Experimental and analytical studies of cold-formed thin-walled frameworks with semi-rigid connections
The behaviour of symmetrical single and double storey frameworks, constructed with cold-formed thin-walled plain channel members and semi-rigid connections, is investigated both analytically and experimentally in this thesis. A method of analysis, which is based on the matrix stiffness method, is developed and written into a computer programme. Generalized relationships between forces and displacements at the ends of an element with semi-rigid connections are derived and presented in a matrix form. The analysis takes account of local and torsional flexural buckling, connection strength and full moment-rotation behaviour, axial load effects, member plasticity, initial imperfection and shortening due to flexure. Using the theoretical analysis, the full loading history of the framework can be traced up to the final failure load. Results are finally presented graphically and in tabulated form. Details of an experimental investigation, which was undertaken to obtain the moment-rotation relationship of connections of various stiffnesses, are given. From the experimental data, a standardized theoretical model capable of representing the full moment-rotation behaviour of the connections is developed. Results from the model are compared with the experimental data and the agreement is generally very good. The theoretical model is incorporated in to the theoretical analysis to account for the change in stiffness of the connection during loading. For the frameworks, an extensive experimental investigation was undertaken to ascertain the accuracy of the theoretical analysis. Details of the fabrication of the specimens, construction of the frameworks, testing equipment and procedures are also presented. Results of the framework experimental investigation are compared with the theoretical predictions. The agreement between theory and experiment is shown to be very close in general. Some wholly theoretical numerical results are also presented and discussed. The findings of the investigation are summarized and the main conclusions are listed.