Alternative Title

Civil Engineering Study 90-3

Abstract

INTRODUCTION During recent years, more economic and lighter vehicles have been produced by automotive manufacturers because of the high cost of fuel. High strength sheet steels have been favorably used to accomplish the construction of such automobiles. One source of the design information for using sheet steels is provided in the AISI Automotive Steel Design Manual 1. In view of the fact that material properties and stress-strain relationships of sheet steels can be influenced by the strain rate, the material properties of three different sheet steels (35XF, 50XF, and 100XF) have been studied at University of Missouri-Rolla. This study involved primarily with the experimental determination of the mechanical properties in tension and compression under different strain rates from 10- 4 to 1.0 in./in./sec. The yield strengths of three types of sheet steels ranged from 35 to 100 ksi. The test results obtained from this study were presented in the Eleventh 2 and Twelfth 3 Progress Reports. Subsequently, the same results were used to evaluate the member strengths of stub columns and flexural members. During the period from August 1989 through April 1990, the structural behavior and strength of steel members having both unstiffened and stiffened elements were studied experimentally for stub columns and beams fabricated from 3SXF sheet steel. The test results were presented in the Thirteenth 4 and Fourteenth 5 Progress Reports. In the Thirteenth Progress Report, the w/t ratios for stub columns with the unstiffened elements ranged from 8.93 to 20.97 and the w/t ratios for stub columns with stiffened elements ranged from 26.92 to 53.39. The strain rates for stub column tests varied from 10-4 to 10- 1 in./in./sec. In order to study the behavior of cold-formed steel members with large w/t ratios, I-shaped sections having unstiffened elements with w/t ratios of about 44 and box-shaped sections having stiffened elements with w/t ratios of about 100 were fabricated from 35XF sheet steel and tested in August 1990. The test results and the evaluation are presented in Chapter II and Chapter III of this report, respectively. In addition, 48 stub columns have also been fabricated from 50XF sheet steel for static and dynamic tests. These specimens were tested during the period from August through October 1990. Because the current effective design width formulas were originally derived from the test results obtained from the static tests ,the main purpose of this study was to determine the validity of the current formulas for structural members subjected to dynamic loads. In Chapter II of this report, the experimental investigation of stub columns is discussed in detail. The test data are evaluated in Chapter III. In Chapter IV, the present and future research work are summarized and the conclusions are drawn on the basis of the available test results.

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

Appears In

Structural Series

Publisher

Missouri University of Science and Technology

Publication Date

11-1-1990

Document Version

Final Version

Rights

© 1990 Missouri University of Science and Technology, All rights reserved.

Comments

Fifteenth Progress Report

Document Type

Report - Technical

File Type

text

Language

English


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