| AISC |
American Institute of Steel Construction |
| angle |
L-shaped section, common in bracing and
connections |
| arc weld |
welding process utilizing an electric arc to
melt base and filler metals |
| area load |
load applied over an area |
| area, cross-sectional |
area of member when cut perpendicular to its
longitudinal axis |
| ASD |
allowable stress design; factors of safety
are applied to the material strength |
| aspect ratio |
ratio of two perpendicular dimensions |
| axial |
action along length (long axis) of
member |
| axis |
straight line that a body rotates around, or
about which a body is symmetrical |
| base shear |
horizontal shear at base of structure due to
lateral wind or seismic forces |
| bay |
space between columns |
| beam |
horizontal member resisting forces through
bending |
| bearing |
compressive forces transmitted by two members
in direct contact |
| bearing wall |
wall that carries gravity loads |
| block shear |
connection failure mode characterized by
shear and tension failure |
| brace |
member resisting axial loads (typically
diagonal), supports other members |
| braced frame |
structural frame whose lateral resistance
comes from diagonal braces |
| brazing |
low temperature metal joining process |
| buckling |
excess deformation or collapse at loads below
the material strength |
| buckling restrained brace |
brace in concrete and steel jacket, with same
tension and compression capacity |
| camber |
intentional curvature in beams and trusses to
offset deflection |
| cantilever |
structural member projecting from a rigid
support on only one end |
| capacity |
ability to carry load, related to strength of
a member |
| carbon equivalence |
measure of steel weldability |
| channel |
C-shaped section, used as light beams |
| charpy test |
notch toughness test for quality control |
| chord |
truss or diaphragm element resisting tension
or compression forces |
| code |
compilation of rules governing the design of
buildings and other structures |
| collector |
see drag strut |
| column |
vertical member that primarily carries axial
compression load, supports floors and roofs |
| compact |
section capable of full yield prior to local
buckling |
| complete joint penetration |
groove weld through the entire joint
thickness |
| component |
single structural member or element |
| compression |
act of pushing together, shortening |
| connection |
region that joins two or more members
(elements) |
| construction documents |
written and graphical documents prepared to
describe the location, design, materials, and physical characteristics required to construct the
project |
| cope |
flange cutout to fit within receiving
member |
| core |
central building area, stacking vertically,
with stairs, elevators, and mechanical shafts, and heavy
structure |
| couple, or force couple |
parallel and equal, but opposite forces,
separated by a distance |
| creep |
slow, permanent material deformation under
sustained load |
| curtain wall |
glass and metal panel façade system |
| dead load |
weight of permanent materials |
| deflection δ |
movement of a member under load or settlement
of a support |
| demand |
internal force due to applied loads |
| depth |
height of bending member, or larger dimension
of column |
| design thickness |
assumed wall thickness to account for
manufacturing variations |
| detailing |
process of preparing detailed piece drawings
from engineering drawings |
| diaphragm |
floor or roof slab transmitting forces in its
plane to vertical lateral elements |
| discontinuity |
interruption in material |
| distributed load |
line load applied along the length of a
member |
| doubler |
plate added to a flange or web to increase
strength |
| drag strut |
element that collects diaphragm shear and
delivers it to a vertical lateral element |
| drift |
lateral displacement between adjacent floor
levels in a structure |
| durability |
ability to resist deterioration |
| eccentric braced frame |
braced frame with workpoints offset, causing
yielding in beam to dissipate energy |
| eccentricity |
offset of force from centerline of a member,
or centroid of a fastener group |
| edge distance |
distance between fastener center line and
edge of member |
| effective area |
net area adjusted to account for shear
lag |
| effective length |
length of member in compression, accounting
for end restraint |
| effective length factor |
factor to adjust member length, based on end
restraint conditions |
| elastic |
ability to return to original shape after
being loaded |
| element |
single structural member or part |
| empirical design |
design methodology based on rules of thumb or
past experience |
| end distance |
distance between fastener centerline and end
of member |
| erection drawings |
drawings showing each piece of steel, it’s
mark, and location in the structure |
| expansion joint |
separation between adjacent parts of the
structure, to allow relative movement and avoid cracking |
| expected strength |
actual material strength, usually above
specified strength |
