Alternative Title

Civil Engineering Study 96-1

Abstract

PREFACE To aid in adapting cold-formed steel to the residential market, a research project was initiated in 1993 at the University of Missouri-Rolla. Design issues relating to the use of cold-formed steel members and connections in residential roof truss systems have been the focus of the project. The purpose of this research was to study the behavior of cold-formed steel roof truss systems and to establish appropriate design recommendations. Overall, the research findings were intended to aid the promotion of cold-formed steel as a safe, serviceable, and cost effective alternative in residential construction. The First Summary Report was issued in May 1995. The report outlined the research effort to date which included a review of available literature, followed by a comparative analysis of experimental truss behavior to a computer generated model. The experimental investigation involved an evaluation of the overall truss behavior using full-scale truss assemblies. Based on this information, a computer generated model was created to simulate the truss assembly. An evaluation of deflection and stress data was used to correlate the computer model to the full-scale truss. The computer model and AISI Specification formed the basis used to establish the predicted failure load, which was then compared to the tested failure of the full-scale truss assembly. The conclusions obtained from the experimental investigation were used to formulate design recommendations. This second summary report focuses on the behavior of the web members of a cold-formed steel truss assembly. Twenty-eight full-scale tests were completed in this phase of the study. The truss assemblies were fabricated using C-sections with top chords continuous from heel-to-ridge, bottom chord continuous from heel-to-heel, and web members connecting between the chords. All connections were made using 3/4 in. long, No. 10, self-drilling screws. The pitch of the top chord was maintained at 4:12 for all truss assemblies. The compression web members had thicknesses from 0.0360 to 0.0593 in. Web members had slenderness ratios that varied from 100 to 180. The data recorded consisted of measurements of transverse deflections at the midspan of the compression web member, strain measurements at the same location, and the end reactions at the truss supports. Recommendations are made for the modeling of truss assemblies and the design of compression web members. This report is based on the thesis presented to the Faculty of the Graduate School of the University of Missouri-Rolla in partial fulfillment of the requirements for the degree of Masters of Science in Civil Engineering. This material is based upon work supported by the National Science Foundation under Grant No. MSS-9222022 and by the American Iron and Steel Institute. The technical guidance provided by the Technological Research Subcommittee of the AISI Residential Advisory Committee is gratefully acknowledged. Thanks are also extended to A. Ziolkowski and R. B. Haws, AISI staff, and J. B. Scalzi of the National Science Foundation. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not reflect the views of the National Science Foundation.

Department(s)

Civil, Architectural and Environmental Engineering

Research Center/Laboratory(s)

Wei-Wen Yu Center for Cold-Formed Steel Structures

Sponsor(s)

American Iron and Steel Institute
National Science Foundation (U.S.)

Appears In

Cold-Formed Steel Series

Publisher

Missouri University of Science and Technology

Publication Date

8-1-1996

Document Version

Final Version

Rights

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

Comments

Second Summary Report

Document Type

Report - Technical

File Type

text

Language

English


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