JOIST AND STRUCTURAL GLOSSARY


A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

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[A]

AASHTO (American Association of State Highway and Transportation Officials)
A regulatory organization which governs the design and specifications of highway bridges.
Accessories
Are extra items that can be furnished in addition to the base joist or joist girder. They include: headers, top chord extensions, extended ends, ceiling extensions, bottom chord extensions, sloped end bearings, bridging, bridging anchors, joist girder bottom chord bracing, or angle units (joist substitutes).
ADL
Abbrevation for 'After Dead Load is Applied'.
Aesthetic
Having the sense of beauty or pleasing to the eye.
AFF
Abbrevation for 'Above Finish Floor'.
AGA (American Galvanizers Association)
A non-profit association representing the post-fabrication hot-dip galvanizing industry.
AGCA (Associated General Contractors of America)
Is a national trade organization of qualified construction contractors and and industry related companies dedicated to skill, integrity, an responsibility. The AGCA is the voice of the construction industry and is dedicated to improving the quality of construction and protecting the public.
AIA (American Institute of Architects)
An organization to unite in fellowship the members of the architectural profession in the United States.
AISC (American Institute of Steel Construction, Inc.)
Is a non-profit technical specifying and trade organization for the fabricated structural steel industry in the United States. It was founded in 1921 with headquarters located in Chicago. One of their best known manuals is the Manual of Steel Construction.
AISE (Association of Iron and Steel Engineers)
Abbreviation.
AISI (American Iron and Steel Institute)
An institute to promote the interests of the iron and steel industry.
Alignment Chart for Columns
A nomograph for estimating the effective length factor, K, of columns in an unbraced frame. Note that the chart is based upon assumptions of idealized conditions which seldom exist in real structures.
Amplitude
A measure of floor vibration. It is the magnitude or total distance traveled by each oscillation of the vibration.
Amplification Factor
A multiplier of the value of moment or deflection in the unbraced length of an axially loaded member to reflect secondary values generated by the eccentricity of the load.
Anchor Bolt
A long 'L' shaped bolt which is set in concrete and used to anchor columns or other members to a foundation or other support.
Anchor Bolt Plan
A plan view showing the size, location, and projection of all anchor bolts.
Anchorage
The process of fastening a joist or joist girder to a masonry, concrete, or steel support by either bolting or welding.
Angle
A hot rolled shape called an Angle with symbol L which has equal legs or unequal legs.
Angle Unit
A member used as a joist substitute which is intended for use at very short spans (10 feet or less) where open web steel joists are impractical. They are usually used for short spans in skewed bays, over corridors, or for outriggers. It can be made up of two or four angles to form channel sections or box sections. Tube and channel sections are also used. See Joist Substitute.
ANSI (American National Standards Institute)
A nonprofit organization which promotes the use of U.S. standards internationally
Apex
The highest point on a joist or joist girder where the sloped chords meet. See also Peak.
Approval Plans
Plans sent by the joist manufacturer to the buyer, engineer, architect, contractor or other person for approval. The plans may include a framing plan, elevations, sections, and a material list.
Area
Unit of measure of length times width expressed in square inches.
Arched Joist
A non-standard type of joist where both the top chord and bottom chord are curved parallel with each other.
Architect
A person who designs buildings or other structures and has completed schooling in building design or similar subjects and is licensed by the state as an architect.
ASCE (American Society of Civil Engineers)
Founded in 1852, is the oldest national professional engineering society in the United States. It is dedicated to the advancement of the individual civil engineer and the civil engineering profession through education.
ASD (Allowable Stress Design)
A structural design method whereby a structural element is designed so that the unit stresses computed under the action of working or service loads do not exceed specified allowable values. See Working Stress Design and Elastic Design.
Aspect Ratio
For any rectangular configuration, the ratio of the lengths of the sides.
ASTM (American Society for Testing and Materials)
An organization which has developed over 10,000 technical standards which are used by industries worldwide.
Atrium
An opening or skylighted lobby through two or more floor levels other than an enclosed stairway, elevator, etc.
AutoCAD
The world's most popular computer-aided drafting software product for the personal computer in both DOS and windows by Autodesk, Inc. Anything that can be drawn on a drawing board can be drawn by AutoCAD.
Automatic Welding
A welding procedure using a machine to make a weld.
Auxiliary Load
Any dynamic live loads such as cranes, monorails, and material handling systems.
AWI (American Welding Institute)
An organization established in 1984 to bridge the gap between the findings of basic welding research and the needs of the industry.
AWS (American Welding Society)
A non-profit organization whose major goal is to advance the science, technology, and application of welding and related joining disciplines.
Axial Force
A force tending to elongate or shorten a member.
Axial Compression
An axial force causing compression in a member.
Axial Load
A load whose line of action passes through the centroid of the member's cross-sectional area and is perpendicular to the plane of the section.
Axial Strut Load
A structural member designed to transfer a axial tension or compression load only.
Axial Tension
An axial force causing tension in a member.

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[B]

Backing Bar
A welding aid used to prevent melting through of a joint when preforming, for example, a complete-joint penetration groove weld.
Balcony
An elevated platform or seating space of an assembly room projecting from a wall of a building.
Ballast Roof
A roof which has selected material, such as crushed stone, placed on its surface to hold down the roof from wind forces.
Bar
A square or round piece of solid steel which is usually 6 inches or less in width.
Base Metal
The metal to be welded or cut.
Base Plate
A steel plate welded to the base of a column which distributes the column loads over an area of foundation large enough to prevent crushing of the concrete and usually secured by anchor bolts.
Basement
Any floor below the first story in a building.
Batten
A small piece of angle or plate welded to the heels of a two angle web member or any two parallel components to tie them together and usually located at the middle of the member.
Bay
The distance between the main frames of a building.
Base Ply
Is one layer of felt fastened to the deck over which a built-up roof is applied.
BBC (Basic Building Code)
A minimum model regulatory code for the protection of public health, safety, welfare and property by regulating and controlling the design, construction, quality of materials, use, occupancy, location and maintenance of all buildings and structures within a jurisdiction.
Beam
A structural member, usually horizontal, whose main function is to carry loads transverse to its longitudinal axis. These loads usually cause bending of the beam member. Some types of beams are simple, continuous, and cantilever.
Beam-Column
A structural member whose main function is to carry loads both parallel and transverse to its longitudinal axis.
Bearing
1) The distance that the bearing shoe or seat of a joist or joist girder extends over its masonry, concrete, or steel support 2) A structural support, usually a beam or wall, that is designed by the specifying professional to carry reactions to the foundation
Bearing Plate
The steel plate used for a joist or joist girder to bear on when they are supported by masonry or concrete supports. This plate transfers the joist reaction to the supporting structure and must be sized accordingly.
Bearing Wall
A wall which is supporting any vertical loads i2n addition to its own weight.
Bending Moment
The condition in the analysis of the internal stresses across the cross section of a member when it is subjected to forces which cause it to bend.
Bending Stress
Is zero at the neutral axis and assumed to increase linearly to a maximum at the outer fibers of the section.
Formula in the elastic range: Bending stress (in psi)=(M * c)/I, where 'M' is the bending moment at the section in in-lbs, 'I' is the moment of inertia of the section in inches^4, and 'c' is the distance from the neutral axis to the point at which the stress is desired in inches.
Bent
The plane of beam or joist girder members which support loads and the columns which support these members.
Bevel Cut
A single cut made at an angle to the member length. See Miter Cut.
BG-Type Joist Girder
A type of Joist Girder where joists are located at all panel points where vertical webs and diagonal webs intersect the top chord.
Biaxial Bending
Bending of a structural member about two perpendicular axes at the same time.
Bifurcation
The phenomenon whereby a perfectly straight member may either assume a deflected position, deflect then twist out of plane, or may remain in an undeflected configuration.
Bill of Lading
A list that gives each part or mark number, quantity, length of material, total weight, or other description of each piece of material that is shipped to a jobsite. The receiver compares each item on this list to what is on the truck and signs the statement. See also Shipping List.
Bill of Materials
A list of items or components used for fabrication and accounting purposes. See Cut-List.
Blasting
A method of cleaning or of roughening a surface by a forceable stream of sharp angular abrasive.
Blue Print
Also called a blue line. Is a copy of an architectural or other drawing made by a special machine usually on white paper with the lines and text being a blue color.
BOCA (Building Officials and Code Administrators International, Inc.)
A minimum model regulatory code for the protection of public health, safety, welfare and property by regulating and controlling the design, construction, quality of materials, use, occupancy, location and maintenance of all buildings and structures within a jurisdiction. Its serves primarily the North Central and Northeast United States.
Bolted Splice
The connection between two structural members joined at their ends by bolting to form a single, longer member.
Bond Beam
The top course of block of a masonry wall filled with concrete and reinforcing steel and used to support roof loads.
Bottom Bearing
A bearing condition where the joist or joist girder bears on its bottom chord and not at an underslung condition.
Bottom Chord
The bottom members of a joist or joist girder.
Bottom Chord Extension (BCX)
The two angle extended part of a joist bottom chord from the first bottom chord panel point towards the end of the joist.
Bottom Chord Strut
A bottom chord of a joist or joist girder designed to transfer a axial tension or compression load.
Boundary Condition
An idealization to model how a structure is attached to its "external" points of support, for example, pin, fixed, roller, or shear release.
Bow String Joist
A non-standard type of joist where the top chord is curved and the bottom chord is straight or level.
Bow's Notation
Used in a graphical analysis of a joist or joist girder. It is a notation for denoting truss joints, members, loads, and forces. Capital letters are placed in the spaces between truss members and between forces. Each member and load is then designated by the letters on opposite sides of it.
Braced Frame
A frame which resists lateral loads by the use of diagonal bracing, K-braces, or other system of bracing.
Bracket
A structural support attached to a column or wall on which to fasten another structural member.
Bridge Crane
A lifting system which has a hoist that moves laterally on a beam or other member which then in turn moves longitudinally on a runway made of beams and rails.
Bridging
In general, is a member connected to a joist to brace it from lateral movement. See Horizontal Bridging and Diagonal Bridging.
Bridging Anchor
An angle or bent plate attached to a wall where the bridging will be attached or anchored, either by welding or bolting. The ends of all bridging lines terminating at walls or beams shall be anchored thereto.
Bridging Clip
A small piece of angle or plate with a hole or slot that is welded to the top and bottom chord angles so that bridging may be attached.
Bridging Diagram
A diagram of the profile of a joist used to show the number and location of the rows of bridging.
Brittle Fracture
The tearing or splitting of a member with little or no prior ductile deformation.
BTU (British Thermal Unit)
The amount of heat required to raise the temperature of one pound of water by one degree farenheit.
Buckling Load
The load at which a straight member under compression transfers to a deflected position.
Building
Any structure used for support or for shelter.
Building Code
Regulations established by a recognized agency describing design loads, procedures, quality of materials, and construction details for buildings for the protection of the public.
Building Designer
A registered architect or registered engineer who is responsible for the design of a structure. See Specifying Professional.
Building Official
The officer or other authority which has the duty of administration and enforcement of a building code.
Built-Up Roof
A type of roof composed of two or more layers of alternating felt, tar and asphalt.
Built-Up Section
A structural member made up from individual flat plates welded together or any structural metal elements that are welded or bolted together.
Butt Plate
The end plate of a structural member usually used to rest or butt against a like plate of another member in forming a connection.

