| Summary: | 碩士 === 中正理工學院 === 軍事工程研究所 === 87 === Nine solid cylinders using normal-strength concrete were tested under torsional loading to determine torsional strength and twist angles, and to study their mechanical behaviors and failure appearances. The major va-riable was the cross section, keeping the length constant, three different cross-sectional diameters, 150mm, 125mm and 100mm, were designated as Types A, B and C respectively. Three specimens were tested for each type.
On the basis of the results obtained in this study, it is showed that the cracked torsional strength and the twist angles of the specimens are affected by the cross-sectional dimensions. The bigger the dimensions of the specimens, the higher the cracked torsional strength and the twist angle. When the cracked torsional strength reaches, all of the tested strain values are about within the scope of the ultimate tensile strain, and the equivalent values of principle stresses are larger than the splitting tensile strength. When the specimen fails, the failure surface is a typical rough and curved surface. The experimental values of cracked torsional strength are larger than the average of the predicted values from the elastic theory and than those from the plastic theory with errors of 49﹪and 12﹪respectively, but with errors less than 1﹪in comparison with those predicted from the skew-bending theory.
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