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HancockJoist - Structural Glossary Category: Architecture and Buildings > JOIST AND STRUCTURAL GLOSSARY Date & country: 12/09/2008, USA Words: 598

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.

Primary Members
This is the main load carrying members of a structure such as a beam or joist girder.

Press Brake
A machine used in cold-forming metal sheet or strip into a desired cross section or structural shape.

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.

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.

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.

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.

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.

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.

PLF (Pounds per Linear Foot)
A unit of load obtained by multiplying pounds per square foot times the tribituary width on a joist.

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.

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.

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.

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,

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.

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...

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.

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.

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.

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).

Partially Restrained
A type of connection that displays a moment rotation behavior that can neither be described as pinned nor fixed.

Part Number
See Mark and Piece Mark.

Parapet
The portion of a vertical wall of a building which extends above the roof line at the intersection of the wall and roof.

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.

Panel Point
The point where one or more web members intersect the top or bottom chords of a joist or joist girder. See Joint.

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.

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. [] [P]

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.

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.

NTS
Abbreviation for 'Not to Scale'. [] [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.

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.

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.

Newton
The SI unit of measure for force (N).

NIC
Abbreviation for 'Not in Contract'.

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.

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.

NBS (National Bureau of Standards)
Abbreviation.

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.

Mylar
A type of strong, thin polyester sheet used for producing blueprints of architectural drawings. [] [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.

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.

MPC (Materials Properties Council)
Abbreviation.

Monorail
Usually a single rail support for a material handling system.

Moment Plate
A welded steel plate used to develop a rigid connection to the supporting member so that moment transfer can occur.

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
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.

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.

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.

Milli
SI prefix for 10^-3 or 0.001

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.

Milled
A surface which has been accurately sawed or finised to a true plane.

Mil
A measurement of thickness of paint. One mil=.001 of an inch.

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.

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.

Metal Stud
A structural steel member used for framing walls just as a regular wooden one.

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.

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.

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.

MC Shapes
A hot rolled shape called a Miscellaneous Channel with symbol MC.

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.

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.

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.

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.

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.

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.

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.

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.

Load Combination
The combination of loads which produce the worse loading condition in a structural member.

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.

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.

Lintel
A horizontal structural member spanning a door, window, or other wall opening which supports a wall or any construction immediately above.

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.