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[C]

C Shapes
A hot rolled shape called an American Standard Channel with symbol C.
"C" Section
A structural member cold-formed from sheet steel in the shape of a block "C" which can be used by itself or back to back with another C Section.
CAD
Abbreviation for Computer-Aided Drafting.
Calipers
A mechanical instrument usually having a pair of pivoted legs adjustable to any distance and used to measure thichness, distances between surfaces, and any internal or external diameter which is inaccessible with a scale.
Camber
Camber is an upward curvature of the chords of a joist or joist girder induced during shop fabrication to compensate for deflection due to loading conditions. Note, this is in addition to the pitch of the top chord.
Canopy
A projecting member that is supported at one end only.
Cant Strip
A deck accessory which is a short piece of gage steel used at 45 degrees where a wall or parapet meets the end of deck.
Canted Seat
A seat which is sloped perpendicular to the member which most joist manufactures do not do. Usually the steel contractor furnishes a bent plate shim to provide level bearing for the seat.
Cantilever
The part of a member that extends freely over a support which is not supported at its end.
Cap Plate
A steel plate welded to the top of a column which a joist, joist girder, or other structural member can bear on.
Catwalk
Suspended structural framing used to provide access to and between areas below a roof and above a floor.
Ceiling Extension
Is similar to a bottom chord extension except that only one angle of the joist bottom chord is extended from the first bottom chord panel point towards the end of the joist.
Centerline Span (or Center-to-Center)
A theoretical span definition which is the distance between the actual centerlines of a beam, column, joist, or joist girder.
Centroid
The point in a member at the intersection of two perpendicular axes so located that the moments of the areas on opposite sides of an axis about that axis is zero.
Certified Welder
A welder who has been certified by a competent experienced welding inspector or a recognized testing facility in the field of welding. The welder must be certified to make certain welds under qualified procedures. The welder must be qualified for each position, type weld, electrode, and thickness of base metal that is to be welded in the shop or field.
Change Order
A written document which modifies the plans, specifications, or price of a construction contract.
Channel
A hot rolled structural shape the looks like "[". There are American Standard Channels designated by (C) and Miscellaneous Channels designated by (MC).
Chord
The two angle top or bottom member of a joist or joist girder, usually with a gap between the angles.
Cladding
The exterior covering of the structural members of a building.
Clear Span
The actual clear distance or opening between supports for a structural member, i.e., the distance between walls or the distance between the edges of flanges of beams.
Clevis
A U-shaped yoke with internal threads in one end which can be attached to a threaded rod and the other end a connection with a hole used for a pin or bolt attchment.
Clip Angle
A structural angle which attaches to the side of a wall, column, beam, etc. where a joist, joist girder, or other structural member bears.
Closure Strip
A floor deck accessory made of gage metal which is placed over the ends of deck so that concrete cannot run out of the flutes of the deck.
Coefficient of (Linear) Expansion
The change in length, per unit, for a change of one degree of temperature.
Cold-Formed
The process of forming a structural section by bending sheet or strip steel in roll-forming machines without the use of heat.
Collateral Load
All additional dead loads other than the weight of the building, such as sprinklers, pipes, ceilings, and mechanical or electrical components.
Column
Is a main vertical member carrying axial loads, which can be combined with bending and shear, from the main roof beams or girders to the foundation. These structural members carry loads parallel to its longitudinal axis.
Column Curve
A curve which shows the relationship between axial column strength and slenderness ratio.
Compact Section
A steel section whose flanges must be continuously connected to the webs and the width-thickness ratios of its compression element can not exceed the limiting width-thichness ratios designated in the AISC Manual.
Composite Beam
A steel beam and a concrete slab connected, usually by shear stud connectors, so that they act together to resist the load on the beam.
Compression
A condition caused by the action of squeezing or shortening of a component.
Compression Member
Any member in which the primary stress is longitudinal compression.
Concentrated Load
A single load or force that has such a small contact area as to be negligible compared with the entire surface area of the supporting member and applied at a certain point on the structure.
Connection
A joint connected by welds or bolts used to transmit forces between two or more members. See also Splice.
Continuity
The term given to a structural system denoting the transfer of loads and stresses from member to member as if there were no connections.
Continuous Span
A span that extends over several supports and having more than two points.
Continuous Weld
A weld which extends continuously from one end of a joint to the other.
Contract
A legal document or agreement, enforceable by law, between two or more parties for the doing of something specified, such as the building of a building or furnishing materials.
Contract Documents
Contract drawings, specifications, etc., used to build a structure which define the responsibilities of the parties involved.
Contract Drawings
All the architectural, structural, mechanical, electrical, etc. plans that make up a legal set of contract documents to build a building by.
Conventional Framing
Framing using conventional joist, beams, columns, masonry walls, etc. instead of framing used in Metal Building construction.
Coping
The process of removing certain sections of a structural steel member to allow easier fitup to the supporting structural member.
Corbel
Successive courses of masonry projecting from the face of a wall to increase its thickness or to form a shelf or ledge for a structural member to bear on.
Cover Plate
A long plate usually welded to the top or bottom flange of a rolled steel beam or to the bottom chord of a joist or joist girder to increase the load carrying capacity of that member.
Coverage
The width of a deck sheet, i.e., 30 inches or 36 inches.
Crane
1) A machine used to move material by means of a hoist. 2) A machine that can usually move and is used to lift heavy materials or to lift members that are to be erected in a structure.
Creep
A time-dependent deformation of a structural member under a sustained constant load.
Cricket
A ridge or drainage diverting roof framing.
Crimped Angle Web
A regular angel whose ends have been 'crimped' in the shape of a 'U' whose out-to-out distance is usually one inch. The actual crimped portion of the angle is only a few inches on each end and the end is inserted between top or bottom chord members to be welded.
Critical Load
The load at which deflection of a member or structure occurs as determined by stability analysis.
CSI (Construction Specifications Institute)
Abbreviation.
Curb
A raised edge of a concrete floor slab or support for a mechanical unit.
Curtain Wall
A non-load bearing exterior wall which carries only its own weight and wind load.
Curvature
The rotation per unit length of a member due to bending forces.
Cut-List
A list of components with dimensions used for fabrication and accounting purposes. See Bill of Materials.

