Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Investigation of the rotation behaviour of hollow section beams
At present the limitations for the application of the different design models (plastic and elastic) to sections are given by b/t-ratios. These b/t-ratios are tabled in various standards and are controlled by the yield strength. It is known that the b/t-ratios are very conservative in particular for hollow sections, because no sufficient test results are available in this field. This restricts the application of a wide field of hollow section beams. Modern methods allow to check the rotation requirements and the rotation capacity for the section directly whereby all influencing parameters for the rotation capacity are taken into account (b/t-ratio, fu/fy-ratio, moment gradient, imperfections, types of fabrication, types of loading, etc.). This project is devoted to investigations on the moment-rotation characteristics of circular, square and rectangular hollow sections as well as concrete filled hollow sections. Four-point bending tests have been carried out for cold- and hot-formed square and rectangular hollow sections made of different steel grades. For circular hollow sections, which have also been investigated, two different test setups have been arranged. In the first test setup the beams have been tested in four-point bending. In the second test setup the sections have been tested in three- and four-point bending. Tensile tests to determine the characteristic yield strength should be carried out with coupon tests taken from a location representative for the 'mean value' of the actual yield strength distribution for all sections. In the case of hot-formed sections the distribution is almost equal. In the case of cold-formed sections the 'representative location' has been determined as the quarter point of a flange and the corner. Residual stresses have been measured for three section types: one hot-formed section and two cold-formed sections. It has been shown that they do not have an influence on the rotation capacity. Additional comparative tests have been carried out for square and circular thin walled hollow sections with and without concrete infill. These tests demonstrate that concrete infill reduces the tendency to local buckling and hence improves the rotation capacity. Failure may occur if the ultimate strain is exceeded.
Investigation of the rotation behaviour of hollow section beams
At present the limitations for the application of the different design models (plastic and elastic) to sections are given by b/t-ratios. These b/t-ratios are tabled in various standards and are controlled by the yield strength. It is known that the b/t-ratios are very conservative in particular for hollow sections, because no sufficient test results are available in this field. This restricts the application of a wide field of hollow section beams. Modern methods allow to check the rotation requirements and the rotation capacity for the section directly whereby all influencing parameters for the rotation capacity are taken into account (b/t-ratio, fu/fy-ratio, moment gradient, imperfections, types of fabrication, types of loading, etc.). This project is devoted to investigations on the moment-rotation characteristics of circular, square and rectangular hollow sections as well as concrete filled hollow sections. Four-point bending tests have been carried out for cold- and hot-formed square and rectangular hollow sections made of different steel grades. For circular hollow sections, which have also been investigated, two different test setups have been arranged. In the first test setup the beams have been tested in four-point bending. In the second test setup the sections have been tested in three- and four-point bending. Tensile tests to determine the characteristic yield strength should be carried out with coupon tests taken from a location representative for the 'mean value' of the actual yield strength distribution for all sections. In the case of hot-formed sections the distribution is almost equal. In the case of cold-formed sections the 'representative location' has been determined as the quarter point of a flange and the corner. Residual stresses have been measured for three section types: one hot-formed section and two cold-formed sections. It has been shown that they do not have an influence on the rotation capacity. Additional comparative tests have been carried out for square and circular thin walled hollow sections with and without concrete infill. These tests demonstrate that concrete infill reduces the tendency to local buckling and hence improves the rotation capacity. Failure may occur if the ultimate strain is exceeded.
Investigation of the rotation behaviour of hollow section beams
Untersuchung des Rotationsverhaltens von Hohlträgern
Sedlacek, G. (Autor:in) / Dahl, W. (Autor:in) / Stranghöner, N. (Autor:in) / Kalinowski, B. (Autor:in) / Rondal, J. (Autor:in) / Boeraeve, P. (Autor:in)
1998
167 Seiten, 154 Bilder, 48 Tabellen, 14 Quellen
Report
Englisch
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