Alternative Title

Civil Engineering Study 91-4

Abstract

INTRODUCTION It has long been recognized that material properties and stress-strain relationships of sheet steels can be influenced by the strain rate. A considerable amount of theoretical and experimental research have been undertaken in the past to study material properties and the behavior of structures under dynamic loads and impact loads. In view of the fact that in the current AISI Automotive Steel Design Manual 1, the design criteria for effective design width are based on the test results under static loading condition, the objective of this investigation was to study the validity of these effective design width formulas for the design of cold-formed steel structural members subjected to dynamic loads. In order to investigate the structural behavior and strength of cold-formed steel members under dynamic loads, the material properties of three selected sheet steels (35XF, 50XF, and 100XF) have been studied at the University of Missouri-Rolla. The test results of the static and dynamic mechanical properties in tension and compression under different strain rates were established in the first phase of the project. The nominal yield strengths of these three types of sheet steels ranged from 35 to 100 ksi and the range of strain rates varied from 10-4 to 1.0 in./in./sec .. Details of the tension and compression coupon tests were presented in the Eleventh and Twelfth Propress Reports 2,3. In Phase II of the project, the structural behavior and strength of cold-formed steel members having both unstiffened and stiffened elements were studied experimentally and analytically for stub columns and beams subjected to dynamic loads. Two materials (35XF and 50XF) were used in this phase of study. The test results of 97 stub columns with evaluation were summarized in the Fifteenth Progress Report 6. During the period from August 1989 through April 1990, fifteen (15) beam specimens using channel sections and fifteen (15) beam specimens using hat sections were tested to study the strength of structural members having unstiffened and stiffened compression elements, respectively. These test specimens were fabricated from 35XF sheet steel. The strain rates ranged from 10-5 to 10-2 in./in./sec .. The test results were presented in the Thirteenth and Fourteenth Propress Reports 4, 5. The study of beam specimens fabricated from 50XF sheet steel subjected to dynamic loads was initiated in March 1991. Fifteen (15) beam specimens using channel sections and fifteen (15) beam specimens using hat sections were tested for the purpose of studying the behavior of unstiffened and stiffened compression elements, respectively. The strain rates for these beam tests varied from 10-5 to 10-2 in./in./sec. In Chapter II, the experimental investigation of beam specimens is discussed in detail. The test data of beam specimens fabricated from two types of sheet steels (35XF and 50XF) are evaluated in Chapter III. Finally, the results of beam tests are summrized in Chaper IV.

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

Cold-Formed Steel Series

Publisher

Missouri University of Science and Technology (formerly the University of Missouri--Rolla)

Publication Date

9-1-1991

Document Version

Final Version

Rights

© Missouri University of Science and Technology (formerly the University of Missouri--Rolla)

Comments

Sixteenth Progress Report

Document Type

Report - Technical

File Type

text

Language

English


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