This thesis reports work carried out to investigate the adhesive properties of chlorinated-rubber based lacquers on mild steel. Tensile tests were used to measure the failure stresses of such coatings, and it was established that a mixture of cohesive and weak boundary layer failure occurred. Consideration was given to the influence of lacquer storage, film thickness, drying time and binder molecular weight on the failure stress of the coating. In Chapters 1 and 2 the theories of adhesion are discussed, the system under investigation is described and methods of testing the adhesive and cohesive strengths of coating/substrate systems are considered. The development of a suitable test method, preparation and testing of specimens are described in Chapter 3, and the experimental values of stress to cause failure of the coating are discussed. Chapter 4 describes the detailed surface analytical work which was carried out to establish the mode of failure of the coating, and investigate the inhomogeneities occurring within the cured film. It was found that the plasticiser migrated towards the lacquer/air interface as the film cured, leaving a "binder-rich" region at the lacquer/substrate interface. It was also found that chemical interaction occurred between the lacquer and the substrate, under certain circumstances, and in Chapter 5 these interactions are considered. Theoretical work was carried out to investigate the application of various expressions for calculating the Van der Waals forces acting between two molecules, to the system under investigation. This is described in Chapter 6. The numerical values of the Van der Waals forces obtained using these expressions are compared, and their relevance to the experimentally measured failure stresses considered. The conclusions which may be drawn from the results of the work described in Chapters 3-6 are considered in Chapter 7, and suggestions made of areas for further work.

In order to clarify the dependence of strain localisation on different parameters, a literature survey is presented covering the theory and observations of instability formation during deformation, dynamic recovery processes, mechanical testing, adiabatic heating and shear band formation. Several series of experiments were carried out, on titanium bearing steel and on an austenitic stainless steel , to determine the reasons of the inversion of the dependence of the strain to the peak in flow stress on strain rate observed at high strain rates. The materials were deformed under conditions of plane strain and axisymmetric compression, and torsion. Special techniques were developed in order to measure the distribution of strain and temperature within deforming plane strain specimens. In the strain distribution analysis, it was observed that the range of local strains is dependent on nominal strain rates, but the average value of the local strain either in the whole deforming region or the slip line bands depends only on the value of nominal strain. When the plane strain specimens were deformed with inserted thermocouples, it was found that both the overall temperature increase and the difference in temperature between different local regions of the specimen, increased with the nominal strain rate. It was shown that, at high strain rates, the stress-strain curve of any material will develop a peak in stress as a result of the increase of temperature due to deformational heating, without the occurrence of any strain instability. The results emphasise the complexity of deformation under plane strain compression, particularly at high strain rate, but it was possible to compare stress-strain curves obtained under plane strain and axisymmetric compression conditions when the effects of strain and stress distribution and of temperature localisation were taken into account.

In this thesis both analytical and design studies have been conducted on the behaviour of fully and semi-rigidly connected multistorey steel frames. Many topics have been addressed, current design approaches examined and new design methods proposed to allow for such effects based upon a first order linear elastic analysis, which is the most commonly used in normal design. These topics are as follows: 1) The well known amplified sway method (see BS 5950: 1985: Part 1) which can be used to incorporate the effect of the presence of axial loads on the behaviour of sway frames was studied. A modification to this method has been proposed and the validity of the proposed method was checked using an existing computer program [1] to verify the proposed method against a second order analysis. 2) The influence of the action of semi-rigid connections on frame behaviour was examined and the need to conduct a systematic investigation into the problem verified. A simple hand calculation method to incorporate this influence to any of the conventional design methods has been proposed. A second computer program [2] was slightly modified to suit the university of Sheffield IBM3083 mainframe machine and this program was later used in this study. 3) The stiffening effect due to partial sway bracing resulting from the presence of block or brickwork walls in a practical multistorey frame accompanied by the weakening effect due to the finite stiffness of semi-rigid joints on frame serviceability was investigated and a suitable design method is recommended. 4) The behaviour of columns in sway frames with and without partial sway bracing, resulting from the presence of infill panels in practical frames, has been examined. Design charts which can be used to predict a reasonably conservative estimation of the inelastic ultimate load of a framed column in a sway structure are given. These charts are particularly helpful in assisting a designer to make a reasonably good initial selection for the column section sizes in a flexibly connected frame. In addition an empirical formula has been proposed to incorporate the beneficial effect on the column behaviour resulting from the presence of infill panels in real steel frames. In order to conduct this study a computer program developed by Rifai [3] has been modified to simulate the behaviour of a flexibly connected sway subassemblages. 5) Finally general conclusions and recommendations for future work are given.

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