Cam mechanisms have many applications in automatic machinery. Considerations of dynamic performance require the profile shape to be defined indirectly from the follower motion, the flexibility of timing and configuration introducing additional variables. Consequently the design and manufacture of new master cams using conventional techniques is laborious and expensive. Precision is essential since the follower motion is sensitive to minor dimensional inaccuracies and discontinuities of curvature. The object of this investigation is to simplify both the design and manufacture of a new master cam. The author's survey of previous work showed it necessary to establish the design sequence before the processes involving greatest effort could be isolated. His associated study of existing profile copying and generating devices found none which satisfied the criterion of extensive application, but identified weaknesses of previous designs. This thesis considers the adaption of the copying principle to manufacture cam profiles from the intrinsic shape of a leaf spring deflected to suit specified boundary conditions, so eliminating dependence upon co-ordinate data, complex transmissions and special templates whilst relying upon the repeatability of an instrument in preference to the positioning accuracy of a machine-tool. Profiles for two distinct follower motions can be derived by this means, their characteristics resembling those of SHM and cycloidal motion respectively. The characteristics are functions of the displacement equation. A search revealed no comparison nor experimental verification of previously published analyses of the elastica. Limitations of the previous analyses led the author to derive new solutions using the method of perturbations; these have the advantage of simple computation and give a direct solution for any intermediate position. Experimental studies showed good co-relation between theoretical and measured deflections. The attachments were designed and manufactured and profiles cut using this process.

The basic concept of Hybrid Active-Passive Constrained Layer Damping (HAPCLD) treatment was proposed by introducing active control to the concept of passive constrained layer damping configuration in the 1990s to compensate for weak points in active and passive controls by using their respective merits for more robust and stable control. Since then, combinations of various configurations and applicable control strategies have been proposed and studied in many engineering areas. However, there is still a need for a new modelling method to more easily establish models of HAPCLD treatment and its validation through control analysis and experiment with various structures from beams to curved plates. In this thesis, velocity feedback control strategy was applied to cantilever beams with four different configurations of HAPCLD treatment to check their applicability. Moreover, the application was expanded to flat and curved plates. Control results with each configuration for flat and curved plates were analysed by using self-established MATLAB codes based on the Finite Element Method (FEM) with the basic concept of a layer-wise approach for coupling each layer of structures and deriving Equivalent Single Layer (ESL) models. This new numerical modelling method was established by introducing coupling matrices based on a layer-wise approach to combine individual FE mass and stiffness matrices of each layer into one ESL model for a whole structure. Furthermore, these numerical models were supported by experiments in a lab. All measured data was compared with simulation results and they were confirmed in good agreement in general. In addition to this, the relation between mode shapes and control by piezoelectric patches occupying a broader area than an ideal actuator was studied to find the conditions for more stable control of flat and curved plates. In conclusion, as discussed for active control with beams, AC/PSOLD treatment, which consists of a piezoelectric actuator directly attached to a base structure and a stand-off layer with a viscoelastic core and elastic constraining patch laminated on the piezoelectric actuator, was clarified to give the most efficient and robust active control results for plates regardless of the curvature of all HAPCLD treatments dealt within this thesis as well. AC/PSOLD treatment could give similar reductions with smaller control gain in simulation. And, larger reductions were obtained with measured transfer functions in experiments than other configurations.