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[D]

Damping
For floor vibrations, it is the rate of decay of amplitude.
Dead Load
Loads due to the weight of the components making up the structure and that are intended to remain permanently in place.
Deck
A floor or roof covering made out of gage metal attached by welding or mechanical means to joists, beams, purlins, or other structural members and can be galvanized, painted, or unpainted.
Deck Type
The specific type of deck to be specified, such as Type "B" Wide Rib, Type "F" Intermediate, Type "N" Deep Rib, Type "A" Narrow Rib, Composite, Cellular, etc.
Deflection
The displacement of a structural member or system under load.
Deformation
The act of distorting or changing the shape or dimensions of a structural element or body resulting from forces or stresses.
Depth of Joist
The out-to-out distance from the top of the top chord to the bottom of the bottom chord taken a some reference location, usually at the midspan of the joist or joist girder.
Design Documents
The plans, details, sections, specifications, etc. prepared by the building designer.
Design Length
The 'span' of a joist or joist girder in feet minus 0.3333 feet.
Design Loads
The loads specified in the contract drawings or specifications which a building is to be designed for.
Design Strength
The resistance provided by a structure, member, or connection to the forces imposed on it.
Diagonal Bracing
Structural members which are inclined and are usually carrying axial load which enable a structural frame to behave as a truss to resist horizontal loads.
Diagonal Bridging
Two angles or other structural shapes connected from the top chord of one joist to the bottom chord of the next joist to form an 'X' shape whose l/r ratio cannot exceed 200. The bridging members are almost always connected at their point of intersection.
Diaphragm
Roof panel or decking, metal wall, or floor slab which provides a larger in-plane shear stiffness and strength adequate to transmit horizontal forces to the resisting structural system.
Diaphragm Action
The resistance to a racking affect or in-plane shear forces offered by roof deck, panels, or other structural members when properly attached to a structural frame.
Double Curvature
When end moments on a structural member produce a bending effect which cause the member to form an S shape or has a reversal in curvature.
Downstanding Leg
The leg of a structural angle which is projecting down from you when viewing.
Drift
The lateral movement or deflection of a structure.
Drift Index
The ratio of the lateral deflection to the height of the building.
Drift Pin
A tapered pin used during the erection process to align holes in steel members which are to be connected by bolting.
Duct
Any tube, pipe or other conduit by which air or fluid is transfered.
Duct Opening
The round or square opening required through the web system of a joist or joist girder to allow passage of a duct.
Ductility
Is the ability of a material to withstand large inelastic deformations without fracture. Structural steel has considerable ductility.
Ductility Factor
The ratio of the total deformation at maximum load to the elastic-limit deformation.
Dynamic Load
A load that varies with time which includes repeative loads, seismic loads, and other loads created by rapid movement.

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[E]

Eave
The line along the sidewall of a building formed by the intersection of the plane of the roof and the plane of the wall.
Eave Height
The vertical distance from finished floor to the eave.
Eave Strut
A structural member located at the eave of a building which supports a roof and/or wall panels.
Eccentric
The condition that exists when a load is applied on a line of action that does not pass through the centroid of the body it is applied to.
Eccentricity
The distance between a line of action of force and the centroid of the member it is applied to.
Edge Angle
1) A structural angle that is connected around the edge of a joist extension or other member 2) An angle used around the sides of a floor to contain the concrete when it is being poured which is also called a Pour Stop.
Edge Distance
The distance from the center of a hole to the edge of a connected part.
Edge Strip
The width or region around the edges of a building where uplift values are higher than in the interior of the roof.
Effective Depth
The distance from the centroid of the top chord to the centroid of the bottom chord.
Effective Length
The equivalent length, KL, used in compression formulas. This method estimates the interaction effects of the total frame on a compression member by using K factors to equate the strength of a framed compression member of length L to an equivalent pin-ended member of length KL subject to axial load only.
Effective Length Factor (K)
The ratio between the effective length and the unbraced length of a member measured between center of gravities of the bracing members. K values are given for several idealized conditions in which joint rotation and translation are realized.
Effective Moment of Inertia
The moment of inertia of the cross section of a member that remains elastic when partial plastification takes place. See Moment of Inertia.
Effective Width
The transverse distance indicating the amount of slab that acts in conjuction with the supporting member.
EJ
Abbrevbation for 'Expansion Joint'.
Elastic Analysis
The analysis of a member which assumes that material deformation disappears on removal of the force that produced it and the material returns to its original state.
Elastic Design
See Allowable Stress Design and Working Stress Design.
Electrode
The device through which current is conducted thru to the arc or base metal during the process of welding.
Embedment
A steel member such as a plate, bolt, stud, or bar cast into a concrete structure which is used to transmit applied loads to the concrete.
End Bay
The bay which is located from the end of a building to the first interior main frame.
End Diagonal or Web
The first web member on either end of a joist or joist girder which begins at the top chord at the seat and ends at the first bottom chord panel point.
End Distance
The horizontal distance from the first top chord panel point at the end of a joist to the first bottom chord panel point.
End Lap
The lap at the end of a sheet of deck which bears over the primary support (joist or beam).
End Moment
A moment which is generated at one end or both ends of a joist, joist girder, or beam due to continuous frame action which can be caused by wind, live load, or dead load moment.
End Panel
The distance from the panel point at thejoist seat to the first top chord panel point towards the interior.
End Wall
An exterior wall which is perpendicular to the ridge of the building.
Envelope
A graphical plot indicating the maximum magnitude of an internal force effect such as flexual stess, shear stress, axial stress, torsional stress, etc. due to a series of load combinations.
EOD
Abbreviation for 'Edge of Deck'.
EOJ
Abbreviation for 'Edge of Joist'.
EOS
Abbreviation for 'Edge of Slab'.
Equations of Equilibrium
The equations relating a state of static equilibrium of a member or structure when the resultant of all forces and moments are equal to zero. Three equations must be fulfilled simultaneously: Sum of the forces in the X-direction must equal zero, sum of the forces in the Y-direction must equal zero, and the sum of the moments about any point must equal zero for a two dimensional structure.
Equivalent Uniform Load
A uniform load (in plf) derived from the maximum reaction (in lbs) or the maximum moment (in inch-lbs) of a member carrying various loads.
Formula: Weq= 2 * max. reaction (in lbs) divided by length (in feet) or
Weq=(8 * max. moment) divided by (lenght^2 (in feet) * 12)
Erection
The process of installing joists, joist girders, beams, bridging, deck, or other structural members in order to construct a structure.
Erection Plan
Floor or roof plans that identify individual marks, components, and accessories furnished by the joist manufactures in a detailed mannner to permit proper erection of the joist and joist girders. See Framing Plan and Placing Plan.
Erector
The person or company that actually does the erecting of the joist or joist girders for a job.
Expansion Joint
A break in construction or a special design detail to allow for thermal expansion and contraction of the materials of a structure.
Extended End
The extended part of a joist top chord with also the seat angles extended from the end of the jost extension back into the joist maintaining the standard 2 1/2 inch end bearing depth over the entire length of the extension.

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[F]

Fabrication
The manufacturing process to convert raw materials into a finished product by cutting, punching, welding, cleaning, and painting.
Factor of Safety
Is the ratio of the ultimate load for a member divided by the allowable load for a member and must always be greater than unity.
Factored Load
The product of the nominal load and a load factor.
Farside
For joists and joist girders, when looking at the member with the tagged end to the right, it is the side that is opposite the side you see first.
Fascia
The flat surface located at the outer end of a roof overhang or cantilever end or also a decorative trim or panel which projects from the face of a wall.
Fastener
Term for a connecting device such as a weld, bolt, rivet, etc.
FC
Abbreviation for 'Field Cut'.
Field
A term used for the jobsite or building site where construction of the project will take place.
Field Weld
The specific term used for the welding of structural members out at the actual jobsite and not in a fabricators shop.
Filler
A rod, plate, or angle welded between a two angle web member or between a top or bottom chord panel to tie them together usually located at the middle of the member. See Tie or Plug.
Finish
In deck terminology, the coating on the deck sheet, i.e., galvanized, painted, or unpainted.
Finish Strip
A roof deck accessory made out of gage metal for finishing out runs of deck for small areas of coverage where full sheet coverage is impractical.
Fire Proofing
The process of coating a structural steel member with a fire retardant material to make the member resistant to fire.
Fire-Resistance
The ability of a joist or other structural member to resist a fire due to the type of protection it has, such as membrane protection or spray on protection. There are hundreds of floor-ceiling or roof-ceiling assemblies with their fire-resistance rating given in the Underwriters Laboratory Fire Directory.
Fixed-End Support
A condition where no rotation or horizontal or vertical movement can occur at that end. This type of support has no degrees of freedom. Three reactive forces exist at the rigidly fixed end. See also Rigid Connection.
Flange
The projecting edge of a structural member.
Flange Brace
A structural bracing member used to provide lateral support to the flange of a beam, the bottom chord or a joist girder, or a column.
Flashing
Pieces of sheet metal or the like used to cover and protect joints, etc. where a roof comes in contact with a wall or chimney.
Flute
The fold or bend in a sheet of deck which forms a groove or furrow.
FMS (Factory Mutual System)
A leader in property loss prevention engineering and adjustment. It helps companies prevent and control property loss through research, engineering, and education.
Folding Partition
A moveable wall on a track suspended from a joist or beam which usually folds like an accordion and can be stored in a closet or pocket in a wall.
Footing
A concrete pad or mat located under a column, wall, or other structural member that distributes loads from that member into the supporting soil.
Foundation
The substructure which supports a building or other structure.
Frame
A structural framing system consisting of members joined together with moment or rigid connections which maintain their original angular relationship under load without the need for bracing in its plane. See Rigid Frame.
Framed Opening
Headers or other structural members which surround an opening in a roof which can be for mechanical units, straiwells, etc.
Framing Plan
Floor or roof plans that identify individual marks, components, and accessories furnished by the joist manufactures in a detailed mannner to permit proper erection of the joist and joist girders. See Erection Plan and Placing Plan.
Free-Body Diagram
A diagram on which all of the external forces acting on a body are shown at their respective points of application.
Frequency
A measure of floor vibration. It is the speed of the oscillations of vibration and is expressed in cycles per secong or Hz (Hertz).

