published_or_final_version / Civil Engineering / Master / Master of Science in Engineering

published_or_final_version / Civil Engineering / Master / Master of Science in Engineering

published_or_final_version / Civil Engineering / Master / Master of Science in Engineering

published_or_final_version / abstract / Computer Science / Doctoral / Doctor of Philosophy

published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

The increasing demands placed upon design engineers to evolve optimal solutions to prescribed problem specifications necessitates more definitive analysis of system response to modifications.Traditional solution techniques including discretised methods are required to be repeatedly evaluated in multiple re-analysis solution environments in the search for optimal behavioural response. Modern developments in sequential linear programming techniques in both unconstrained and constrained environments have enabled the methods of optimisation to be applied in a structural context.Such advances are now being limited by the present state of solution to criterion and constraint functions. The state of the art in structural optimisation is reviewed and the application of current methods in the presence of discontinuities examined.The extension of such methods to the discretised problem is advocated.The search for an effective and economical re-solution vehicle is described with reference to the classical formulation of sensi tivi ties defined in a discretised context. The development of a solution technique based on sensitivity is described and limitations examined.The extension of sensitivities into the clearly defined non-linear state with large design variable changes is discussed and the development of a residual correction technique to linearise the sensitivities documented.Utilising residual correction the sensitivity method is extended into the concept of adjoint structures and predictive solution models for design variable changes. Quantitative and qualitative techniques for design performance assessment are evolved and an interactive program developed to graphically display the effect of design variable changes on design parameter response. A new design philosophy based upon design system syntheais is advocated and demonstrated wi th reference to particular design problems.Exploratory work is discussed with reference to the general application and the interfacing of the developed software system with alternate systems.

The majority of studies on European integration focus on the implementation of EU policies and regulations at the national or regional levels or on the influence of national and regional institutions in ED policy-making (Anderson, 1990; Tranholm-Mikkelsen, 1991; Geyer, 1996; Moravcsik, 1993; Marks, 1996; Majone, 1997). A smaller number of studies report on a series of changes appearing at local government level and connect them with a changing environment at the ED level and with the increasing importance of the EU funding programmes (Martin and Pearce, 1993: Goldsmith, 1993; John, 1996: Sutcliffe. 1997). However, the use of a top-down perspective has limited the findings of the previous research. The main objective of this thesis is to expand the knowledge on the phenomenon of ED funding within local governments, adopting a bottom-up approach, where changes appeared at the local government level, which were not included in EU directives, regulations and policy proposals, but represented a consequence of a changing order at the European arena. The research question asked in the study is: "Why do some local governments succeed and others fail in applying for EU funds?" Little empirical research has been conducted in order to understand the ED funding procedures followed by local government organisations, and how those procedures affected the organisations themselves and their employees. The study's objective is to build a theory exploring the process of competing for new types of funding within local government organisations. A theoretical framework is proposed at the beginning of the study which connects the phenomenon of EU funding with the presence of three important constructs: Europeanisation, networking and entrepreneurship. These constructs were explicitly measured in the interview protocol. From the analysis of the data, the constructs emerged as related to the success in ED funding within local governments through a causal relationship.

The following work describes the measurement of longitudinal residual stresses in hot finished structural steel hollow sections. All samples were supplied by the Tubes Division of British Steel Corporation (B.S.C.)and include circular and rectangular profiles manufactured by all of the methods employed by B.S.C. A total of sixty-eight profiles were examined. The technique used to determine the longitudinal stress state was the slicing method with strain release measured by mechanical extensometers. A new experimental method has been developed for the rectangular sections, where access to the inside corner area was restricted. The effect of these measured residual stress values, or idealisations based on them, on the behaviour of axially loaded pin ended columns is then examined by the development of inelastic column buckling computer programs. Various iterative solution routines are compared and a new accelerated relaxation procedure is developed. The relative effects of material and geometric imperfections on column behaviour are examined and the results obtained compared with existing and proposed column buckling design methods. One of the analysis programs is extended to cater for the application of primary bending moments at the ends of the columns and results obtained compared with existing design equations for beam-columns and modifications are suggested. The column buckling behaviour of hot finished hollow steel sections is also compared to geometrically similar profiles manufactured by cold forming or by welding. The phenomenon of local buckling of sections with relatively thin walls is also theoretically examined by utilising a non-linear finite element program. The effects of various parameters on local buckling are examined, including corner geometry, stiffening effect of stockier adjacent faces, initial geometric imperfections and residual stresses. Existing design rules for local buckling are described and comparisons made.

