File:The elastic properties of concrete under bi-axial loading (1912) (14781358042).jpg

Identifier: elasticpropertie00mill (find matches)
Title: The elastic properties of concrete under bi-axial loading
Year: 1912 (1910s)
Authors: Millard, Floyd Hays
Subjects: Concrete Theses
Publisher:
Contributing Library: University of Illinois Urbana-Champaign
Digitizing Sponsor: University of Illinois Urbana-Champaign

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ote the unit stress, e denote unit deformation, E modulus of elasticity, r Poissons ratio e = r/s = deformation parallel to line of action ofstress. This is reduced by re z: rf/fe \7hich is produced bythe stress perpendicular to the first (assui-ned to be equal tothe other stress). The total deformation is then e = e - re« =^(1 - r) (1). The experiments shoir that (1 - r) is 0.78 for crossed beams and0.80 for compressions. Let t/E be unity in (1) and TTTite 0.80for (1 - r). It then appears that when the deformation causedby bi-axial loading is 0.30 of that caused by simple loadiiis,the value of r is 0.20, or about tvice what we should expectfrom the results of tests on columns. It seems that the value of Poissons ratio as determined fromtests of columns does not apply to bending action. Poissonsratio is greater than the value found from column tests. Inorder to explain the reduction of deformation by the usual methodof computation, a value of Poissons ratio of about 0.2 Liustbe used.
Text Appearing After Image:
145 21. Conroarisor: of Hosults of Crossed Besinj and CoiToreLj^ionSpecimens Loaded Equally on the Two Arms.-a number of comparisonsbet^reen results obtained from crossed beams and compressionspecimens loaded equally on the two arms have been dravm in thediscussion of stress-deformation relations. Tliese v/ill bebriefly summarized here. It will be remembered that a cross-section of an arm Is asquare and that the cross Is a cube In both cases. We shouldexpect quite similar results from the tv/o series, since compres-sive deformations ■••ere measured on the surface of the specimen.The deformation on the cross of a compression specimen nas foundto be 0.66 of the deformation oii the arm and the deformation onthe cross of a beam was found to be 0.67 of the deformation onthe arm. The amount of compression carried by the enlargement ofsection as found from the curves showing the distribution ofdeformation was 0.145 of the whole on the crossed beams atthe highest load and was between 0.

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