![]() All webs are designed for a vertical shear equal to the specified shear capacity and interior webs will be designed for 100% stress reversal. The moment capacity is constant at all interior panels. KCS joist chords are designed for a flat positive moment envelope. KCS (K-Series Constant Shear) joists are designed in accordance with the Standard Specification for K-Series Joists. KCS Joists Ĭommon steel joist chord and web configurations. When conditions such as this arise, a KCS joist may be a good option. When non-uniform and/or concentrated loads are encountered the shear and moment diagrams required may be shaped quite differently and may not be covered by the shear and moment design envelopes of a standard K-Series Joist. Standard K-Series Joists are designed for simple span uniform loading which results in a parabolic moment diagram for chord forces and a linearly sloped shear diagram for web forces. Seat depths deeper than 2 + 1⁄ 2 inches (64 mm) can also be specified. Standard K-Series Joists have a 2 + 1⁄ 2 inches (64 mm) end bearing depth so that, regardless of the overall joist depths, the tops of the joists lie in the same plane. ![]() There are 63 separate designations in the Load Tables, representing joist depths from 10 inches (250 mm) through 30 inches (760 mm) in 2 inches (51 mm) increments and spans through 60 feet (18,000 mm). ![]() K-Series Joists are standardized regarding depths, spans, and load-carrying capacities. They possess multiple advantages and features which have resulted in their wide use and acceptance throughout the United States and other countries. Open Web Steel Joists, K-Series, were primarily developed to provide structural support for floors and roofs of buildings. The joists covered by these early standards were later identified as open web steel joists, SJ-Series. Members of the industry began to organize the institute, and in 1928 the first standard specifications were adopted, followed in 1929 by the first load table. Architects, engineers and builders found it difficult to compare rated capacities and to use fully the economies of steel joist construction. Various other types were developed, but problems also followed because each manufacturer had their own design and fabrication standards. The first joist in 1923 was a Warren truss type, with top and bottom chords of round bars and a web formed from a single continuous bent bar. Load tables are available in both Allowable Stress Design (ASD) and Load and Resistance Factor Design (LRFD). Load tables and specifications are published by the SJI in five categories: K-Series, LH-Series, DLH-Series, CJ-Series, and Joist Girders. Continuing research and updating are included in this work. As a non-profit organization of active manufacturers, the Institute cooperates with governmental and business agencies to establish steel joist standards. The SJI has worked since 1928 to maintain sound engineering practice throughout the industry. The manufacture of OWSJ in North America is overseen by the Steel Joist Institute (SJI). These shapes may not be available from all joist manufacturers, and are usually supplied at a premium cost that reflects the complexity required. Some other shapes, in addition to the parallel top and bottom chord, are single slope, double slope, arch, gable and scissor configurations. 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. Many steel joist manufacturers supply economical load tables in order to allow designers to select the most efficient joist sizes for their projects. In order to accurately design an OWSJ, engineers consider the joist span between bearing points, joist spacing, slope, live loads, dead loads, collateral loads, seismic loads, wind uplift, deflection criteria and maximum joist depth allowed. 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. 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. Steel joists and Joist Girders being erected.
0 Comments
Leave a Reply. |