Plastic Design of Braced Frames Allowing Plastic Hinges in the Columns - Investigation of the Stresses in Rails

摘要

The report consists of two papers. In the first, the rotational capacity of steel columns in braced frames is investigated. The behavior of a braced portal frame up to collapse is examined. Requirements for rotational capacity of the columns according to some existing standards are scrutinized with the aid of calculated relations between bending moment, normal force and angular rotation of columns. An alternative approach is also presented, enabling a simple check of rotational capacity to be performed with the aid of a table giving values to the rotational capacity of a column, depending on slenderness, axial load and ratio of end moments. The application of this new method of analysis is illustrated with two examples. In the second paper, the flexural behavior of a rail under purely vertical load acting in the plane of symmetry is investigated. For this purpose a rail of NP 46 standard section was subjected to experimental research with the aid of electrical resistance strain gauges in the Laboratory for Highway and Railway Engineering (Stevin IV), Delft University of Technology. Furthermore, the flexural stresses in the rail due to the above-mentioned load were analysed with the ICES/STRUDL application package, version 2. The two methods of determining the flexural stresses were found to be satisfactorily serviceable for the purpose and to yield comparable results.