Current research with respect to the protection of civilian infrastructure against complex blast loading conditions is primarily focused towards the effect of external explosive sources. As a consequence, the general literature on internal building detonations and specifically in the context of protective design and assessment of structures against these loading conditions is incomplete. Existing guidelines developed for comparatively noncomplex external explosive blast remain unconservative when applied to internal building detonations due to blast wave confinement and complex interaction with structural components. In particular, reinforced concrete (RC) columns in internal blast environments are subjected to time-variant uplift forces coupled with lateral pressures leading to destabilisation and a critical loss of structural integrity. Research presented in this thesis provides an original understanding towards: (i) – the influence of transient uplift forces on the vulnerability of RC columns subject to lateral blast pressures and, (ii) – design and assessment of RC columns against the effect of time-variant coupled uplift and lateral blast pressures due to internal building detonations. Research in this thesis is based on advanced uncoupled Euler-Lagrange numerical modelling splitting the structural and flow solvers for maximum integrity and accuracy. High-resolution simulations of complex flow fields are analysed using the hydrocodes Air3D and Autodyn, whilst Extreme Loading for Structures [ELS] based on the Applied Element Method is used for modelling the transient-dynamic structural response of columns. These numerical techniques are comprehensively ratified and underwritten, both qualitatively and quantitatively, using published independent experimental test data. Verified numerical modelling is subsequently used to conduct a set of comprehensive parametric studies covering both vented (frangible perimeter walls causing pressure venting) and contained (non-frangible perimeter walls causing repetitive wave reflections) internal blast environments. Results of these parametric studies are thoroughly analysed with the use of multi-variable nonlinear regression analysis techniques and are presented in the form of separate assessment and design charts. This thesis also presents a set of column hazard charts developed based on the parametric studies. These hazard charts provide threshold combinations of TNT Equivalency and critical radial distance corresponding to different column damage levels ranging from ‘No Damage’ through ‘Low Damage’ and Moderate Damage’ to ‘Imminent Structural Collapse’. The output of this research will be of direct relevance to both practitioners and researchers involved with protective design of civilian and military buildings.

Offsite construction is considered a new method of building in Saudi Arabia in comparison to other developed countries. The aim of this research is to examine the main factors affecting offsite construction in Saudi Arabia in order to propose a feasible strategy for its wider implementation. The broad range of factors affecting the impact of its application, the reasons for its use, and the challenges it faces were extracted from the existing literature. As a result, each reflects a factor affecting offsite construction. To achieve the research aim, the researcher adopted a mixed method approach, combining Semi-Structured interviews and Questionnaires. The interviews were administered amongst 6 expert participants in the construction industry in Saudi Arabia, while 136 participants from this industry filled in the questionnaire. All of the data were gathered and analysed based on scientific methods of analysis. The interviews revealed many factors that affect the implementation of offsite construction in Saudi Arabia and highlighted that there are four main offsite construction techniques (Offsite preassembly, Hybrid system, Panelised system and Modular building); this was also confirmed by the questionnaire. The questionnaire revealed that an increase in labour productivity and product quality as well as an overall reduction in project schedule are the main attributes of offsite construction. However, there are many challenges facing offsite construction in Saudi Arabia, including inflexibility in making on-site changes, limited design options, associated costs and risks, low awareness and resistance to OCT. An ISM validation confirmed similar outcomes. All of these factors are discussed in relation to the literature review in the discussion chapter, based on which the researcher developed an OCT implementation strategy which he tested using the ISM methodology. In its investigation of the viability of offsite construction in Saudi Arabia, this study extends its scope beyond standard considerations of time and cost in construction, to examine these and other factors in the context-bound circumstances in which they are applied. This approach sets the background for a detailed examination of offsite fabrication in Saudi Arabia. This study considers the individual factors of cost, quality, environmental impact, negative perceptions, etc., and some of the implementation-related drivers and barriers. It also includes an examination of the social and cultural factors which could hasten the successful implementation of OCT, such as Saudi society’s capacity to collaborate by adopting an open-minded, questioning approach to sharing information and to innovate by anticipating and responding to change.