[Return to Glossary]

[G]

G-Type Joist Girder
A type of Joist Girder where joists are located at panel points where diagonal webs intersect the top chord only.
Gable
The triangular portion of a roof located above the elevation of the eave line of a double sloped roof.
Gable Joist
A non-standard type of joist where the top chord is double pitched at an extreme pitch (say 3/12) and the bottom chord is straight or level.
Gage
1) The thickness of a sheet of deck or 2) The distance from centerline hole to centerline hole across a set of holes, usually perpendicular to the joist or joist girder.
Galvanized
The process of coating steel with zinc for corrosion resistance.
Gambrel
A roof having two slopes on each side, the lower slope usually steeper than the upper one.
Girder
A main horizontal, primary structural member spanning between two main supports which carries other members or vertical loads.
Girt
A horizontal structural member that is attached to the sidewall or endwall columns supporting sheeting or paneling.
Grade
The ground elevation around a building.
Grillage Beam
A short beam used like a bearing plate to distribute large reactive loads to a wall such as the load from a joist girder.
Gusset Plate
A steel plate used to connect structural steel members or to reinforce members. It is usually inserted between the top or bottom chord of a joist or joist girder.

[Return to Glossary]

[H]

H-Series Joist
A series of joist adopted in 1961 so proportioned that the allowable tension or bending stress does not exceed 22,000 psi or 30,000 psi depending on whether 36 ksi or 50 ksi yield steel was used.
Hardness
Is a measure of the resistance of a material to scratching and indention.
Header
A structural member located between two joists or between a joist and a wall which carries another joist or joists. Usually made up of an angle, channel, or beam with saddle angle connections on each end for bearing.
Heel
The outside point of a structural angle where the two perpendicular legs intersect.
High Strength Bolts
A structural steel bolt having a tensile strength greater than 100,000 pounds per square inch, usually A325 or A490.
High Strength Steel
Structural steel having a yield stress greater than 36,000 pounds per square inch.
Hinge Support
This type of support has one degree of freedom, it can freely rotate about its axis but it cannot displace in any direction. Two mutually perpendicular reactive forces exist at the hinge and their lines of action pass through the center of the hinge. See Pin Connection or Support.
Hip Roof
A roof which slopes from all four sides of a building. The line where two adjacent sloping sides intersect is called the 'hip'.
Hip and Valley
A system of roof framing where support members form valleys and ridges.
Hoist
A chain or electric lifting device usually attached to a trolly which travels along a monorail or bridge crane.
Homogeneous Material
A material having the same engineering design properties throughout.
Hooke's Law
The linear relationship of forces and deformations, or stresses and strains.
Horizontal Bridging
A continuous angle or other structural shape connected to the top and bottom chord of a joist horizontally whose l/r ratio cannot exceed 300.
Horizontal Shear Stress
Is zero at the outer fibers of a section and is maximum at the neutral axis. It tends to cause one part of the section to slide past the other.
Formula: Horizontal Shear stress (in psi)=(V * Q)/I*t, where 'V' is the external vertical shear on the section in lbs, 'I' is the moment of inertia of the section in inches^4, 'Q' is the statical moment about the neutral axis of the entire section of that portion of the cross-section lying outside of the cutting plane and 't' is the width at the cutting plane.
Hot-Rolled Shapes
Structural steel sections which are formed by rolling mills from molten steel which can be angles, channels, W Shapes, S Shapes, etc.
HP Shapes
A hot rolled shape with symbol HP used for bearing piles which have essentially parallel flanges and equal web and flange thickness.
Hysteresis
A term that describes the behavior of a structural member subjected to reversed, repeated load into the inelastic range whose plot of load verses displacement is characterized by loops. The amount of energy dissipated during inelastic loading is indicated by the enclosed area within these loops.

[Return to Glossary]

[I]

ICBO (International Conference of Building Officials (Uniform Building Code)
A minimum model regulatory code dedicated to public safety through development and promotion of uniform codes and standards.
Ice Dam
A dam or blockage formed on a roof by the buildup of ice along the eave of a building.
IFI (Industrial Fasteners Institute)
Abbrreviation.
III (Institute of the Ironworking Industry
Abbreviation.
Impact Factor
The factor by which the static weight is increased by dynamic application.
Impact Load
A weight that is dropped or a dynamic load generated by movement of a live load such as vehicles, craneways, etc.
Impact Strength
The ability of a material to absorb the energy of a load delivered rapidly to a member.
Impact Wrench
A pneumatic device used to tighten nuts on bolts.
Inclusions
Nonmetallic material which is entrapped in sound metal.
Inelastic Action
Deformation of a material which does not disappear when the force that produced it is removed.
Inflection Point
Represent a point of zero moment in structural member.
Influence Line
An influence line is a curve whose ordinates give the values of some particular function (shear, moment, reaction, etc.) in an element due to a unit load acting at the point corresponding to the particular ordinate being considered. Influence lines for statically determinate structures are straight lines and for statically indeterminate structures the lines are curved and their construction involves considerable analysis.
Instability
A condition reached when a structure or structural member is loaded in which continued deformation results in a decrease in its load-resisting capacity.
Insulation
Any material used to reduce heat transfer in a roof or building.
Intermittent Weld
A weld which is not continuous. It is broken by recurring unwelded spaces.
Internal Pressure
The pressure inside a building which is a function of the wind velocity and the number and locations of openings.
Interior Bearing
Bearing supports which are interior to two exterior supports.
ISO 9000 (International Organization for Standardization)
Is a series of quality management and assurance standards for companies to strive for.
Isotropic
A material having equal physical properties along all axes.

[Return to Glossary]

[J]

J-Series Joist
A series of joist adopted in 1961 so proportioned that the allowable tension or bending stress does not exceed 22,000 psi and was made from A36 steel.
Jack Truss
A joist girder that is supporting another joist girder.
JBE
Abbreviation for 'Joist Bearing Elevation'.
Jib Crane
A cantilevered boom or beam with a hoist and trolly used to pick up loads in all or part of a circle around which it is attached
Jig
A device which holds work or pieces of materal in a certain position until rigidly fastened or welded during the fabrication process.
Jobsite
The specific location where a structure is being build.
Joint
The area where two or more ends or surfaces are joined by a weld or other fastener. See Panel Point.
Joint Penetration
The minimum depth the weld metal extends from its face into a joint.
Joist
A structural load-carrying member with an open web system which supports floors and roofs utilizing hot-rolled or cold-formed steel and is designed as a simple span member.
Joist Designation
A standard way of communicating the joist safe uniformly distributed load-carrying capacities for a given span such as 16K5 or 24K10 where the first number is the nominal joist depth at midspan and the last number is the chord size. See Longspan Designation and Joist Girder Designation.
Joist Girder
A primary structural load-carrying member with an open web system designed as a simple span supporting equally spaced concentrated loads of a floor or roof system acting at the panel points of the joist girder and utilizing hot-rolled or cold-formed steel.
Joist Girder Designation
A standard way of communicating the girder design loads such as 48G6N10.5K where the first number is the nominal girder depth at midspan, 6N is the number of joist spaces on the span of girder, and 10.5K is the kip load on each panel point of the girder. The approximate dead load weight of the member is included in the kip load. See Joist Designation and Longspan Designation.
Joist Manufacturer
The producer of joists or joist girders who is SJI approved.
Joist Spacing
The distance from one joist to another.
Joist Substitute
A structural member which is intended for use at very short spans (10 feet or less) where open web steel joists are impractical. They are usually used for short spans in skewed bays, over corridors, or for outriggers. It can be made up of two or four angles to form channel sections or box sections. See Angle Unit.

