This research investigates the nonlinear response up to collapse of masonry arches and arch bridges using advanced numerical descriptions. Past research has shown that the mesoscale modelling approach for brick-masonry, where bricks and mortar joints are modelled separately, may offer a realistic representation of the mechanical behaviour of masonry components. However, because of the significant computational cost, thus far the use of this modelling strategy has been mainly restricted to 2D analysis of masonry arches and arch bridges. In some cases this may lead to a crude representation of the response which is inherently three-dimensional, especially when the analysed structure is subjected to eccentric loading or is characterised by a complex geometry (e.g. skew arches). In this work, masonry arches and arch bridges are analysed using a partitioned mesoscale approach, which enables the use of a detailed model for describing material nonlinearity at structural scale. This is combined with a partitioned approach allowing for parallel computation which guarantees computational efficiency. In the 3D mesoscale description, brick units and mortar interfaces are modelled separately accounting for the actual texture and arrangement of masonry. 3D elastic continuum solid elements are used to model brick units while mortar interfaces are modelled by means of 2D nonlinear interface elements. In analysing masonry bridges, the backfill material is modelled as an elasto-plastic continuum, while the physical interface between the continuum and mesoscale domain for masonry is represented by nonlinear zero-thickness interface elements allowing separation and plastic sliding. The proposed modelling approach has been applied to the analysis of multi-ring square and skew arches and masonry arch bridges. The numerical results, which also include numerical-experimental comparisons, confirm the accuracy of the adopted numerical strategy. Moreover numerical simulations have been performed to investigate the effects of the arch geometry, loading positions, material characteristics and potential settlements at the supports. The results obtained offer important information and a detailed description on the complex response of these critical structural systems under different loading and boundary conditions.

The reliability of project estimates is dependent on a number of factors that can be classed as exogenous or endogenous to the estimator. The exogenous factors comprise information, environment, technology, methods and processes, which are external to the estimator. The endogenous factors reflect personal characteristics associated with the estimator and consist of aspects such as judgement, preferences and personality. Construction's effort to improve the estimating function has addressed both the practice of, and process of delivering the estimate. Much of the effort, however, has been addressed at aspects of estimating that can be considered classed under exogenous factors. This includes the use of technology to improve both the accuracy of computation and the speed for generating the estimate. Notwithstanding progressive improvement achieved in estimating from addressing such exogenous factors, most project-oriented industries still suffer from unreliable estimates. Although the problem of unreliable estimates is a worldwide phenomenon, it reflects more starkly in many developing economies, where its effect is much more striking. Understanding the root causes of the persistence of unreliable estimates would therefore, call for a focus on factors other than the exogenous ones that most improvement and development efforts have focus on. The study, which formed the basis of this thesis adopts the position that any improvements in reliability, beyond what the exogenous-based developments have achieved so far, lies in the contribution that estimators can make by addressing their endogenous factors. For that position to be valid, the study showed that the personality characteristics of various estimators produce different levels of reliability. Three endogenous factors, experience, qualification, and personality archetype (or trait) were employed to explore the relationships with estimating reliability. A quantitative research approach was adopted for the investigation, as the nature of evidence required was primarily objective, to substantiate the argument that different levels of particular endogenous factors produce different reliabilities in estimating. Data for the study was obtained from Ghana. Two categories of sample data were collected through stratification of the population, followed by systematic sampling methods. The two samples were a control group, comprising estimators with more than or equal to ten years experience; and an observed (or study group), made up of estimators with less than ten years experience. An instrument based on a self-reporting protocol was developed and utilized in the elicitation of data from both groups.