| fatigue |
time-dependent crack growth due to cyclic
stresses |
| faying surfaces |
surfaces in contact in a connection |
| field weld |
weld that may or is required to be made in
the field |
| filler metal |
weld metal used to fill gaps or build up
welds |
| fillet weld |
weld made at the intersection between two
elements |
| fixed |
boundary condition that does not permit
translation or rotation |
| flare bevel weld |
weld made at the intersection between a
planar and curved surface |
| flexibility factors |
stiffness measurement in metal deck
diaphragms |
| flexure, flexural |
another word for bending behavior |
| footing |
foundation system bearing on soil near the
ground surface |
| force |
effect exerted on a body |
| forge welding |
welding process by folding and hammering
material causing it to overlap and mix |
| frame |
system of beams, columns, and braces,
designed to resist vertical and lateral loads |
| free body diagram |
elementary sketch showing forces acting on a
body |
| gage |
center-to-center spacing of fasteners |
| girder |
beam that supports other beams |
| gouge |
removal of material by mechanical means or
high temperature |
| gravity load |
weight of an object or structure, directed to
the center of the earth |
| grip |
thickness of material that a bolt joins |
| groove weld |
weld placed in a groove between connected
elements |
| gusset plate |
plate used to connect members, typically in
trusses or braced frames |
| high-strength bolt |
bolt with tensile strength above 100 k/in2
(690 MN/m2) |
| hollow structural section |
round or rectangular section, hollow in the
middle, common as braces and columns |
| HSS |
hollow structural section, rectangular or
round member |
| indeterminate |
problem that cannot be solved using the rules
of static equilibrium alone, number of unknowns greater than number
of static equilibrium equations |
| inelastic |
behavior that goes past yield, resulting in
permanent deformation |
| irregularity |
abrupt change in structure geometry causing
force concentrations |
| joint |
area where two or more members ends are
connected |
| lap joint |
joint made by overlapping two connection
elements |
| lateral bracing |
bracing intended to prevent buckling or
lateral torsional buckling |
| lateral load |
load applied in the horizontal direction,
perpendicular to the pull of gravity |
| lateral torsional buckling |
condition where beam rolls over near the
middle due to inadequate bracing for the given load |
| live load |
load from occupants or moveable building
contents |
| live load reduction |
code permitted reduction when area supported
by a single element is sufficiently large |
| load |
force applied to a structure |
| load combination |
expression combining loads that act
together |
| load factors |
factor applied to loads to account for load
uncertainty |
| load path |
route a load takes through a structure to
reach the ground |
| local buckling |
buckling of a portion of a member cross
section |
| LRFD |
load and resistance factor design, also
called strength design |
| modulus of elasticity E |
material stiffness parameter, measure of a
material’s tendency to deform when stressed |
| moment arm |
distance a force acts from a support
point |
| moment connection |
connection that transmits bending moments
between members |
| moment frame |
structural frame whose lateral resistance
comes from rigid beam-column joints |
| moment M |
twisting force, product of force and the
distance to a point of rotation |
| moment of inertia I |
geometric bending stiffness parameter,
property relating area and its distance from the neutral axis |
| net area |
area accounting for removal of material due
to holes or slots |
| neutral axis |
axis at which there is no lengthwise stress
or strain, point of maximum shear stress or strain, neutral axis
does not change length under load |
| nominal dimensions |
theoretical dimension, often used in tables
to identify members |
| nominal strength |
element strength, typically at ultimate
level, prior to safety factor application |
| nondestructive testing |
inspection procedure that leaves the part
undamaged, like ultrasonic testing |
| partial joint penetration |
groove weld through part of the joint
thickness |
| P-delta |
increased moment due to axial load and
deflection |
| pin |
boundary condition that allows rotation but
not translation |
| pitch |
lengthwise spacing of fasteners |
| plane strain |
condition where strain is zero in one
direction, perpendicular to applied stress, associated with thicker
material |
| plastic |
occurs after yield, where material
experiences permanent deformation after load is removed |
| plastic section modulus |
section property accounting for full section
yielding |
| plug weld |
weld made in a hole or slot |
| point load |
concentrated load applied at a discrete
location |
| point of inflection |
point in deflected shape where there is no
moment, deflected shape changes direction |
| pressure |
force per unit area |
| pretensioned bolt |
bolt tightened to a high percentage of its