[Return to Glossary]

[K]

K-Distance
The distance from the outside fiber of a rolled steel beam to the web toe of the fillet of a rolled shape.
K-Series Joist
A series of joist adopted in 1986 based on a load/span type of determination.
KCS Joist
Is a K-Series joist that is designed to support uniform load plus concentrated loads or other non-uniform loads.
Kerf
The width of a cut produced during a cutting process.
Key Plan
A small reference plan or outline of the whole building on each plan sheet divided into smaller areas for which each sheet is drawn. It can also show different sequences, phases, sheet number that area is drawn on, etc.
Kicker
A structural member used to brace a joist or beam usually at an angle.
Kilo
SI prefix for 10^3 or 1000.
Kip
A unit of weight equal to 1000 pounds.
Knee Brace
A structural brace positioned diagonally between a beam or column and a joist panel point.
Knife Plate Seat
A vertical plate used as a joist seat whose width is small for bearing purposes. It is used for hip and valley bearing conditions, canted seat conditions, and extreme skewed conditions.
KSI (Kips per Linear Foot)
Is 1000 pounds per square inch.
KSF (Kips per Square Foot)
Is 1000 kips per square foot.

[Return to Glossary]

[L]

Lamellar Tearing
Is a separation or crack in the base metal caused by through-thickness weld shrinkage strains of adjacent weld metal.
Lap Joint
Lateral Buckling
Also called lateral-torsional buckling. This is buckling of a member involving lateral deflection and twist.
Lateral Bracing
Members, fasteners, or welds which brace a member at certain locations to prevent lateral movement.
Lean-To
A structure depending upon another structure for support and having only one slope such as a shed.
Leeward
The direction toward which the wind is blowing, which is opposite the side from which the wind blows. Opposite of windward.
Leg
The flat projecting part of a structural angle.
Leveling Plate
A steel plate used on top of a foundation on which a structural column can be placed.
Lintel
A horizontal structural member spanning a door, window, or other wall opening which supports a wall or any construction immediately above.
Live Load
Loads on a member that are not permanent and are likely to be moved at some point in the life of the structure. They can be loads produced by the use and occupancy of the building. These loads do not include dead load, wind load, snow load, or seismic load.
Load
An external force or other action acting on a member or structure. It can be from permanent construction, environmental effects, differential settlement, occupants, and material objects.
Load Combination
The combination of loads which produce the worse loading condition in a structural member.
Load Table
A table of standard joist designations which give the total safe uniformly distributed load-carrying capacities and live load-carring capacities of the joists for different span lengths. The table also gives the approximate weight per foot of each joist designation.
Loading Diagram
A diagram which shows all design loads and design criteria that a member is to be designed for. The loads include: dead load, live load, snow drift, concentrated loads, moments, etc. The design criteria include: deflection requirements, load combinations, net uplift, one-third increase in allowable stress allowed or not, etc.
Longitudinal
The direction extending along the long axis of the member.
Longspan Designation
A standard way of communicating the longspan joist safe uniformly distributed load-carrying capacities for a given clear span such as 18LH06 or 36LH10 where the first number is the nominal joist depth at midspan and the last number is the section number. See Joist Designation and Joist Girder Designation.
Longspan Joist
A structural load-carrying member with an open web system which supports floors and roofs utilizing hot-rolled or cold-formed steel and is designed as a simple span member. These carry higher loads than a regular joist.
Loose Angle Strut
A single or double angle either welded or bolted at the first bottom chord panel point and extended to brace another member such as a beam, joist girder, frame, or wall.
LRFD (Load and Resistance Factor Design)
A method of proportioning structural members such that no limit state is exceeded when all appropriate load combinations have been applied.

[Return to Glossary]

[M]

M Shapes
A hot rolled shape called a Miscellaneous Shape with symbol M that cannot be identified as W, HP, or S Shapes.
Major Axis
The axis of a structural member possessing the largest section modulus and radius of gyration, thus having the greatest flexural and axial compressive strength.
Mark
An identification number or method of relating to the erector which joist, joist girder or other separate part of the building goes at what location when being erected, i.e., J1, K25, L7, G12, or JG9. See Piece Mark and Part Number.
Masonry
A type of construction from materials such as concrete blocks, bricks, concrete, stone, or ceramic blocks which is laid unit by unit and set in mortar.
Maxwell Diagram
A graphical method of determining stresses in a truss by combining force polygons of all the joints into one stress diagram.
MBMA (Metal Building Manufacturers Association)
An association of manufacturers of metal building systems whose objectives are to compile and publish recommended design standards which will insure high quality metal buildings.
MC Shapes
A hot rolled shape called a Miscellaneous Channel with symbol MC.
Mechanical Unit
An air conditioner or other unit either placed on top of a roof system or hung below which applies loads to joist or joist girders.
Mega
SI Prefix for 10^6 or 1000000.
Member Release
An idealization to model how members are attached to "each other". It designates whether forces and moments at the ends of a member are considered fixed to or released from the member's point of attachment.
Metal Building System
A building system consisting of a group of coordinated components which have been designed for a certain loading. These components are mass produced and assembled in various combinations with other structural materials to produce a building.
Metal Stud
A structural steel member used for framing walls just as a regular wooden one.
Meuller-Breslau Principle
Is a simple method to draw approximate shapes of influence lines.
Mezzanine
A low floor between two stories in a building, usually just above the ground floor.
MHI (Material Handling Industry)
Is a not-for-profit organization which was formed to advance the interests of the material handling industry which includes the movement, storage, control, and protection of material and products throughout the process of their manufacture, distribution, consumption, and disposal.
Mil
A measurement of thickness of paint. One mil=.001 of an inch.
Milled
A surface which has been accurately sawed or finised to a true plane.
Mill Test Report
A report of a heat of steel that indicates the customer's order number, grade of steel, number and dimensions of pieces shipped, and the chemical compositional makeup of hot rolled structural steel members. It also indicates physical properties, such as, yield strength, tensile strength, elongation, impact, and ultimate strength.
Milli
SI prefix for 10^-3 or 0.001
Minor Axis
The axis of a structural member possessing the smallest section modulus and radius of gyration, thus having the least flexural and axial compressive strength.
Miter Cut
A single cut made at an angle to the member length. See Bevel Cut.
Modulus of Elasticity (E)
Is the slope of the straight-line portion of the stress-strain curve in the elastic range found by dividing the unit stress in ksi by the unit strain in in/in. For all structural steels, the value is usually taken as 29,000 ksi. This is also called Young's Modulus.
Moment
The tendency of a force to cause a rotation about a point or axis which in turn produces bending stresses.
Moment Connection
A connection designed to transfer moment as well as axial and shear forces between connecting members.
Moment Diagram
A diagram that represents graphically the moment at every point along the length of a member.
Moment of Inertia (I)
A physical property of a member which helps define rigidity or stiffness and is expressed in inches raised to the fourth power. It is a measure of the resistance to rotation offered by a section's geometry and size.
Moment Plate
A welded steel plate used to develop a rigid connection to the supporting member so that moment transfer can occur.
Monorail
Usually a single rail support for a material handling system.
MPC (Materials Properties Council)
Abbreviation.
MT
A hot rolled structural tee shape with symbol MT which is cut or split from M Shapes.
Mullion
A vertial member or division between the panels of a window.
Mylar
A type of strong, thin polyester sheet used for producing blueprints of architectural drawings.

[Return to Glossary]

[N]

Nailers
Strips of lumber attached to the top chord of a joist so plywood or other flooring can be nailed at 36 inches maximum on center.
NBC (National Building Code)
A minimum model regulatory code for the protection of public health, safety, welfare and property by regulating and controlling the design, construction, quality of materials, use, occupancy, location and maintenance of all buildings and structures within a jurisdiction.
NBS (National Bureau of Standards)
Abbreviation.
NCEES (National Council of Examiners for Engineering and Surveying)
Provides leadership in professional licensure of engineers and land surveyors.
NEA (National Erectors Association)
Abbreviation.
Nearside
For joists and joist girders, when looking at the member with the tagged end to the right, it is the side you see first and is closest to you.
Neutral Axis
The surface in a member where the stresses change from compression to tension, i.e., represents zero strain and therefore zero stress. The neutral axis is perpendicular to the line of applied force.
Newton
The SI unit of measure for force (N).
NFPA (National Fire Protection Association)
An international nonprofit organization to reduce the burden of fire on the quality of life by proposing codes and standards, research, and education on fire related issues.
NIC
Abbreviation for 'Not in Contract'.
NIST (National Institute of Standards and Technololgy)
An organization that works with industry and government to advance measurement science and develop standards.
Non-Bearing Wall
A wall that supports no vertical load other than its own weight.
Noncompact Section
A steel section which does not qualify as a compact section and the width-thickness ratios of its compression elements do not exceed the values designated in the AISC Manual.
Nonrigid Structure
A structure which cannot maintain its shape and may undergo large displacements and would collapse under its own weight when not supported externally.
NRCA (National Roofing Contractors Association)
Abbreviation.
NSPE (National Society of Professional Engineers)
Abreviation.
NTS
Abbreviation for 'Not to Scale'.

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[O]

Offset Ridge
When the ridge of a joist that has the top chord pitched two ways is not in the center of the member or bay.
On The Flat
A measurement of distance horizontally on a plan, no slopes involved.
One-third Increase
When designing steel members for forces produced by wind or seismic conditions, the allowable stresses in the design formulas may be increased 1/3 above the values otherwise provided.
OSHA (Occupational Safety and Health Administration)
A federal organization whose purpose is to save lives, prevent injuries, and protect the health of the workers of America.
Outrigger
A structural member which is usually perpendicular to a joist and attaches under the outstanding leg of one of the joist top chord angles. It then bears on a beam or wall and cantilevers across, similar to a top chord extension.
Outstanding Leg
The leg of a structural angle which is projecting toward or away from you when viewing.
Overhang
The extension of the top chord of a joist beyond the outside of the bearing support. See Top Chord Extension.

