When a major tornado happens, it is all over the news. And, every year, the average person may recall hearing about a dozen or so tornado events, if that. So it might be startling to know that, on average, the number of tornadoes that touch down each year in the United States, according to www.ustornadoes.com, is more than 1,200. …
Author Archives : Roger LaBoube, Ph.D, P.E.
Roger LaBoube is Curator’s Distinguished Teaching Professor of Civil Engineering and Director of the Wei-Wen Yu Center for Cold-Formed Steel Structures at the Missouri University of Science and Technology. Roger is active in the American Iron and Steel Institute’s Committee on Framing Standards and the Committee on Specifications. He also served on STRUCTURE’s Editorial Board. (laboube@mst.edu)
The design provisions for the shear strength of steel-to-steel screw connections provided by Section E4.3 of the North American Specification for the Design of Cold-Formed Steel Structural Members, AISI S100-12, are based on testing. …
When damaged members and connections are identified, it is imperative to assess the extent that the damage may impact the structural integrity of the cold-formed steel member or connection. As stated in the Engineers Notebook article, Evaluation of Cold-Formed Steel Members and Connections (STRUCTURE, February 2018), assessment should be made quickly to contain the damages or protect the public welfare. …
When damaged cold-formed steel members or connections are identified, it is imperative they are assessed to determine the extent of the compromise to the structural integrity and the load carrying ability. Often, such assessment has to be made quickly to contain the propagation of damage to adjacent members and to protect the public welfare. Replacement of material is always an option. However, it may not be the most economical or expeditious solution. …
Updated for 2018 IBC
From 2001 to 2012, the AISI Committee on Framing Standards developed nine different framing standards to cover specific aspects of cold-formed steel framing. Six of these standards addressed the design of structural elements, such as general provisions, wall studs, floor joists, trusses, headers, and shear walls. …
In cold-formed steel construction, welding is a viable connection method. Prefabrication of trusses, panelization of walls, and hardware components are all ideal applications where welding may be the preferred joining method. …
A box beam configuration may be used at openings in a floor or wall framing assembly. The American Iron and Steel Institute’s AISI S100 contains design provisions for built-up flexural members consisting of two C-sections oriented back-to-back to form an I-shaped section, i.e. Section D1.1, but does not contain design guidance for a box-section formed by orienting two C-sections lip-to-lip. …
Built-up cold-formed steel compression members are commonly used as shear wall chord members, and at openings of doors and windows (stud packs) to resist the additional load transferred from an opening header. The provisions in North American Specification for the Design of Cold-Formed Steel Structural Members, AISI S100 Section D1.2 are limited to concentrically loaded compression members composed of two shapes joined together at discrete points along the axis of the member. Thus, the AISI S100 provisions are limited to either an I-shaped cross section or a box-shaped cross section. …
Most typical nonstructural partitions are specified and constructed in accordance with the industry or manufacturers’ design tables and would not require additional, formal engineering input on a project-by-project basis. The manufacturers’ design tables are based on engineering principles and tests. However, there are projects where the requirements are outside the limits of the manufacturers’ design tables. …