Pudjisuryadi, Pamuda (2011) TRANSVERSE STRESS DISTRIBUTION IN CONCRETE COLUMNS EXTERNALLY CONFINED BY STEEL ANGLE COLLARS. In: The 2nd International Conference on Earthquake Engineering and Disaster Mitigation, 19-07-2011 - 20-07-2011, Surabaya - Indonesia.
Abstract
Transverse confining stress in concrete columns has been known to enhance the strength and ductility. Recently, external confinement techniques have been widely developed due to the high demand of columns retrofits. For square or rectangular columns, providing effective confining stress by external retrofit is not an easy task. The stress concentration at corners causes highly non-uniform confining stress distribution. One approach of external retrofit for rectangular concrete column is by using steel collars. Simple collars consist of steel angles connected by bolts in their corners can be a promising retrofit method. In this study, the proposed retrofit method is simulated by Finite Element approach using the ABAQUS software. Steel Collars consisting of four steel angles installed with uniform spacing are used to confine the columns externally. The model is subjected to uniform unit compressive pressure on top, and restraint by vertical rollers on the bottom. An important assumption is made by making perfect bond between concrete column and the steel collars. The connections at four corners of each collar are also assumed to be perfect. The main objective of the study is to observe if 3D Finite Element modeling by using ABAQUS can simulate the confining effect of the steel collars. Results show that the steel collars suffer both axial and bending action in order to confine the concrete lateral expansion. Consequently, the concrete experiences transverse stress distributions from the confinement effect. However, relatively uniform transverse stress distribution due to strong contact between concrete and steel collars may not be achieved easily in actual practice. But the results indicate that if the steel collars are strong enough, more uniform transverse stress distribution can be expected. In conclusion, the Finite Element modeling by ABAQUS software in this study, can predict the behavior of the idealized retrofit approach.
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