[Return to Glossary]

[P]

P-Delta Effect
The secondary effect of column axial loads and lateral deflection on the moments in structural members.
Pack Out
When joists are erected in multiple bays, they begin to hit each other end to end (or pack out) because the center to center of beam is not true or the joists are to long.
Panel or Panel Length
1) The distance between two adjacent panel points of a joist or joist girder 2) A sheet of deck for a roof or floor.
Panel Point
The point where one or more web members intersect the top or bottom chords of a joist or joist girder. See Joint.
Parallel Chord
Type of joist or joist girder which has its top and bottom chords parallel to each other. The member can be sloped and still have parallel chords.
Parapet
The portion of a vertical wall of a building which extends above the roof line at the intersection of the wall and roof.
Part Number
See Mark and Piece Mark.
Partially Restrained
A type of connection that displays a moment rotation behavior that can neither be described as pinned nor fixed.
Partition
A wall that is one story or less in height used to subdivide the interior space in a building and can be a bearing wall or a non-bearing wall.
Pascal
The SI unit of measure for stress or force per unit area (N/m^2).
PE
Abbreviation for 'Professional Engineer'.
Peak
The highest point of a gable or also the highest point on a joist or joist girder where the sloped chords meet. See also Apex.
Penthouse
A small enclosed structure above the roof of a building.
Permit
An official document or certificate by a governmental agency or building official authorizing performance of a building process or other specified activity.
Piece Mark
See Mark and Part Number.
Pilaster
A reinforced or enlarged portion of a masonry wall to provide support for vertical roof loads or lateral loads on the wall.
Pin Connection or Support
A connection where no moment is transfered from one member to another, only axial and shear forces. This type of support has one degree of freedom, it can freely rotate about its axis but it cannot displace in any direction. Two mutually perpendicular reactive forces exist at the pin and their lines of action pass through the center of the pin. See Hinge Support.
Pipe
A hollow cylinder of metal used for the conveyance of water or gas or used as a structural column which comes in sizes of standard, extra strong and double-extra strong.
Pipe Bridge
A structural system where two joists are used to carry loads such as piping or ducts. The two joists have to have diagonal bridging and their top and bottom chords have to be laced together with structural members to provide stability for the whole structure,
Pitch
Is the slope or inclination of a member. It is defined as the ratio of the total rise to the total width. It also is defined as the angle that the top chord makes with the lower chord. There can be single or double pitched members.
Placing Plan
See Erection Plan and Framing Plan.
Plan North
The North arrow symbol on a contract drawing usually 90 degrees to the longitudinal axis of the plan so that communication will be easier for the elevations of the building, sections, etc.
Plane Frame
A two-dimensional structural framework.
Plastic Design
A design concept based on multiplying the actual design loads by a suitable load factor and then using the yield stress as the maximum stress in any member.
Plate
A thin, flat piece of metal of uniform thickness usually over 8 inches to 48 inches in width.
Plate Girder
A built-up structural beam.
PLF (Pounds per Linear Foot)
A unit of load obtained by multiplying pounds per square foot times the tribituary width on a joist.
Plug
A rod, plate, or angle welded between a two angle web member or between a top or bottom chord panel to tie them together usually located at the middle of the member. See Tie or Filler.
Plug Weld
A weld in a slot in a piece of steel which overlaps another piece. A principle use for a plug weld is to transmit shear in a lap joint. See Slot Weld and Puddle Weld.
Poisson's Ratio
Defined as the ratio of the unit lateral strain to the unit longitudinal strain. It is constant for a material within the elastic range. For structural steel, the value is usually taken as 0.3. It gradually increases beyond the proportional limit, approaching 0.5.
Polar Moment of Inertia (J)
Is the sum of any two moments of inertia about axes at right angles to each other. It is taken about an axis which is perpendicular to the plane of the other two axes.
Ponding
The gathering of water at low or irregular areas on a roof.
Portal Frame
A rigid frame structure which is designed to resist longitudial loads where diagonal bracing is not permitted. It has rigidity and stability in its plane.
Pounds (LB or #)
A unit of weight.
Pour Stop
An angle used around the sides of a floor to contain the concrete when it is being poured.
Powder Actuated
A fastening method which uses a powdered charge to imbed the fastener into the member.
Prefabricate
To manufacture or construct parts or sections of structural assemblies beforehand that are ready for quick assembly and erection at a jobsite.
Press Brake
A machine used in cold-forming metal sheet or strip into a desired cross section or structural shape.
Primary Members
This is the main load carrying members of a structure such as a beam or joist girder.
Principle of Superposition
States that the resultant is the algebraic sum of the effects when applied separately.
Primer or Paint
The initial coating of a member applied in the shop which is not a finish coat and only protects from rust for a limited time.
Prismatic Beam
A beam with uniform cross section.
Profile Drawing
A drawing or diagram which shows the outline of a joist with dimensions and also maybe the web system configuration and bridging rows. See Side-View Diagram
Proportional Limit
The point on a stress-strain curve where the linear relationship between stress and strain ends and usually coincides with the material yield point.
PSI (Pounds per Square Inch)
A unit of stress or pressure.
PSF (Pounds per Square Foot)
A unit of stress which to multiply the tribituary width on a joist by to get PLF.
Puddle Weld
See Plug Weld.
Purlin
Usually a cold-formed horizontal structural member attached perpendicular to the joist top chord or main frames of a building for support of the roof deck.

[Return to Glossary]

[Q]

****
No terms yet!

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[R]

Radius of Gyration (r)
Is the distance from the neutral axis of a section to an imaginary point at which the whole area of the section could be concentrated and still have the same moment of inertia.
Formula: The square root of (the moment of inertia in inches^4 divided by the area of the section in inches^2) expressed in inches.
Rafter
The main beam supporting a roof system or a sloping roof framing member.
Rake
The edge of a roof which intersects the gable part of a roof.
RCSC (Research Council on Structural Connections)
Abbreviation.
Reaction
The force or moment developed at the points of a support.
Redundants
The reactions which are not necessary for static equilibrium.
Reinforcement
An additional member added to a structural member to provide additional strength.
Reinforcing
The process of strengthening a member with some additional piece of material.
Relaxation
Is a decrease in load or stress of a member under a sustained constant deformation.
Repair
The reconstruction or renewal of any part of an existing structure or building for the purpose of its maintenance.
Residual Stress
Pre induced stresses within a structural member due to uneven cooling of the shape after hot-rolling.
Resistance
The capacity of a structure or structural member to resist the effects of loads or forces imposed on it.
Retaining Wall
A wall designed to resist the lateral displacement of soil, water, or any other type of material.
Rib
A fabricated fold or bend in a sheet of deck which projects up from a horizontal plane.
Ridge
The highest point on the roof of a building formed by two intersecting slopes or the horizontal line made by the top surfaces of the two intersecting sloping roof surfaces.
Rigid Connection
A connection where moment is transfered from one member to another. See also Fixed-End Support.
Rigid Frame or Structure
A structural framing system consisting of members joined together with moment or rigid connections which maintain their original angular relationship under load without the need for bracing in its plane. See Frame and Stability.
Rise
The vertical distance from the bottom to the top of an entity.
RMI (Rack Manufacturers Institute)
An institute organized in 1958 by industry leaders as a not-for-profit trade association. Its mission is to advance standards, quality, safety, and general fitness for intended use of industrial steel storage rack systems.
Rod
A smooth solid round bar used for the web system of a bar joist.
Roof Covering
The exposed exterior roof skin of a building which can be sheets, panels or other materials.
Roof Overhang
A roof extension that projects beyond the ends or sides of a building.
Roller Support
This type of support has two degrees of freedom, it can freely rotate about its axis or displace in one direction in the plane. Only one reactive force exists at a roller which acts perpendicular to the path of the displacement and its line of action passes through the center of the roller.