The main contribution of this study is to evaluate the effects of hydrocarbon contamination of soil with respect to geotechnical and geochemical properties and their impact on human health resulting from the Iraqi invasion of Kuwait in 1990. To fulfil this goal, the geotechnical and geochemical characteristics of soil at a dry oil lake have been investigated. The Human Health Risk Assessment (HHRA) was investigated utilising Risk Integrated Software for Soil Clean-up Version-5 (RISC-5) to evaluate the effects of hydrocarbon contamination on human health via ingestion of soil, dermal contact with soil, ingestion of vegetables, inhalation of outdoor air and inhalation of particulates pathways. In order to study these variations, two neighbouring sites at Al-Magwa area on the Greater Burgan Oil Field were selected. The first was chosen for a dry oil lake scenario, and the other adjacent site as an uncontaminated baseline control. Geotechnical tests were implemented on samples taken at different depths from both sites. These included Atterberg Limit, Particle Size Distribution (PSD), permeability and shear strength. Electronic micrographs were also taken for the upper layer (0.0 m depth). The geochemical investigations included Hydrogen Ion Concentration (pH), water soluble Chloride and Sulphate content, Vario Macro Elemental Analysis (EA) and Gas Chromatograph Mass Spectrometry (GC-MS). GC-MS was carried out to determine the specific hydrocarbon compounds and their concentrations within the soil. These values formed the basis of a HHRA. The geotechnical results show that hydrocarbon contamination modifies the PSD together with a decrease in the angle of internal friction (φ). The geochemical results confirm that the hydrocarbon contamination causes a change in the pH, with the Chloride and Sulphate contents and hydrocarbon concentrations decreasing with depth. The HHRA demonstrated that certain hydrocarbon compositions at elevated levels encountered in the dry oil lake site had potential effects with regard to non-carcinogenic risks. The geotechnical and geochemical characterisation data used in this study are also analysed quantitatively using IBM SPSS Statistics in order to support robust results. The statistical analysis confirms that all the results are solid and compatible.

Bistable Reeled Composite (BRC) booms have the potential to be used as lightweight structural elements for a number of space applications. This thesis details an approach for increasing the natural frequency and stiffness of extended BRCs. The motivation for this research is the desire to increase the scalability of a flexible “roll-up” solar array which, in its deployed state, consists of two cantilevered BRCs supporting a flexible Photo Voltaic (PV) cell-covered blanket betwee n them. A parametric study has been presented, which analysed the effects of design parameters on the vibration characteristics of a single boom using a Finite Element (FE) approach. A numerical model was combined with a nonlinear constrained optimisation to maximise the natural frequency of BRC booms with respect to the fibre orientation angles and ply discontinuity locations, under the constraints of the physically achievable braid angles and constant coiled diameters resulting from the deployment mechanism design. The results demonstrate that careful selection of the fibre orientation angles and introducing a step change in the number of plies at strategic positions along the boom length can significantly increase the natural frequency. For instance, the natural frequency of a four-carbon/epoxy-nominalbraid-ply boom (L = 5.1 m, R = 38 mm, and β = 345◦) has been improved by more than 50%. The agreement between the natural frequency values for the complete solar array and the corresponding individual BRC booms indicates that the optimised solutions for a single boom model are applicable to the complete model for the first (cantilever) mode. Experimental verification of the vibration characteristics of optimised BRC booms has also been conducted. Finally, a dynamic stability analysis of the optimised BRC booms under bending has been carried out using FE simulation, to quantify the maximum angular acceleration that they can withstand before failure. The optimised BRC booms exhibit a higher resistance to bending during a spacecraft manoeuvre.

The monopile is the dominant foundation type for offshore wind turbines, with current design guidance based on knowledge transferred from the oil and gas industry. Whilst there are some similarities between wind turbine and oil and gas pile design, there are also a number of key differences. Notably, offshore wind turbine monopiles are subjected to many cycles of large horizontal loads during their lifetime, whereas such loading conditions are not as prevalent in oil and gas design. As a result, the pile response due to this cyclic loading is poorly accounted for in current practice. This thesis presents experimental and theoretical research, aimed at improving the understanding of the behaviour of rigid monopiles in cohesionless soils, when subjected to lateral cyclic loading. The experimental work involves laboratory floor model tests, scaled to represent a full-scale wind-turbine monopile. The test programme is designed to identify the key mechanisms driving pile response. It is divided into four main parts, investigating loading rate effect, hysteretic behaviour during unloading and reloading, as well as pile response to long-term single and multi-amplitude cyclic loads. In particular, the results show that the pile response conforms to the extended Masing rules, with permanent deformation accumulated during non-symmetric continuous cyclic loads. This ratcheting behaviour is characterised by two features: first, the ratcheting rate decreases with cycle number and depends on the cyclic load magnitude and secondly, the shape of the hysteresis loop tightens progressively, involving increased secant stiffness and decreased loop area. Tests investigating multi-amplitude loading scenarios prove that the interaction between these mechanisms describes the pile response. Finally, the continuous cyclic test results are interpreted using the p-y method combined with the Degradation Stiffness Model, and this shows a good fit to the observed pile deformation. The key experimental findings are used for the development of a constitutive model that captures ratcheting while conforming to the observed Masing behaviour. The model, called HARM, is rigorous yet simple, and is framed within the hyperplasticity approach presented by Houlsby and Puzrin (2006). The model is tuned to capture the macro response of the pile under monotonic and cyclic loading, and is calibrated using the experimental data. The results demonstrate that HARM can successfully reproduce the main elements of the pile response with high accuracy. The method could easily be within common design approaches, such as the p-y method.

