JOISTS
STANDARD JOISTS
SPECIAL PROFILE JOISTS
Joist products are designed and manufactured in accordance with the specifications of the Steel Joist Institute.
Standard Joist
All standard profile joists are available with either under-slung or square ends. LH-Series and DL H-Series joists are available with single pitched or double pitched top chords. The depth indicated in joist designation is determined by the depth of single pitched joists at the center of span and at ridge centerline of double pitched joists. When top chord slope exceeds 1/8":12", total and live top chord uniform loads must be provided. All standard profile joists will be furnished with standard SJI camber as indicate d in SJI Table 1 03.6-1, unless specified otherwise in contract documents.
Standard steel joist |
Parallel Chord |
Single Pitched Top Chord |
Double Pitched Top Chord |
Special Profile Joists
New Millennium Building Systems (NMBS) has plants located in South Carolina and Ohio that have been specifically designed and equipped to produce special profile joists. This allows us to maintain consistent quality and provide cost advantages through not having to compromise manufacturing processes to accommodate special profiles. Experienced NMBS design personnel equipped with specially developed software are on staff. Additionally, NMBS manufacturing personnel and shipping personnel are experienced in all such products. Flexible to the Finish of the project, the entire New Millennium team is readily available to aid the owner’s representatives in a timely completion of special projects.
Special profile joists are available with either under-slung or square ends. Due to the limitations of depth and span that are inherent in special profiles, it is recommended that the owner’s representative contact NMBS early in the design stage. (Visit the Contact page on this website for individual plant contact information.) Depth limitations depend on plant-specific manufacturing, painting, and shipping issues. The shipping issues vary from project to project due to site specific parameters and state trucking regulations. Considerable cost savings may be found by addressing these issues early in the design process. Many of these special profile joists require field splicing (horizontal or vertical), involving installation cost at the jobsite. To have a fair and accurate process, these issues are best identified and resolved prior to bid.
Design and Manufacture
All NMBS special profile joist members are designed and manufactured to, and use materials that conform to, the specifications of the Steel Joist Institute (SJI).
Scissors and Arch or Barrel joists present a horizontal thrust to the supporting structure. The specifying professional needs to give consideration to this thrust and the resulting lateral displacement in the design of the supporting structure. NMBS engineers are readily available for consultation. Just as with any other special requirements, load and deflection requirements for these products need to be clearly specified on the contract drawings.
All special profile joists are furnished with no camber unless otherwise specified on the contract documents.
Design calculations prepared by a Professional Engineer registered in the state of manufacture are available for NMBS special profile joists.
Application
Refer to the SJI Specification for LH- and DLH-Series for general rules guiding the use of these special profile joists.
All bridging is to be bolted diagonal.
Erection Stability and Handling
Refer to the SJI Specification for LH- and DLH-Series for minimum rules guiding the erection of these special profile joists.
Due to the fact that more degree of instability may be present in high center of gravity joists (even with no load other than self weight), such as all of the special profile steel joists, the specifying professional and erector are advised to be very conservative in determining the type and amount of bridging and bridging anchorage.
At a minimum, the specifying professional and erector should be certain that before any load is allowed on the special profile joists:
1) All rows of bridging shall be bolted diagonal bridging.
2) Hoisting cables shall not be released until all rows of bridging are installed and anchored and both ends of the joist are attached to its support.
The following special profile products can be furnished by New Millennium
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