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

Story Drift
The difference in horizontal deflection at the top and bottom of a story.

Stiffness
The resistance to deformation of a structural member which can be measured by the ratio of the applied force to the corresponding displacement.

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.

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.

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.

Static Equilibrium
A member or body that is initally at rest and remains at rest when acted upon by a system of forces.

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.

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.

SRI (Steel Recycling Institute)
Abbreviation.

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.

Square Cut
A cut to a structural member made at 90 degrees to the length of the member.

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.

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.

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.

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.

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.

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.

Soil Pressure
The load per unit area that a structure exerts through its foundation on the underlying soil.

Soffit
A panel which covers the underside of an overhang, cantilever end, or mansard.

Snow Load
Are forces applied to a member by snow accumulation on the roof of a structure.

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.

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.

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.

Slender Element Section
A steel section whose width-thickness ratios of any compression element exceeds the values of a noncompact section.

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.

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.

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.

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.

Single Slope
A sloping roof in one plane which slopes from one wall to the opposite wall.

Single Curvature
When moments produce a deformed or bent shape of a structural member having a smooth continuous curve or arc.

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.

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.

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 Lap Screws
A screw used to connect the sides of two adjacent sheets of deck together, #10 being the standard size.

Shore
The process of temporarily supporting a structure or structural member with auxiliary members.

Side Lap
The lap at the sides of a sheet of deck and is attached by side lap screws or welds between supports.

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.

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.

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.

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 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 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
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.

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.

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.

Sequence
A breakdown of when materials are to be made or delivered for a project with one following after the other.

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.

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.

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.

SDI (Steel Deck Institute)
An institute which brings uniformity to the design, manufacture, quality control, and construction practices applicable to cold-formed steel deck.

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.

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.

Scissor Joist
A non-standard type of joist where both the top chord and bottom chord are double pitched and parallel with each other.

Scab On
A member fastened or welded to another member for reinforcement.

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.

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.

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. [] [S]

Roof Overhang
A roof extension that projects beyond the ends or sides of a building.

Roof Covering
The exposed exterior roof skin of a building which can be sheets, panels or other materials.

Rod
A smooth solid round bar used for the web system of a bar joist.

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.

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.

Rigid Connection
A connection where moment is transfered from one member to another. See also Fixed-End Support.

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.

Retaining Wall
A wall designed to resist the lateral displacement of soil, water, or any other type of material.

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.

Repair
The reconstruction or renewal of any part of an existing structure or building for the purpose of its maintenance.

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.

Redundants
The reactions which are not necessary for static equilibrium.

Rake
The edge of a roof which intersects the gable part of a roof.

Reaction
The force or moment developed at the points of a support.

Rafter
The main beam supporting a roof system or a sloping roof framing member.

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.

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. [] [Q]

Puddle Weld
See Plug Weld.

PSF (Pounds per Square Foot)
A unit of stress which to multiply the tribituary width on a joist by to get PLF.

PSI (Pounds per Square Inch)
A unit of stress or pressure.

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.

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