Defintions T - Z

Tapered Members: A built up plate member consisting of flanges welded to a variable depth web.
Tapered Tread Wheels: End truck wheels with treads that are tapered, the large diameter being toward the center of the span.
Tensile Strength: The longitudinal pulling stress a material can bear without tearing apart.
Tension Forces: Forces acting on a member tending to elongate it.
Thermal Block: A spacer of low thermal conductance material, that is installed between the purlin and the roof insulation, to prevent energy loss.
Thermal Conductance (C factor): The time rate of heat flow through unit area of a body induced by unit temperature difference between the body surfaces. Units are BTU (Hour x ft2xdegree F) (Imperial System) or watts/(m2 x degree C) (SI System). See "Thermal resistance".
Thermal Conductivity, (K factor): The time rate of heat flow through unit thickness of a flat slab of a monogenous material in the perpendicular direction to the slab surfaces induced by unit temperature gradient. Units for K are (BTU x in)/(hour x ft2 x degree F) or BTU (hour x feet x degree F) (Imperial System) or watts/(m2 x degree C) (SI System). See "Thermal Resistivity".
Thermal Resistance (R value): Under steady conditions, the mean temperature difference between parallel surfaces of a slab (large enough so there us no lateral heat flow) of unit thickness that induces unit heat flow through unit area. Note: Thermal Resistance and thermal conductance are reciprocals. Thermal resistance are R-values; to obtain the U-factor, overall thermal transmittance, the R-value for either materials or constructions must first be evaluated because, by definition, the U-factor is the reciprocal of the sum of the individual R-values.
Thermal Resistivity: Under steady conditions, the temperature difference between parallel surfaces of a slab (large enough so there is no lateral heat flow) of unit thickness that induces unit heat flow through unit area. Note: thermal resistivity and thermal conductivity are reciprocals. Thermal resistivity is the R-value of a material of unit thickness.
Thermal Transmittance (U-factor): The time rate of heat flow per unit are under steady conditions from the fluid on the warm side of a barrier to the fluid on the cold side, per unit temperature difference between the two fluids. It is evaluated by first evaluating the R-value and then computing its reciprocal.
Through-Fastened Roof System: A roof system in which the roof panels are attached directly to the roof substructure with fasteners which penetrate through the roof sheets and into the substructure.
Through Ties: Reinforcing Steel, usually in the concrete, extending from one column pier to the other column pier, tying the two columns of a rigid frame together to resist thrust.
Thrust: The horizontal component of a reaction usually at the column base.
Tie: A structural member that is loaded in tension.
Ton: 2000 pounds
Track: A metal way for wheeled components; specifically, one or more lines of ways, with fastenings, ties, etc… for a crane way, monorail or slide door.
Transverse: The direction parallel to the main frames.
Tributary Area: The area directly supported by the structural member between contiguous supports.
Trim: The light gauge metal used in the finish of a building, specially around openings at intersections of surfaces. Sometimes referred to as flashing.
Trolley (crane): The unit carrying the hoisting mechanism.
Trolley Frame (Crane): the basic structure of the trolley on which are mounted the hoisting and traversing mechanisms.
Truss: A structure made up of three or more members, with each member designed to carry a tension or compression force. The entire structure in turn acts as a beam.
Turnout: See "Kick-out"
Turn-of-the-Nut Method: A method for Pre-tensioning high strength bolts. The nut is turned from the "snug tight" position, corresponding to a few blows of an impact wrench or the full effort of a man using an ordinary spud wrench, the amount of rotation required being a function of the bolt diameter and length.
Twist off bolts: Bolts with a segment which shears off at a predetermined torque during bolt tightening. These bolts utilized a specially designed wrench for proper installation.

Uplift: Wind load on a building which causes a load in the upward direction.
Valley Gutter: A heavy gauge gutter used for multi-gabled buildings or between buildings.
Vapor Barrier: Material used to retard the flow of vapor or moisture to prevent condensation from forming on a surface.
Ventilator: a roof mounted accessory that allows the air to pass through.
 "W" shape: A hot rolled member with parallel flanges.
Wainscot: Wall material, used in the lower portion of a wall that is different from the material in the rest of the wall.
Walk Door: See "Personnel Door"
Wall Covering: The exterior wall surface consisting of panels
Web: that portion of a structural member between the flanges.
Web Stiffener: See "Stiffener"
Wheel Base: distance from center to center of outermost crane wheels.
Wheel Load: The vertical force without impact produced on a crane wheel bearing on a runway rail or suspended from a runway beam. Maximum wheel load occurs with the crane at rated capacity and the trolley positioned to provide maximum vertical force at one set of wheels.
Width: The dimension of a building measured parallel to the main framing from outside to outside od sidewall girts.
Wind Bent: See "Portal Frame"
Wind Column: A vertical member designed to withstand horizontal wind loads, usually in the endwall.
Wind Load: The load caused by the wind from any horizontal direction.
X-Bracing: Bracing system with members arranged diagonally in both directions to form an "X". See "Bracing".
 "Z" Section:  A member cold formed from steel sheet in the approximate shape of a "Z".
Zinc-Aluminum Coated:  Steel coated with an alloy of zinc and aluminum to provide corrosion resistance