The rapid expansion in the construction industry worldwide has placed more pressure on the available natural resources, as the various construction activities and the services they require, increasingly draw on supplies of water and energy. The provision of these utilities and their continual maintenance activites within a building, promote human daily sustenance, and economic development generally, but the exploitation of these resources, their environmental impact, socio-economic implications, and sustainability, all necessitate proper management. Indeed, sustainability has now become the cornerstone for effective building services infrastructure and building construction management. It is against this backdrop that this study, which focuses on building services infrastructure and construction activities management, is set. The study aims to integrate the sustainability agenda in this context as a basis for achieving sustainable development goals. Increasingly, building services infrastructure processes and the interdisciplinary engineering fields cannot operate optimally without the incorporation of the sustainability agenda as a core management consideration. In pursuit of its aims, the study has employed various theoretical propositions, suitable methods, and frameworks, all aimed at addressing the sustainability issues as a way forward. The current technologies and management techniques related to building management do already offer sustainable and good quality service delivery, but the findings from this study have yielded value added contributions capable of promoting greater success in the drive for sustainability, by employing the sustainable engineering infrastructure (SEI) model, sustainability index matrix (SIM), and partial differential equation techniques. The SEI model was used in evaluating building services infrastructure characteristics within the UK and Nigeria in the study phases I– IV, and the outcomes are presented. Life cycle assessment (LCA) and life cycle costs (LCC) methods were also applied to examine building services infrastructure systems and their performance in the study phase V. The LCA phase in this study considered ten environmental impacts during the construction, operation (use), maintenance, and the end-of-life phases of six buildings. The LCC technique appraised the use of construction materials, water, energy, and utilities to avoid duplication that leads to unnecessary costs in the aforementioned phases of buildings. The results of the different analyses are presented. Energy and utilities usage, together with carbon footprint management evaluation in both the healthcare and education sectors in the UK are also shown in the study phase VI. In appraising these scenarios, the partial differential equation method was adopted, generating results for the healthcare and education sectors of 0.74 and 0.62 respectively, which expresses a good degree of reliability of performance within these two particular contexts. In phase VII of the study, interviews with experts from academia and industry have corroborated the evidence secured from other phases of the research. There is also a novel discovery in this study, in its use of the SIM function which is able to provide a corresponding sustainability index result for buildings/facilities performance in respect of critical and strategic management decisions. The SIM has defined the sustainability index from probability theory within the limits of 0 ≤ Suv ≤ 1 for any given system function. The SIM and SEI models have been applied within some phases in this study based on the acquired data and the results are indicated. Additionally, there is a proposed algorithmic project life cycle framework with an allowance for either on/offsite recycling processes in managing building infrastructure challenges. In its scope, the study focuses on buildings (facilities) only, since the non-integration of sustainability ethics represents the major challenge undermining the building services infrastructure success. With this focus in mind, this study has delivered improved knowledge and understanding of the proper applications and management of building services infrastructure systems. This has been underpinned by the three themes of sustainable development for the present and future generations.

The work in this thesis consists of a study of the behaviour of concrete under uniaxial tension with regard to both strain development under external loading and short- and long-term failure. A method was first developed for the accurae short- and long-term uniaxial tensile testing of concrete and has been applied throughout the investigation. As a result of this work, a mechanism has been proposed within a framework of a seepage-plastic the tensile creep and failure of concrete. A rheological model has also been suggested to describe this mechanism. The tensile creep of air drying concrete was larger than that expected in compression but smaller when the concrete is stored sealed or under water. The creep of sealed and immersed concrete reached limiting values within two months while that of air drying concrete continued for a much longer tie. in other respects tensile creep behaviour was similar to that in compression.The creep of sealed concrete was about half that of immersed concrete and as low as 0.1 of that of air drying concrete. A relationship has been obtained between ultimate strength and the period of sustained loading. This relationship is similar to that previously obtained for concrete in compression but the reduction of strength due to long-term loading is greater than than for compression and can be up to 50 per cent of the short-term strength. This relationship is considerably influenced by the storage conditions of the specimen and the type of aggregate employed. The long-term strength of sealed concrete has been found to be up to 50 per cent higher than that of water-immersed concrete made with gravel aggregate while the short-term strength was about 15 to 20 per cent higher. This was not found to be so for concrete made with crushed granite aggregate. A limiting positive ultimate strain of 70 to 90 microstrain due to external loading was observed for all gravel concrete tests, short- or long-term but higher values were measured on granite concrete.

No description available.

An experimental and theoretical investigation of the strength of welded T-joints has been carried out, and the following tests were conducted:- 17 No. tests for ultimate axial strength (Pu) 17 No. tests for ultimate bending strength (Mu) 71 No. tests for combined axial and bending strength The parameter ranges of the tests were:- brace diameter/chord diameter: 0.42, 0.53, 0.67, 0.77, 1.0 chord diameter/chord thickness: 18, 21, 23, 32 brace thickness/chord thickness: 0.63 - 1.4 All test specimens were steel to BS Grade 43C, with an average nominal yield strength of 350N/mm[sup]2. The interaction between axial and bending strength has been studied experimentally and theoretically and a relationship has been established. Formulae are proposed for calculating the ultimate axial strengths of welded T-joints and the ultimate bending strengths of welded T-joints. Numerical analysis of the experimental test results has been carried out using regression methods. A computer program has been developed to facilitate this task. Design equations have been deduced as a result of the regression analysis. A theoretical study of T-joint stress distribution under axial and bending loads has been carried out using an elastic finite element system called LUSAS, which has been developed at Imperial College, London by Dr. P. Lyons. Results have been plotted using programs developed at Kingston Polytechnic. A review of the twenty existing methods for calculating the ultimate static strengths of welded T, Y. X, K and N-joints in circular hollow steel sections has also been carried out. Calculated loads have been compared with 450 existing test loads, and the results have been analysed statistically. Each formula has been reviewed and discussed and, as a result of the statistical analysis, recommendations for design formulae for K, N and X-joints have been made.

No description available.

