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No description available.

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No description available.

In the last two decades there has been an increasing interest in the development of inflatable structures on account of their potential applications in the erection of space and under-water structures. The stability of inflatable structures for use in the fluid environment is founded on such advantages as light weight, ability to carry the environmental forces efficiently by direct tensile stress and abiIity to utiIize the water pressure to counterba lance the gas pressure. The extensive possible applications of inflatable structures in ocean technology have emphasized the demand for investigations aimed at better understanding of the structural and hydraulic behaviour of these structures. The present study is concerned with the structural and hydraulic analysis of a gas-inflated membrane structure fully submerged in water. The structural analysis of such a structure involves the determination of the profile shape and the tension in the membrane for given inflation and load conditions. This is carried out by the numerical solution of the differential equations of equilibrium of the membrane. The results have been confirmed by an experimental investigation. The incorporation of a two-way set of reinforcing cables has also been considered. The effect of the spacing of the reinforcing cables for various membrane geometries is studied. Also, the effect of partially drawing-off the internal gas of the inflated structure as a result of which, water enters the container, is examined. The hydraulic aspect of this study is mostly concentrated on the investigation of the effect of waves and currents on the proposed structure. Models of the proposed structure have been tested using wind tunnel and wave flume. The results show the effects of currents and waves on the pressure distributions around the models and on the inertia forces. The changes in the shape of the structure and the tension in the membrane due to the effect of a uniform current are assessed. The scouring action of the current has also been investigated experimentally and qualitative results have been obtained. A general computer program has been developed which can handle structures with up to 300 joints and can be used efficiently for the analysis of many types of cable and suspended structures under different loading conditions. Numerical results are generated for the proposed inflated cable-reinforced structure. Finally, the application of such structures for the storage of hydrogen produced from the electrolysis of water using surplus electricity and the storage of associated gas from offshore oil wells is considered. The work carried out in this thesis shows that the proposed structure is feasible and the results presented may be used as a gUidel ine in the design. However, more investigation is required before a final design can be attained.

Ground anchorages are the main support for the structures as tunnels, mines and retaining walls. Both BS8081: 1989 and current practice suggest that there is a need for anchorages to be installed cost-effectively and monitored efficiently in terms of their long-term condition. An EPSRC research project was carried out to investigate the application of the GRANIT system developed at the University of Aberdeen, a proven viable long-term condition monitoring system for rock anchorage, to soil anchorages incorporating soil behaviour.

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.

There is a current trend towards ever more slender concrete floor structures, which is resulting in more frequent problems with their vibration serviceability. Predictive methods for vibration serviceability must consider not only the structures themselves, but also the non-structural elements which are attached to them, as these may have a significant effect on the dynamic characteristics of the floor structural system. As there has been very little past research in this area, this thesis describes an investigation into the effects of raised access floors on the vibration serviceability of long-span concrete floors. The development of a new modal testing facility based on electrodynamic shaker excitation, which was capable of producing high quality estimates of the modal properties of full-scale floor structures, is described. This was subsequently utilised to determine the modal properties of three full-scale floor structures, before and after the installation of various configurations of raised access floors. The response of these structures to controlled pedestrian excitation was also measured. Realistic finite element models of all structures were developed and updated using the results from the experimental work. These were subsequently utilised for investigation of the experimentally measured effects of the raised access floors. It was found that raised access floors had only minor effects on the modal properties of the long-span concrete floors. Reductions in natural frequencies due to the increased mass were, to some extent, offset by the slight increases in stiffness following the installation of the access floors. Modal damping ratios increased for some modes of vibration, but these changes were rather unpredictable and hence they were too unreliable to be used in design. The response of the structures under controlled pedestrian excitation reduced following the installation of various configurations of raised access floors. The reduction appeared to be greater for relatively deep access floors (500 - 600 mm) than for relatively shallow access floors (150 - 200 mm). Therefore, it is recommended that the effects of access floors may be included in vibration serviceability analyses by applying a reduction factor to predicted responses calculated by assuming a bare floor. The proposed reduction factors are 0.9 for access floors where the finished floor height is less than 500 mm and 0.8 for access floors where the finished floor height is 500 mm or greater.

In this thesis a brief history of dynamic pile analysis methods and the associated background theory are presented. In addition an unpublished rigorous mathematic proof of the Case method and new general theoretical model for dynamic pile analysis, developed as the Aberdeen method, are given. The dynamic and static response of model concrete piles in dry sand to impact and static loads have also been investigated experimentally and the results are reported in this thesis. Pile response has been found to be crucially dependent on the damping in the system. The method of modal analysis has been found to be the best approach to determine the damping factor of both the onshore and the offshore piles and is discussed in detail. A theoretical relationship between the initial and the reflected stress waves and the dynamic point resistance is used to calculate the force-penetration relationship and nonlinear parameters for the special case of pile points on dry sand. The shock relation, equations of motion and compatibility of the dynamic measurement at pile top are given by the Aberdeen method. This method gives a mathematical description of the behaviour of impact response which has not been achieved in either the Case or the TNO method. At present, the Case and TNO methods are used to investigate the integrity of piled foundations by means of the impact concept. This thesis introduces a third method, the J-integral method in the study of piled foundation. In addition, the thesis also gives a theoretical explanation to the TNO method which have not been provided elsewhere.