P 81 - Underground steel structures - Information and recommendations for design, calculation and execution

P 71 - Investigations on connections of closed and open profiles made of high-strength steels As a continuation and supplement to project P 11 (same title), static and dynamic tests were carried out with flat specimens and with junctions of hollow sections made of the materials St E 460 and St E 690. In the node areas of structures made of such profiles, inhomogeneous stress states are effective which cannot be recognised with the usual calculation approaches in steel construction. Only by means of detailed experimental investigations is it possible to create a basis for the design of calculation proposals, such as those already included in the draft of DIN 18 808 for St 37 and St 52. Flexurally rigid frame corners and T-nodes were analysed under static load. The results of these investigations show that - the design diagrams (see also DIN 18 808 - draft) for rigid frame corners found within the framework of the research programme P 7o "Determination of the load-bearing behaviour of rigid frame corners made of rectangular hollow sections under static load" are also valid for high-strength steels if the specified dimensional limits are observed.the design formulae and diagrams for T-nodes made of St 37 and St 52 under moment, vertical and combined loading in the analysed parameter range are also valid for nodes made of high-strength steels. The test results also show that even 10 % higher ultimate loads could probably be permitted. However, in view of the relatively small number of tests, this additional increase should be dispensed with for the time being. In addition, fatigue strength tests were carried out with cross nodes and K-nodes from rectangular hollow sections made of St E 460 and St E 690 and compared with the results of steel grades St 37 and St 52. Finally, fatigue strength tests were carried out with prestressed bonded flat specimens made of St E 460 and St E 690 and comparisons were also made with St 37 and St 52. Some questions still to be investigated concern the areas of time and fatigue strength. The report identifies issues in this respect that should be investigated by further research. STUDIENGESELLSCHAFT FÜR ANWENDUNGSTECHNIK VON EISEN UND STAHL e.V. Publication: 1981 Authors: Prof. Dr.-Ing. F. Mang, Dipl.-Ing. Bucak, Ing. (grad.) Steid

P 70 - Determination of the load-bearing behaviour of rigid frame corners made of rectangular hollow sections (St 37, St 52) under static load With the increasing use of rectangular hollow sections in steel construction, the question arose as to the dimensioning of the non-rigid connections characteristic of this type of construction. One of these connections is the rigid, welded frame corner, an example of which is steel staircase construction. This paper reports on load-bearing capacity tests with mitre-cut hollow sections welded to form frame corners. In addition, tests with plate-stiffened frame corners are also reported, which considerably increased the load-bearing capacity of thin-walled profiles. Design recommendations are given for both types - stiffened and unstiffened - which have also been included in roughly the same form in the draft standard (yellow print) DIN 18 808 "Structures made of hollow sections under predominantly static loading", September 1981 edition. We would like to thank Prof. Dr Ing. F. Mang and his colleagues for their work. We would also like to thank the Arbeitsgemeinschaft Industrieller Forschungsvereinigungen e.V., Cologne, for covering a considerable part of the costs of this project. We would also like to thank the "Profile Joints" working group of the Studiengesellschaft für Anwendungstechnik von Eisen und Stahl e.V., which contributed to this research project through its suggestions, preparation and supervision. STUDIENGESELLSCHAFT FÜR ANWENDUNGSTECHNIK VON EISEN UND STAHL e.V. Publication: 1981 Authors: Prof. Dr.-Ing. F. Mang, Dipl.-Ing. Bucak, Dipl.-Ing. Knödel

P 52 - Moment-free connection to concrete-filled hollow section columns - Experimental investigations Extensive research is being carried out internationally in the field of composite columns. In Germany, the Studiengesellschaft für Anwendungstechnik von Eisen und Stahl e.V. (Study Society for Application Technology of Iron and Steel) initiated a wide-ranging investigation as early as 1974, which covered load-bearing capacity, construction and fire issues for various types of cross-section - concrete-filled hollow sections, hot-rolled I-sections with concrete encasement and concreted C-sections. Using the test results and their evaluation, as well as on the basis of extensive literature in this field, a draft was produced on the subject of "Regulations for composite columns", to which Prof. Dr.-Ing. Roik, Ruhr University Bochum, made a significant contribution. Hollow sections with concrete filling have the great advantage that formwork work can be omitted. In addition, they have advantages from an architectural point of view and can - if certain conditions are met - fully fulfil the requirements of fire protection when unprotected on the outside. This paper reports on tests and constructive solutions for beam connections to hollow section composite columns, which have already been used several times in practice. We would like to take this opportunity to thank Prof.Dr.-Ing. K. Roik and his colleagues for their work. We would also like to thank the "Composite Columns" working group of the Studiengesellschaft für Anwendungstechnik von Eisen und Stahl e.V. for their encouragement, preparation and supervision of this research project. STUDIENGESELLSCHAFT FÜR ANWENDUNGSTECHNIK VON EISEN UND STAHL e.V. Publication: 1981 Authors: Prof. Dr.-Ing. K. Roik, Dipl.-Ing. M. Breit