CCFSS Library (1939 - present)

Alternative Title

Civil Engineering Study 96-3


INTRODUCTION A. GENERAL Conservation is becoming more prevalent in our society as it is a necessity to protect our environment and ensure our future. Recently, this growing environmental awareness has created concerns regarding the use of wood as an appropriate construction material. In addition, economic and safety concerns are pressuring the competitiveness of the wood industry. Timber prices have risen sharply as the result of a supply and demand crisis. Also, the recent devastation to wood structures by storms have led to the adoption of building codes which require engineered residential construction to minimize safety concerns. To improve the feasibility of residential construction, alternative building materials are being explored. One such alternate material is cold-formed steel. Due to its recyclability it is an environmentally attractive solution. In addition to satisfying environmental concerns, cold formed steel members have many other positive physical characteristics. They are mass produced with consistent dimensional properties, as well as being non-combustible, and insect and rodent resistant. Cold-formed steel has long been the preferred construction material for commercial light-industrial construction because it is cost competitive, possesses a high strength-to-weight ratio, and is simple and fast to erect. Since 1946 the use and the development of thin-walled cold-formed steel construction in the United States have been accelerated by the issuance of various editions of the "Specification for the Design of Cold-Formed steel Structural Members" of the American Iron and Steel Institute (AISI). Each subsequent edition incorporates investigation results which have improved the completeness and surety of the specification. For example, based on a study conducted by Hetrakul and Yu (1978), the 1980 edition underwent expansive refinement in the design of beam webs subjected to web crippling and the combination of bending and web crippling. However, the web crippling provisions and combined bending and web crippling provisions of the 1980 and subsequent revised editions of the specification pertain strictly to flexural members without web openings. Since 1990, the University of Missouri-Rolla has conducted a comprehensive study of the behavior of web elements of flexural members with web openings subjected to forces causing bending, shear, and web crippling, and combinations thereof. The current AISI ASD specification (1986) and AISI LRFD specification (1991a) have no provisions for the possible degradation in strength for the various limit states of flexural members caused by the presence of web openings. The use of members with pre-punched web openings spaced at intervals along the longitudinal axis of the section provides the convenience of providing passage for services without the considerable expense, delay, and need for quality control associated with web openings at the work site. Sections with web openings are frequently used in floors, ceilings, and walls to maximize occupancy volume by reducing the need for visible conduits. Cold-formed steel members with web openings are used extensively in practice and in relation to their cold-formed steel solid web counterparts, commonly comprise a majority of the cold-formed steel members used in light-steel construction. The foremost reason for conducting this investigation was the concern that the presence of web opening(s) would have a degrading effect on the web crippling behavior and the combined bending and web crippling behavior of flexural members. Therefore the effect of a web opening must be defined, and if necessary, recognized by the AISI specification provisions.


Civil, Architectural and Environmental Engineering


American Iron and Steel Institute

Research Center/Lab(s)

Wei-Wen Yu Center for Cold-Formed Steel Structures

Appears In

Cold-Formed Steel Series


Missouri University of Science and Technology

Publication Date

01 Aug 1996

Document Version

Final Version


© 1996 Missouri University of Science and Technology, All rights reserved.


Final Report

Document Type

Technical Report

File Type