forces
as set forth in Section 12.4.3
of ASCE 7.
F = Load due to fluids with
well-defined pressures and maximum heights.
Fa = Flood load.
H = Load due to lateral earth
pressures, ground water pressure or pressure of bulk materials.
L = Live load, except roof
live load, including any permitted live load reduction.
Lr = Roof live
load including any permitted live load reduction.
R = Rain load.
S = Snow load.
T = Self-straining force
arising from contraction or expansion resulting from temperature
change, shrinkage, moisture change, creep in component
materials, movement due to differential settlement or
combinations thereof.
W = Load due to wind pressure.