tensile strength |
| protected zone |
member area where no connections are
permitted |
| prying |
increased tensile force in a bolt due to
plate bending |
| radius of gyration |
relationship between area and moment of
inertia used to predict buckling strength |
| reaction |
force resisting applied loads at end of
member or bottom of structure |
| rivets |
fastener created by hammering a hot, round
bar to form a head |
| roller |
boundary condition that allows rotation, but
limits translation in only one direction |
| row of fasteners |
fasteners in a line parallel to the applied
force |
| rupture |
complete separation of material |
| safety factor |
factor taking into account material strength
or load variability |
| section modulus |
geometric bending strength parameter |
| seismic design category |
classification based on occupancy and
earthquake severity |
| seismic load |
force accounting for the dynamic response of
a structure or element due to an earthquake |
| seismic response modification factor |
factor reducing seismic force based on energy
dissipation ability of the structure |
| seismic-force resisting system |
portion of structure designed to resist
earthquake effects |
| service load |
unfactored loads, used for checking
deflection |
| shear |
equal, but opposite forces or stresses,
acting to separate or cleave a material, like scissors |
| shear lag |
internal shear stress when connection is only
on part of a cross-section, creates non-uniform tensile stress in a
member |
| shear plate |
high-strength connection made from placing a
steel plate into a round groove, thereby engaging a large surface
area |
| shear wall |
wall providing lateral resistance for
structure |
| shop drawings |
drawings of each piece of steel, showing all
information required to fabricate it |
| sign convention |
method of assigning positive and negative
values to the direction of loads, reactions, and moments |
| simple connection |
connection that transmits negligible
moment |
| simplifying assumption |
assumption that makes the problem easier to
solve, but is realistic |
| slender |
member or element that is prone to
buckling |
| slip critical connection |
connection utilizing pretensioned bolts,
transferring force through friction |
| snow load |
load from fallen or drifted snow |
| snug tightened bolt |
bolt tightened with full effort of ironworker
on a spud wrench, keeping faying surfaces in contact |
| soft story |
story with substantially lower stiffness than
adjacent stories |
| spacing |
center-to-center distance between adjacent
items |
| span length |
clear distance between supports |
| special seismic systems |
structural systems specifically detailed to
absorb seismic energy through yielding |
| splice |
connection between ends of the same
element |
| stability |
structure’s resistance to excessive
deformation or collapse at loads below the material strength,
opposite of buckling |
| stiffener |
plate welded into structural member to
increase local strength |
| stiffness |
resistance to deformation when loaded |
| strain |
change in length divided by initial length,
percent change in length if multiplied by 100 |
| strength |
material or element resistance to load or
stress |
| strength design |
load and resistance factor design; safety
factors applied to the loads and materials |
| strength reduction factor |
LRFD material safety factor |
| structural analysis |
determination of forces, moments, shears,
torsion, reactions, and deformations due to applied loads |
| structural integrity |
ability of structure to redistribute forces
to maintain overall stability after localized damage occurs |
| structural system |
series of structural elements (beams,
columns, slabs, walls, footings) working together to resist
loads |
| support |
either the earth or another element that
resists movement of the loaded structure or element |
| sway frame |
flexible frame |
| tension |
act of pulling apart, lengthening |
| tension field action |
diagonal tension region due to shear forces,
and compression buckling |
| torsion |
act of twisting along an axis |
| toughness |
material resistance to cracking |
| tributary area |
area supported by a structural member |
| tributary width |
width supported by a structural member,
usually a beam, joist or girt |
| truss |
structural member comprised of axially loaded
members arranged in triangular fashion |
| unbraced length |
length between brace point where a member can
buckle |
| weak axis |
axis with lower strength properties,
typically the y-axis |
| weathering steel |
steel that forms a tight oxide layer,
substantially slowing corrosion in non-marine environments |
| welding |
fusion of metals by melting them together,
often with a filler metal |
| wide flange |
I-shaped section, with wide flanges, commonly
used in beams and columns |
| width |
smaller member dimension |
| wind load |
force due to wind |
| yield |
point at which a material has permanent
deformation due to applied loads, start of inelastic region of
stress-strain curve |