The Cathaysia Block, located in southeastern China, is characterized by a widespread magmatic belt, prominent NE-striking fault zones and numerous rifted basins filled by Cretaceous-Eocene sediments. The geology denotes a transition from an active to a passive margin, which led to rapid modifications of crustal stress configuration and reactivation of older faults in the Cathaysia Block. However, the timing and kinematics of the active-passive margin transition need to be better constrained. The SW Cathaysia Block, near the coastal area of the South China Sea, is selected for studying the transition. There are two major geological units in this region: the Nanling Range and the Yunkai Terrane. The Nanling Range is a magmatic belt composed of granitic plutons with formation ages ranging from Caledonian to Cretaceous. The Yunkai Terrane is a metamorphic terrane of Caledonian age. Thirty zircon fission-track (ZFT) data and thirty apatite fission-track (AFT) data were obtained from the granitic plutons in the SW Cathaysia Block. The distribution of ZFT ages shows two episodes of exhumation of the granitic plutons: the first episode is found to occur during 170 Ma – 120 Ma and affect the SW part of the Nanling Range; the second episode, a more regional exhumation event, occurred during 115 Ma- 70 Ma. The AFT dating results show a general cooling sequence from south to north during Late Cretaceous – middle Eocene, contrary to the conventional passive margin model. Numerical geodynamic modeling of subduction zone indicates that (1) high slab dip angle, high geothermal gradient of lithosphere and low convergence velocity favor the subduction process and the reversal of crustal stress state from compression to extension in the upper plate; (2) the late Mesozoic magmatism in South China was probably caused by a slab roll-back; and (3) crustal extension could have occurred prior to the cessation of plate subduction. The numerical model results of lithospheric deformation associated with subduction process reveal that granitic crust is easily deformed compared to gneissic crust. The results could be used to explain the observation that the granite-dominant Nanling Range was exhumed earlier than the gneiss-dominant Yunkai Terrane. In addition to the difference in geology between Yunkai and Nanling, the heating from Jurassic- Early Cretaceous magmatism in the Nanling Range may have softened the upper crust, causing the area to exhume more readily. On the other hand, the numerical models of crustal extension with pre-existing faults dipping ocean-ward demonstrate a trend of fault reactivation sequence from south to north. Assuming that granite exhumation in the Cathaysia Block was mainly a product of rifting and fault reactivation, the numerical models support the AFT results. The integrated FT dating and numerical model results suggest that roll-back of the subducting paleo-Pacific Plate slab during Late Cretaceous is likely to be the driving force of the transition from Mesozoic subduction to Cenozoic extension in the Cathaysia Block. The timing of the transition is suggested to have taken place at ~ 92 Ma, according to a rapid cooling as revealed by the thermal history modeling of AFT length data. / published_or_final_version / Earth Sciences / Doctoral / Doctor of Philosophy

The development of mixed and hybrid models provides viable alternatives in finite element structural analysis which overcome the shortcomings of conventional displacement and force methods. In this thesis, a mixed triangular finite element model in two-dimensional stress analysis is studied. The mixed finite element model has several features which are distinct from those of conventional methods: (i) the use only of mid-side nodes; (ii) a global coordinate system is not required; (iii) nodal variables include both forces and displacements; (iv) the element matrix consists of a mixture of stiffness, flexibility, equilibrium and compatibility coefficients; (v) the ability to deal with incompressible materials; (vi) internal equilibrium and compatibility are satisfied; (vii) the entire stress field of the assembled structure is in equilibrium; (viii) formulation of element equations is not based on an extremum principle. The derivation of element matrix equations for small-strain, small-displacement linear-elastic analysis is discussed and a scheme for assmebling the final set of algebraic equations is presented. Accurate and balanced results for both stress and displacement are obtained for a number of problems in plane elasticity including thermal strain and body-force problems. The ability of the mixed element to deal with incompressible materials makes it useful for the computation of collapse loads in elastic-perfectly plastic analysis, for example in undrained soil mechanics problems. Ideal plastic behaviour is approximated by the use of an extremely soft incompressible material. This approximation enables an incremental plastic stress-strain matrix to be written down, relating a plastic strain-increment to an imposed stress-increment in the ideal plastic range. The performance of the mixed element in elastic-perfectly plastic analysis is studied and numerical results are compared with those obtained by analytical techniques and the displacement finite element method. The use only of mid-side nodes in the mixed model has the advantage that a global coordinate system is not required in the analysis. This makes it relatively simple to follow the behaviour of structures in large-deflection problems. Examples are studied to investigate how the mixed element works in small-strain, large-deflection problems.