Tests on stub columns of concrete-filled RHS sections

The behavior of stub columns of concrete-filled rectangular hollow sections (RHS) subjected to axial load was investigated experimentally. A total of 24 specimens were studied. The main parameters varied in the tests are: (1) constraining factor (xi) from 0.5 to 1.3, (2) tube width ratio (beta) from 1.0 to 1.75. The main objectives of these tests were threefold: firstly, to describe a series of tests on composite columns; and secondly, to analyze the influence of several parameters such as constraining factor and width ratio on the behavior of stub concrete-filled RHS columns. And finally, to compare the accuracy of the predictions by using the recommendations of LRFD (AISC. Load and resistance factor design specification for structural steel buildings. 1994), AIJ (Architectural Institute of Japan. Recommendations for design and construction of concrete filled steel tubular structures, 1997), EC4 (Eurocode 4. Design of steel and concrete structures, Part 1.1, General rules and rules doe building. 1996) and GJB4142-2000 (GJB4142-2000. Technical specifications for early-strength model composite structures. 2001). Experimental results indicate that the constraining factor and the width ratio have significant influence on both the compressive load capacity and the ductility of the steel tube. The loading capacity of the concrete-filled RIDS stub columns can be conservatively predicted by using LRFD, AIJ, EC4 and GJB4142-2000 recommendations. The GJB4142-2000 methods gave closer predictions of the test results than the LRFD, EC4 and AIJ methods, and are acceptable for the calculation of the section capacity for axially loaded concrete-filled RHS stub columns. (C) 2002 Elsevier Science Ltd. All rights reserved.