[Return to Glossary]

[S]

S Shapes
A hot rolled shape called an American Standard Beam with symbol S.
Saddle Angle
The angle connection or seat on the end of a header or frame which bears from the side on the top chord of a joist. This angle should be designed to carry the reaction of the header or frame to the center of the joist and must rest on and weld to both top chord angles.
Sag Rod
A tension member used to limit the deflection of a girt or purlin in the direction of the weak axis.
SBC (Standard Building Code)
A minimum model regulatory code for the protection of public health, safety, welfare and property by regulating and controlling the design, construction, quality of materials, use, occupancy, location and maintenance of all buildings and structures within a jurisdiction.
Scab On
A member fastened or welded to another member for reinforcement.
Scissor Joist
A non-standard type of joist where both the top chord and bottom chord are double pitched and parallel with each other.
Scupper
Any opening or drain in the side of a structure, flat roof, or downspout for the drainage of rain water.
Scuttle
A framed opening in a roof used for access to the roof from inside a building.
SDI (Steel Deck Institute)
An institute which brings uniformity to the design, manufacture, quality control, and construction practices applicable to cold-formed steel deck.
SEAA (Steel Erectors Association of America)
An organization that sets uniform standards among the many steel erectors and helps promote safety in the erection industry.
Seat Depth
The out-to-out depth of the end bearing shoe or seat of a joist or joist girder which is the distance from the top of the top chord to the bottom of the bearing seat angle or plate.
Section Modulus (S)
A physical property of strength of a structural member. It relates bending moment and maximum bending stress within the elastic range. Formula: S=I/c where 'I' is the moment of inertia of the cross-section about the neutral axis in inches^4 and 'c' is the distance from the neutal axis to the outermost fibers.
Seimic Load
Are assumed lateral forces acting in any horizontal direction that produce stresses or deformations in a structural member due to the dynamic action of an earthquake.
Self Tapping Screw
A mechanical fastener for attaching deck, panels, or other materials to a structure which taps its own threads in a predrilled hole.
Sequence
A breakdown of when materials are to be made or delivered for a project with one following after the other.
Set Back
The distance from the outside edge of an angle or other member to the edge of a gusset plate or angle welded near the end.
Shaft
An interior space, enclosed by walls, which extends through one or more stories or basement which connects successive floors and/or roof for elevators, dumbwaiters, mechanical equipment, etc.
Shape Factor
The ratio of the plastic section modulus Z to the elastic section modulus S or the ratio of the plastic moment Mp to the yield moment My.
Shear
A condition or force causing two contacting parts of a material to slide past each other in opposite directions parallel to their plane of contact.
Shear Center
The point in a cross section of a structural member to which a load may be applied and not induce any torsional stress in the cross section.
Shear Diagram
A diagram that represents graphically the shear at every point along the length of a member.
Shear Release
A boundary condition which constrains a member end from axial displacement and rotation but allows movement in a direction perpendicular to the members longitudinal axis.
Shear Stud Connector
A steel device used in composite design which is welded to the top flange of a beam or top chord of a joist which transfers shear from a concrete slab to the supporting member.
Shear Wall
A wall that resists horizontal shear forces applied in the plane of the wall.
Shim
A piece of steel used to level a joist seat. It can be a bent plate, flat plate or rod.
Shipping List
A list that gives each part or mark number, quantity, length of material, total weight, or other description of each piece of material to be shipped to a jobsite. See also Bill of Ladding.
Shop Drawings
1) Can also be called the erection plans or framing plans 2) The actual drawings used by a shop to fabricate a product which includes all dimensions, materials, tolerances, etc.
Shore
The process of temporarily supporting a structure or structural member with auxiliary members.
SI (Le Systeme International d'Unites)
The international abbreviation for the International System of Units or metric system.
Side Lap
The lap at the sides of a sheet of deck and is attached by side lap screws or welds between supports.
Side Lap Screws
A screw used to connect the sides of two adjacent sheets of deck together, #10 being the standard size.
Side-View Diagram
A drawing or diagram which shows the outline of a joist with dimensions and also maybe the web system configuration and bridging rows. See Profile Drawing.
Side Wall
An exterior wall which is parallel to the ridge of the building.
Sidesway
The lateral movement of a structure when subjected to lateral loads or unsymmetrical vertical loads.
Simple or Single Span
A span with supports at each end, no intermediate support, that restrain only against vertical displacement with the ends of the member being free to rotate.
Single Curvature
When moments produce a deformed or bent shape of a structural member having a smooth continuous curve or arc.
Single Slope
A sloping roof in one plane which slopes from one wall to the opposite wall.
Single-Ply Roof
A type of roofing system using thermoplastic membranes which are seamed by either hot air or solvent welding of one sheet to the next or using thermoset membranes which are seamed with an adhesive.
SJI (Steel Joist Institute)
The institute is a non-profit organization of active joist manufacturers that maintains sound engineering practice throughout the joist industry. The institute coopera Wtes with business and government agencies to establish steel joist standards and does continuing research of their products to maintain the integrity of their products.
Skew
The condition when two entities come together at an angle which is not 90 degrees or perpendicular to each other.
Skylight
An opening or roof accessory in a roof or ceiling for admitting light. If it bears across a joist, the top chord angles may be unbraced for design considerations.
Slag
A non-metallic byproduct of the welding process forming a hard crust over the molten steel which should be chipped away for inspection of a weld.
Slender Element Section
A steel section whose width-thickness ratios of any compression element exceeds the values of a noncompact section.
Slenderness Ratio
The ratio of the effective length of a column to the radius of gyration of the column about the same axis of bending.
Slip-Critical Joint
A bolted joint in which the slip resistance of the connection is required.
Slope
The angle or inclination a structural member makes with reference to a horizontal position expressed in inches of vertical rise per 12 inches of horizontal run, i.e. 3/12.
Slot Length
The length of a slotted hole in a joist bearing seat or other structural connection.
Slot Weld
See Plug Weld.
Snow Drift
The triangular accumulation of snow at high/low areas of structures expressed in PSF or PLF.
Snow Load
Are forces applied to a member by snow accumulation on the roof of a structure.
Soffit
A panel which covers the underside of an overhang, cantilever end, or mansard.
Soil Pressure
The load per unit area that a structure exerts through its foundation on the underlying soil.
Span
The distance between supports which is the centerline of a beam, column, or joist girder or 4 inches onto a wall.
Spandrel Joist or Beam
A structural member at the outside wall of a building, supporting part of the floor or roof and possibly the wall above.
Special Design
A design required by a loading diagram or other special notes because a standard joist or joist girder cannot be specified from a load table.
Specification
The detailed description of requirements, materials, dimensions, etc. of a proposed building or project.
Specifying Professional
An architect or engineer, registered or licensed to practice professional architecture or engineering, as defined by the statutory requirements of the professional registration laws. See Building Designer.
Splice
The connection between two chord members or other structural members joined at their ends by welding or bolting to form a single, longer member.
Sprinkler System
A system for fire protection usually consisting of overhead piping connected to a water supply to which automatic sprinklers are attached that discharges water in a specific pattern for extinguishment or control of a fire.
Square
In deck terminology, it is the term for 100 square feet of deck or roofing surface.
Formula: number of squares = sum of(length of deck sheet in feet * width of deck sheet in feet * number of pieces)divided by 100.
Square Cut
A cut to a structural member made at 90 degrees to the length of the member.
SRI (Steel Recycling Institute)
Abbreviation.
SSPC (Steel Structures Painting Council)
A professional technical society whose primary objective is to improve the technology and practice of prolonging the life of steel and concrete structures through the use of protective coatings.
SSR (Standing Seam Roof)
A type of roof system where the deck is attached to clips which are then attached to the beam or joist. Usually this type of roof system cannot be counted on to provide lateral stability or support to the joist top chord.
SSRC (Structural Stability Research Council)
Abbreviation.
ST
A hot rolled structural tee shape with symbol ST which is cut or split from S Shapes.
Stability
The property of a body to maintain its shape and remain rigid when detached from its support. Also see Rigid Frame or Structure.
Stabilizer Plate
A steel plate at a column or wall inserted between the end of a bottom chord of a joist or joist girder to weld the bottom chord to or to restrain the bottom chord from lateral movement.
Starter Joist
A joist which is spaced close to a wall for deck support, usually 6 inches.
Static Equilibrium
A member or body that is initally at rest and remains at rest when acted upon by a system of forces.
Static Load
A load applied slowly and then remains nearly constant.
Statically Determinate
A member or structure that can be analyzed and the reactions and forces determined from the equations of equilibrium.
Statically Indeterminate
A member or structure that cannot be analyzed soley by the equations of statics. It contains unknowns in excess of the number of equilibrium equations available. Additional equations must be written based on a knowledge of elastic deformations.
Stiffener
A member used to strengthen another member against buckling or to distribute load or to transfer shear. Usually a flat bar, plate, or angle welded perpendicular to the longitudinal axis of the member.
Stiffness
The resistance to deformation of a structural member which can be measured by the ratio of the applied force to the corresponding displacement.
Story
That portion of a building which is between the upper surface of any floor and the upper surface of the floor next above.
Story Drift
The difference in horizontal deflection at the top and bottom of a story.
Strain Hardening
The condition when ductile steel exhibits the capacity to resist additional load than that which caused initial yielding after undergoing deformation at or just above the yield point.
Stress
An internal force that resists a load. It is the intensity of force per unit of area, i.e., psi (pounds per square inch).
Stress Concentration
A localized stress which is considerably higher than average due to sudden changes in loading or sudden changes in geometry.
Stringer
In buildings, a structural member supporting stair steps.
Strong Axis
The cross section which has the major principal axis.
Structure
A mechanism designed and built or constructed of various parts jointed together in some definite manner to carry loads and resist forces.
Structural Steels
A large number of steels that are suitable for load-carrying members in a variety of structures because of strength, economy, ductility, and other properties. Strength levels are obtained by varying the chemical composition and by heat treatment.
Strut
A structural member used as a brace to resist axial forces.
Stud
A wood or metal vertical wall member to which exterior or interior covering material may be attached. It can be either load bearing or non-load bearing.
Suction
A partial vacuum due to wind loads on a building which cause a load in the outward direction.
Sump Pan
A metal deck accessory used at drain locations to close the opening where holes are cut in the metal deck.
Superimposed Load
Usually means a load that is in addition to the dead weight of the bar joists and bridging.
Sweep
The curvature of a structural member in the perpendicular transverse direction of its vertical axis.

