Tapered Members

A built up plate member consisting of flanges welded to a variable depth web.

Tapered Tread Wheels

End truck wheels with treads which 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.

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 feet squared x Fahrenheit)

[Imperial system] or Watts / (mass squared x “Celsius) [SI system]. See “Thermal resistance”.

Thermal Conductivity, (k-factor)

The time rate of heat flow through unit thickness of a flat slab of a homogenous material in the perpendicular direction to the slab surfaces induced by unit temperature gradient. Units for k are (Btu x in) / (hour x feet squared x Fahrenheit) or Btu / (hour x feet x Fahrenheit)

[Imperial system] and Watts / (m x Celsius) [SI system]. See “Thermal resistivity”.

Thermal Resistance (R-value)

Under steady conditions, the mean temperature difference between two defined surfaces of material or construction that induces unit heat flow through unit area. Note: Thermal resistance and thermal conductance are reciprocals. Thermal resistances 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 area 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 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.

Through-Fastened Roof System

A through-fastened roof system is one in which the roof panels are attached directly to the roof substructure with fasteners which penetrate through the roof sheets and into the substructure.

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 craneway, monorail or slide door.

Translucent Light Panels

Panels used to admit light.

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, especially around openings and at intersections of surfaces. Often 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.

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.

Turnout

See “Kick-Out”.

Twist Off Bolts

Bolts with a segment which shears off at a predetermined torque during bolt tightening.

These bolts utilize a specially designed wrench for proper installation.