Open web steel joist
Encyclopedia
In structural engineering
, the Open Web Steel Joist
(OWSJ) is a lightweight steel
truss
consisting, in the standard form, of parallel chords and a triangulated web system, proportioned to span between bearing points.
The main function of an OWSJ is to provide direct support for roof or floor deck and to transfer the load imposed on the deck to the structural frame i.e. beam
and column
.
In order to accurately design an OWSJ, engineers consider the joist span between bearing points, joist spacing, slope, live loads, dead loads, collateral loads, wind uplift, deflection
criteria and maximum joist depth allowed. Many steel joist manufacturers supply load tables in order to allow designers to select the most efficient joist sizes for their projects.
While OWSJs can be adapted to suit a wide variety of architectural applications, the greatest economy will be realized when utilizing standard details, which may vary from one joist manufacturer to another. Some other shapes, in addition to the parallel top and bottom chord, are single slope, double slope, curved, gable and scissor configurations. These shapes may not be available from all joist manufactures, and are usually supplied at a premium cost that reflects the complexity required.
Structural engineering
Structural engineering is a field of engineering dealing with the analysis and design of structures that support or resist loads. Structural engineering is usually considered a specialty within civil engineering, but it can also be studied in its own right....
, the Open Web Steel Joist
Joist
A joist, in architecture and engineering, is one of the horizontal supporting members that run from wall to wall, wall to beam, or beam to beam to support a ceiling, roof, or floor. It may be made of wood, steel, or concrete. Typically, a beam is bigger than, and is thus distinguished from, a joist...
(OWSJ) is a lightweight steel
Steel
Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...
truss
Truss
In architecture and structural engineering, a truss is a structure comprising one or more triangular units constructed with straight members whose ends are connected at joints referred to as nodes. External forces and reactions to those forces are considered to act only at the nodes and result in...
consisting, in the standard form, of parallel chords and a triangulated web system, proportioned to span between bearing points.
The main function of an OWSJ is to provide direct support for roof or floor deck and to transfer the load imposed on the deck to the structural frame i.e. beam
Beam (structure)
A beam is a horizontal structural element that is capable of withstanding load primarily by resisting bending. The bending force induced into the material of the beam as a result of the external loads, own weight, span and external reactions to these loads is called a bending moment.- Overview...
and column
Column
A column or pillar in architecture and structural engineering is a vertical structural element that transmits, through compression, the weight of the structure above to other structural elements below. For the purpose of wind or earthquake engineering, columns may be designed to resist lateral forces...
.
In order to accurately design an OWSJ, engineers consider the joist span between bearing points, joist spacing, slope, live loads, dead loads, collateral loads, wind uplift, deflection
Deflection (engineering)
In engineering, deflection is the degree to which a structural element is displaced under a load. It may refer to an angle or a distance.The deflection distance of a member under a load is directly related to the slope of the deflected shape of the member under that load and can be calculated by...
criteria and maximum joist depth allowed. Many steel joist manufacturers supply load tables in order to allow designers to select the most efficient joist sizes for their projects.
While OWSJs can be adapted to suit a wide variety of architectural applications, the greatest economy will be realized when utilizing standard details, which may vary from one joist manufacturer to another. Some other shapes, in addition to the parallel top and bottom chord, are single slope, double slope, curved, gable and scissor configurations. These shapes may not be available from all joist manufactures, and are usually supplied at a premium cost that reflects the complexity required.