No description available.

Drinking water infrastructure functions to provide a service to meet customer demands and health requirements. Pipe repairs are one of the biggest challenges of ageing water infrastructure in the UK and world wide. Pressure transients resulting from sudden interruptions of the movement of the water can be caused by routine value operations. In a single pipeline one extreme event can burst a pipe. However the occurrences and impact of pressure transients in operational water distribution systems were not currently fully understood. This research developed new insights and understanding of pressure transient occurrences and their contribution to observed pipe repair rates. A large scale field monitoring program, including deploying and managing high-speed (100 Hz) instrumentation for 11 months, was designed and implemented to cover 67 district metered areas (DMA) subdivided into 79 pressure zones. In total 144 locations were monitored. The data was analysed using a novel method, termed transient fingerprint. This allowed the identification of discrete pressure transients and their three fundamental components (magnitude, duration and numbers of occurrences) leading to a quantitative interpretation of pressure transients. Evolutionary polynomial regression modelling was used to assess the impact of directly measured pressure transient data in context with static pressure, age, diameter and soil variables on 64 cast iron pipes. The analysis suggested that high magnitude, short duration repeatedly occurring pressure transients can have an adverse effect on the pipes. The extrapolation of pressure transient analysis into 7978 cast iron pipes showed inconclusive results suggesting that more accurate pressure transient data is required for each pipe in the network. Additional analysis carried out on 25 asbestos cement pipes, with actual measurements of pressure transients for each pipe, confirmed an adverse effect of pressure transient on water network observed in cast iron pipes. This research has provided an understanding of the occurrence of pressure transients that has implications on pipe management strategies. Mitigation techniques to locate pressure transient sources based on the project outcomes could be utilised to better manage distribution systems and ultimately reduce future pipe replacements and associated costs.

This thesis primarily aims to explore the flexural behaviour of reinforced concrete beams subjected to different loading types. Both bonded and partially debonded (in the maximum moment zone) reinforced concrete beams under static sustained and repeated loading were investigated. Information relating to surface strains and mid-span deflection were continuously recorded for a period of 90 days so that meaningful comparisons could be made between the structural displacements of the beams tested under different load levels. The range of the sustained load applied varied from that corresponding to the first cracking moment to that required to produce a stabilised crack pattern. The experimental outcomes show that the long-term mid-span deflection of the reinforced concrete beams where the reinforcement was artificially debonded from the concrete is substantially higher than that of bonded reinforced concrete beams under sustained loading. For beams subjected to repeated loading, the amplitude of the repeated loading was deemed to be around one eighth of the sustained load. The bond between concrete and steel in reinforced concrete beams subjected to a repeating load can be significantly damaged due to the loading even though the frequency is relatively low (i.e. 0.2 Hz). On the other hand, and more unexpectedly, for the cyclically applied loading there was no substantial difference between the observed ultimate deformations of the bonded and debonded beams. Moreover, there is a linear relationship between the number of cracks and the shrinkage deflection. Beams having a higher number of cracks develop more deflection due to shrinkage. Nonlinear finite element software (Midas FEA) was used to simulate the experimental tests. It was found that a numerical-experimental match could only be achieved after applying necessary modifications to the shrinkage strain distribution along the beam section. In addition, the capacity of the software to separate the shrinkage and creep deflection clearly allows the relationship between number of cracks and shrinkage to be observed, and confirms what was observed in the experimental investigation.