Code of Massachusetts Regulations › 780 CMR - STATE BOARD OF BUILDING REGULATIONS AND STANDARDS › Chapter 16 - Structural Design › Section 1602 - DEFINITIONS AND NOTATIONS › Subsection 1602.1 - Definitions

Current through Register 1525, July 5, 2024
The following words and terms shall, for the purposes of
				  this chapter, have the meanings shown herein.
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").
DEAD LOADS.
The weight of materials of
				  construction incorporated into the building, including but not limited to
				  walls, floors, roofs, ceilings, stairways, built-in 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 automatic sprinkler systems.
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 of ASCE 7, 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 PARTITION.
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.
F
=
Load due to fluids with well-defined pressures and
							 maximum heights.
F
a
=
Flood load in accordance with Chapter 5 of ASCE
							 7.
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.
L
r
=
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.