Academic literature on the topic '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.

Thesis (Ph.D)--Civil and Environmental Engineering, Georgia Institute of Technology, 2009.<br>Committee Chair: Dr. Leroy Z. Emkin; Committee Co-Chair: Dr. Abdul-Hamid Zureick; Committee Member: Dr. Dewey H. Hodges; Committee Member: Dr. Kenneth M. Will; Committee Member: Dr. Rami M. Haj-ali. Part of the SMARTech Electronic Thesis and Dissertation Collection.

This thesis concerns the continuity in steel and composite frame and specifically the region of the connections. It reports on five main areas as follows: 1. Seven beam-to-beam connection tests were conducted to study the structural performance of composite end plate connections. Various parameters such as the types of connections, amount of reinforcement, beams sizes, and the degree of shear connection were investigated. The investigation confirmed a similar overall response of moment-rotation (M-φ) curves to beam-to-column tests and justified the restriction by current design codes of having partial shear connection in hogging moment region. A prediction method to estimate the initial stiffness of composite connection has also been proposed. 2. The effects of concrete encasement on structural response of end plate joints of slimfloor beams were investigated. Five specimens of beam-to-column connection of slimfloor were tested. Parameters such as end plate thickness and bolt sizes are included in the study. The results have shown that proper reinforcement and design are needed if the connections are to be considered as a composite joint. 3. Tests were carried out to improve the bond capacity of encased slimfloor. A total of six push-out tests each with different type of “shear enhancer” were performed. The load at initial slip is not greatly depend on the types of enhancer and there were indications that the resistance of the enhancer only became effective after slip, due to bond failure, had occurred. 4. As far as stability of composite beams in the negative moment region is concerned, local buckling has been identified as one of the problems. The action of reinforcement may reduce many hot-rolled section to be in Class 3. Studies were conducted on published data to explore the possibility of upgrading Class 3 to Class 1. The studies indicated that beams of Class 3 web showed the characteristics of beams with higher class if the connection was full strength. Many of the Class 3 beams used in composite beams can only be upgraded to Class 2 and not to Class 1. 5. A method applicable to the design of unbraced multi-storey frames to specified limits on horizontal sway deflection is proposed. Only simple calculation are required by the method and its application is illustrated by worked examples.

This study looks at the feasibility of using structural optimization techniques to address the problem of designing composite fuselage frames for crashworthiness. A key feature of any optimization strategy for increasing structural crashworthiness is a progressive failure analysis. Currently, the most widely used analysis methods for progressive failure of composite structures are considered too expensive computationally for practical optimization in today's computing environment. Developing an efficient analysis method for progressive failure of composite frames is a first step in the optimization for crashworthiness. In the current work a progressive failure analysis for thin-walled open cross-section curved composite frames is developed using a Vlasov type beam theory. A curved thin-walled composite beam theory is developed and a finite element implementation of the beam theory is used for progressive failure analysis. The accuracy and limitations of this analysis method are discussed. A model for progressive failure of the composite fuselage frame is developed from an extension of the laminate progressive failure analysis of Tsai-Wu. Comparisons based on a limited amount of available experimental data are encouraging. The first major failure event is captured by the theory, and the prediction of total energy absorbed follows the trend of the experimental data. It is believed that this accuracy is sufficient for preliminary design and optimization for crashworthiness. This progressive failure analysis is then incorporated into a frame optimization for crashworthiness based on the genetic algorithm method. The optimization methodology is demonstrated analytically to obtain frame designs with substantially increased crashworthlness. Laminate stacking sequence and cross-section shape are design variables for optimization<br>Ph. D.

An analytical and experimental investigation was conducted to study the design and fabrication of carbon fiber track bicycle frames. A finite element software was used for the geometry development, laminate configuration, and for predicting failure using the maximum stress criteria. A load case and boundary conditions simulating actual riding conditions were developed. The stresses in each of the composite layers were found to be lower than the allowable stresses because of a properly designed geometry and laminate. Two composite frames were fabricated using the hand lay-up technique, using unidirectional and woven carbon fiber pre-preg material over an internal foam core. Using static testing techniques and comparisons with traditional tubular frames, the carbon fiber prototypes were shown to be better in all rigidity aspects. Combining the experimental and theoretical results, a good understanding of the critical problems related to composite monocoque bicycle frame design was obtained.