Numerical modelling of connections in composite frames
The main objective of this thesis was to develop numerical modelling procedures for composite connections and to use results generated in conjunction with data from other sources as the basis for the preparation of design procedures. The finite element method has been used for the numerical simulation of composite endplate connections. The developed model was verified by comparing both local measures of response and overall behaviour with test results. The validated model was then used in conjunction with theoretical analysis to study the behaviour of composite endplate connections for variable shear to moment ratios. This permitted the identification of those cases for which changes in the shear to moment ratio affects the connection's moment capacity. The model was also used in conjunction with theoretical analysis to study the effect of varying levels of axial column loading on the connection moment capacity. Results of both studies indicated a need for modifications to the equations of EC3 (for bare steel connections but which are also applicable to composite connections) that consider the interaction with column loading. These are: the equations for column web compression resistance, column web shear resistance and the bolt force. Using the FEM results, available test results and EC3 and EC4 equations for the determination of basic component forces, design procedures for composite flush endplate, finplate and angle cleated connections are proposed. Predictions from the design method have been compared with a total of 53 test and finite element results for the flush endplate connections (32 laboratory tests from 7 different sources plus a further 21 numerical results) so as to provide validation over the full range of parameters. These comparisons gave an overall prediction to test ratio of 0.99 with a standard deviation of 0.14, thereby demonstrating that the proposed method can accurately predict the resistance of composite flush endplate connections under a variety of different connection arrangements and loading conditions. Similarly, the prediction from the design method was compared with 6 finplate test results which gave an average prediction to test ratio of 1.06 with a standard deviation of 0.18. Comparisons for the angle cleated connection using 16 test results from 4 different sources gave an average prediction to test ratio of 0.98 with a standard deviation of 0.13. Theoretical studies have been performed to develop equations to predict the initial stiffness for composite endplate connections and these have been verified against test results. Suggestions to predict the available rotation capacity of flush endplate connections have also been made. This two methods has been combined with the moment capacity model to develop a prediction method for the overall behaviour of the flush endplate connections. The finite element method has also been used to develop a numerical simulation of non-sway composite frames. Comparisons of results show good agreement with the observed test behaviour. It has been found that it is possible to model the non-sway frames in a way that can predict the frame moment distribution, connection moment - rotation response and the beam load displacement history with sufficient accuracy. This provides an economic tool to study different aspects of the behaviour of composite non-sway frames. A numerical model has been developed for un-braced steel frames by simplifying the composite frame model. This model was verified using numerical results selected from the work of other researchers. Using the model for steel frames, studies were conducted for sway behaviour which provide guidance on behaviour suitable as a basis for developing design procedures.