Modified Rectangular Stress Block for High Strength RC Columns to Axial Loads with Bidirectional Eccentricities

Title & Authors
Modified Rectangular Stress Block for High Strength RC Columns to Axial Loads with Bidirectional Eccentricities
Yoo, Suk-Hyeong; Bahn, Byong-Youl; Shin, Sung-Woo;

Abstract
In the previous experimental study, it is verified that the ultimate strain of concrete ($\small{\varepsilon}$$\small{_{cu}}$ =0.003) and coefficient of equivalent stress block ($\small{\beta}$$\small{_1}$) can be used for the analysis of RC beams under biaxial and uniaxial bending moment. However, the characteristics of stress distribution of non rectangular compressed area in the RC columns are different to those of rectangular compressed area. The properties of compressive stress distribution of concrete have minor effect on the pure bending moment such as beams, but for the columns subjected to combined axial load and biaxial bending moment, the properties of compressive stress distribution are influencing factors. Nevertheless, in ACI 318-99 code, the design tables for columns subjected to axial loads with bidirectional eccentricities are based on the parameters recommended for rectangular stress block(RSB) of rectangular compressed areas. In this study the characteristics of stress distribution through both angle and depth of neutral axis are observed and formulated rationally. And the modified parameters of rectangular stress block(MRSB) for non rectangular compressed area is proposed. And the computer program using MRSB for the biaxial bending analysis of RC columns is developed and the results of MRSB are compared to RSB and experimental results respectively.
Keywords
biaxial bending;ultimate strain;equivalent stress block;plastic analysis;
Language
Korean
Cited by
References
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