Design and analysis of unbraced steel frames
The thesis examines the behaviour and design of unbraced steel frames with rigid and semi-rigid connections. An approximate hand method has been developed for the calculation of second-order elasto-plastic failure loads for single storey frames. Studies were carried out to propose limiting values of frame parameters, so that the first-order plastic theory can be used as a safe design method for single storey frames. A second-order e1asto-plastic computer analysis program has been developed. The program takes into account the main non-linear phenomena that occur in real frame structures. These include geometric non-linearity, material non-linearity and, the most important of all, the non-linear connection behaviour. The program can deal with any non-linear moment-rotation characteristic resulting from test data or analytical curves. The analysis program has then been used to check the adequacy of the wind connection design method. The program for static load collapse was further developed to investigate the response of the structure to cyclic loading. The program was used to investigate the incremental collapse behaviour, including alternating plasticity and shakedown of multistorey frames with rigid and semi-rigid connections.