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A study of stability of axially compressed plates reinforced by edge angles

Authors
Publisher
Purdue University
Publication Date
Keywords
  • Engineering
  • Mechanical
Disciplines
  • Design

Abstract

The purpose of this research was to determine the relative proportions of the flange angles necessary to make an axially compressed plate reach any buckling strength up to 60,000 psi. ^ The principal variables which were investigated were the L/b ratio for the plate, the b/t ratio for the plate, and the size of edge angles. Steel of various yield points was used, with the maximum being about 75,000 psi. The range of the variables was so chosen as to cover the current practice and extend considerably above the values now being generally used. ^ Eighty column specimens have been tested under axial compression with lateral support so arranged as to simulate the effect of lacing bars as used in column design. The specimens were built up channels each consisting of a web plate with edge angles on one face. The test columns are arranged in fifteen series such that the only variable for a given series is the size of edge angles used. ^ SR-4 strain gages were used to determine the stress distribution throughout the member and to measure the stresses during buckling. Mechanical dial indicators were used to determine the overall change in length of the specimen and the lateral deflections due to the axial loading. ^ Lateral support for the specimens was provided at the third points along each edge of the plate. ^ Principal results and conclusions are as follows: (1) It is possible to stiffen plates with edge angles so that they will carry the stress given by the Bryan formula for an axially compressed plate with simple supports along the longitudinal edges. (2) Present methods of analysis do check the experimental results. (3) With proper care the current limit of b/t for web plates may be considerably exceeded. Edge angles of sufficient size must be used. (4) A set of tentative ultimate strength curves are given showing the size of edge angles required to make a plate of given b/t safe against buckling for any stress up to 60,000 psi. This curve applies to plates where the L/b ratio is 2. ^

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