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[T]

Tagged End (T.E.)
This is the end of a joist or joist girder where an identification or piece mark is shown by a metal tag. The member must be erected with this tagged end in the same position as the tagged end noted on the erection plan.
Tangent Modulus
The slope of the stress-strain curve of a material in the inelastic range at any given stress level.
Tee
A hot rolled shape with symbol T and is shaped like a "T".
Tempory Structure
Anything which is built which will not become part of the permanent structural system and will eventually be removed before or after the completion of the structure.
Tensile Strength
The longitudinal pulling stress a material can withstand without tearing apart or the maximum tensile stress the material can sustain.
Tension
A condition caused by the action of stretching or pulling of a component.
Tensile Strength
Or ultimate strength, is the largest unit stress a material can achieve in a tensile test.
Thermal Block
A spacer which has a low thermal conductance.
Thrust
The horizontal component of a reaction or an outward horizontal force.
Tie
A rod, plate, or angle welded between a two angle web member or between a top or bottom chord panel to tie them together usually located at the middle of the member. See Filler or Plug.
Tie Joist
A joist that is bolted at a column.
Tilted Joist
A joist which is supported in a manner such that the vertical axes of the joist is not perpendicular with respect to the ground.
Toe
The outside points of each leg of a structural angle.
Toe of Fillet
1) The end or termination edge of a fillet weld 2)The end or termination edge of a rolled section fillet.
Toe of Weld
The junction between the face of a weld and the base metal.
Ton
A unit of weight equal to 2000 pounds.
Top Chord
The top member of a joist or joist girder.
Top Chord Bearing
The bearing condition of a joist or joist girder that bears on its top chord seat.
Top Chord Extension (TCX)
The extended part of a joist top chord only. This type has only the two top chord angles extended past the joist seat. See Overhang.
Torque Wrench
A wrench containing an adjustable mechanism for measuring and controlling the amount of turning force exerted when used to tighten nuts and bolts.
Torsion Loads
A load that causes a member to twist about its longitudinal axis. Simple torsion is produced by a couple or moment in a plane perpendicular to the axis.
TOS
Abbreviation for 'Top of Steel'.
Toughness
The ability of a steel to absorb large amounts of energy without being readily damaged.
Transverse
Crossing from side to side or placed crosswise.
Tribuitary Width or Area
The design area which contributes load to a structural member. It is one half the distance between members on either side of the member.
Trimmer Joist
One of the joists supporting a header. The header applies a concentrated load at that point on the trimmer joist.
Truss
In general, a structural load-carrying member with an open web system designed as a simple span with each member designed to carry a tension or compression force. The entire structure act will act like a beam.
Tube
A hollow structural steel member shaped like a square or rectangle used as a beam, column, or for bracing. Usually the nominal outside corner radius is equal to two times the wall thickness.
Turnbuckle
A rotating sleeve or link with internal screw threads at each end and used to tighten or connect the ends of a rod.
Turn-of-the-Nut-Method
A method for pre-tensioning high-strength bolts by the rotation of the wrench a predetermined amount after the nut has been tightened to a snug fit.

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[U]

UBC (Uniform Building Code)
A minimum model regulatory code for the protection of public health, safety, welfare and property by regulating and controlling the design, construction, quality of materials, use, occupancy, location and maintenance of all buildings and structures within a jurisdiction.
UL (Underwriters Laboratories, Inc.)
A non-profit product safety testing and certification organization.
Ultimate Load
The force necessary to cause rupture.
Ultimate Strength
The maximum stress attained by a structural member prior to rupture which is the ultimate load divided by the orginial cross-sectional area of the member.
Ultimate Strength Design
See LRFD.
Unbraced Frame
A frame providing resistance to lateral load by the bending resistance of the frame members and their connections.
Unbraced Length
The distance between points of bracing of a structural member, measured between the centers of gravity of the bracing members.
Unbraced Top Chord
The specific length where the top chord of a joist has no lateral bracing by deck, bridging, or any other means.
Undercut
A notch or groove melted into the base metal next to the toe or root of a weld and left unfilled by weld metal.
Underslung
Description of a joist which is suspended from upper support points where most of the mass of steel is below the actual support points.
Uniformly Distributed Load
A load or force, for practical purposes, that may be considered constant over the entire length or partial length of the member.
UNO
Abbrevation for 'Unless Noted Otherwise'.
Uplift
The wind load on a member which causes a load in the upward direction. The gross uplift is determined from various codes and is generally a horizontal wind pressure multiplied by a factor to establish the uplift pressure. The net uplift is the gross uplift minus the allowable portion of dead load including the weight of the joist and is the load that the specifying professional shall indicate to the joist manufacturer.
Uplift Bridging
The bridging required by uplift design. Usually always required at the first bottom chord panel point of a K-Series, LH- or DLH-Series joist and at other locations along the bottom chord as required by design.
Upstanding Leg
The leg of a structural angle which is projecting up from you when viewing.

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[V]

Valley
The angle formed by two sloping sides of a roof.
Value Engineering
The application of the Scientific Method to the study of selecting the optimum or best system that meets the need of the customer.
Vapor Barrier
A physical membrane which prevents moisture or water vapor from penetrating to the other side.
Varying Distributed Load
A load or force, for practical purposes, that may be considered varying over the surface of the member, for example a snow drift.
VG-Type Joist Girder
A type of Joist Girder where joists are located at panel points where vertical webs intersect the top chord only. This type of girder is used for ducts to pass thru since the joists do not interfere with their passage.
Vibration
The oscillating, reciprocating, or other periodic motion of a rigid or elastic body or medium such as a floor when its position or state of equilibrium has been changed.

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[W]

W Shapes
A hot rolled shape called a Wide Flange Shape with symbol W which has essentially parallel flange surfaces.
Wall
A vertical or near vertical structure which encloses or separates spaces and may be used to resist horizontal or vertical forces or bending forces.
Wall Anchor
A small piece of angle or other structural material that is usually bolted to a wall to which a starter joist or bridging angle is welded or bolted to.
Wall Covering
The exterior wall skin consisting of sheets or panels.
Washer
A flat ring of metal with a hole in the middle used to give thickness to a joint or to distribute pressure under the head of a nut or bolt.
Weak Axis
The cross section which has the minor principal axis.
Weathering Steel
A type of high-strength steel which can be used in normal outdoor environments without being painted. Should not be used in corrosive or marine environments.
Web
1) The vertical or diagonal members joined at the top and bottom chords of a joist or joist girder to form triangular patterns or 2) The portion of a structural member between the flanges.
Web Buckling
The buckling of a web plate.
Web Configuration
The arrangement of the actual web system of a joist or joist girder which can be shown with a profile view of the member.
Web Crippling
The local failure of a web plate in the region of a concentrated load or reaction.
Welded Splice
A splice between two materials which has the joint made continuous by the process of welding.
Welding
The process of joining materials together, usually by heating the materials to a suitable temperature.
Weldability
Is the ability of a steel to be welded without its basic mechanical properties being changed.
Welding Washer
A metal device with a hole through it to allow for plug welding of deck to structural steel.
Wind Column
A vertical member supporting a wall system designed to withstand horizontal wind loads. Usually between two main vertial load carrying columns.
Wind Load
A force or lateral pressure in pounds per square foot that is applied to a member due to wind blowing in any direction.
Windward
The direction or side toward the wind. Opposite of leeward.
Working Drawings
The complete set of architectural drawings prepared by a registered architect.
Working Load
Also called service load, is the actual load that is acting on the structure.
Working Point
The point where two or more centroid lines of structural members intersect.
WRC (Welding Research Council)
This organization conducts cooperative research in welding with interested scientific societies, government departments, and any company using welded products.
WSD (Working Stress Design)
A structural design method whereby a structural element is designed so that the unit stresses computed under the action of working or service loads do not exceed the specified allowable values. See Allowable Stress Design and Elastic Design.
WT
A hot rolled structural tee shape with symbol WT which is cut or split from W Shapes.

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[X]

X-Brace
Structural bracing which resembles the letter "X".

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[Y]

Yield Point (Fy)
Is that unit stress at which the stress-strain curve exhibits a definite increase in strain without an increase in stress which is less than the maximum attainable stress.
Young's Modulus
See Modulus of Elasticity.

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[Z]

"Z" Section
A structural section in the shape of a "Z" cold formed from a steel sheet.

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