This research explores the relationship between the configurations that international construction majors (ICMs) adopt and the effectiveness with which they develop their core competencies. Its significance lies with the fact that - due to the project-based, diversified and internationalized nature of ICMs - findings from this research not only contribute to our knowledge regarding the strategic management of large construction organizations, but also to our knowledge regarding the management of project-based organizations (PBOs) in general, and production-oriented multi-national corporations (MNCs). In addition, it expands the boundaries of core competence theory’s application towards a novel context, other than the production-oriented industries in which it has been traditionally examined. In this research, theory was critically reviewed to define and describe core competencies within the context of multi business unit (BU) organizations - such as ICMs. Drawing from ‘cybernetics’, ‘management control’ and mainstream strategic management theories, five corporate-level activities were brought forward as effectively shaping core competence development. Implementing a qualitative multiple case study strategy in the tradition of critical realism, four ICMs - and one shadow case which was ultimately not included - were studied through collection and analysis of documentary and semi-structured interview data. Their cross-case comparison - and discussion of findings in light of the extant literature - showed that the divisionalization inherent in diversified configurations can influence negatively the effectiveness with which ICMs develop their core competencies. In contrast, in the presence of ‘lateral links’ between distinct, yet related, BUs: i) standardization of processes (particularly regarding project-team integration and organizational learning mechanisms integrated with reporting processes), ii) standardization of skills and iii) standardization of norms, positively influence the effectiveness with which core competencies are developed. In addition - and perhaps most importantly - particular ‘structural’ and ‘functioning’ organizational characteristics were identified, which enable core competencies to effectively emerge.

Improving project performance by means of ensuring successful management, development and delivery of Information Technology / Information System (IT/IS) projects remains the top priority of most organisations and project communities. As a way of addressing this, Project Management Methodologies (PMMs) are regularly employed with the aim of increasing project efficiency and effectiveness. Public and private sector organisations worldwide invest significant resources into efforts ranging from a review and tailoring of the current practices to the adoption or development of a new PMM. However, despite these efforts, the contribution of these methodologies towards improving project performance and increasing successful delivery of IT/IS projects has rarely been examined or articulated. With a plentiful variety of PMMs and approaches (Traditional, Structured, and Agile) promoted as „must have‟ and „must do‟, each claiming to be “the way to success” there is limited empirically underpinned research fathoming the role which PMMs play towards successful management of IT/IS projects. The aim of this research is therefore to gain a deeper understanding of the selection and usage of PMMs in practice. This study looks beyond evaluating PMMs purely based on their traits and characteristics and investigates PMMs in their operational context: where PMMs originate from, how they support practitioners and why their implementation can cause difficulties that impact on project management, and hence ultimately influence performance in ways that can support or jeopardise project success. Through first-hand investigation of PMMs in use in their business context this study obtains a firm grasp of how PMMs ultimately facilitate or impede IT/IS project management. The research paradigm is phenomenological with the purpose of study being exploratory. An inductive approach and reasoning is employed given the scarcity of other research on this complex subject. No pre-conceived hypothesis or conceptual models were used although the research questions were validated and fully informed by the existing literature. The investigation, data organisation and data analysis were organised around the research questions. The research strategy employed is that of a multiple case study approach focusing on PMMs as the unit of investigation. Four case studies spanning disciplines, project contexts and types of PMM provide anchorage into front-line management of IT/IS projects. Case One focused on PRINCE2, a widely used structured PMM. Case Two concerned an in-house structured PMM. Case Three employed a gate-phased PMM. Case Four hosted a gate-phased PMM in the process of being phased out and replaced by agile approaches. Data was collected through semi-structured interviews. Practitioners were interviewed (48), each being in different roles with varied levels of accountability in design, development and management of projects. Some of these practitioners were key decision makers of PMM development and application. The collected data was qualitative. A combination of interpretative and content analysis was employed using a general inductive approach for qualitative data analysis. A transparent step-by-step approach to data organisation and categorisation was established. The data analysis was strongly informed by the existing research and literature. All these steps sustained the dependability and conformability of research with the research methodology and against the literature background. Overall, this research demonstrates that top-down selection and implementation of PMMs leads to four primary findings, which contribute to our understanding of the role of PMMs in the management of IT/IS projects. 1) Type-agnostic, context-free application of PMMs occurs with insufficient consideration given to IT/IS specific traits and characteristics, which in turn impedes management of projects. 2) Misalignment arises between the intended benefit of PMMs at the strategic level and the reported benefits by project managers at the project level. Additionally practitioners‟ expertise, accountability and attitude all have a direct influence on the extent to which PMMs contribute and benefit management of projects. 3) Reliance is placed on project managers to tailor the PMMs at the project level. Subsequently, informal tailoring at the project level often results in their inconsistent application. 4) In the case studies examined the organisations‟ definition of project success was predominantly efficiency-oriented (time and cost) underplaying effectiveness and business benefit. Hence the definition of project success shapes the selection and usage of PMMs. Findings 2 and 3 are new and original contributions to knowledge, whilst findings 1 and 4 provide further empirical evidence in extending our understanding of this subject.

The use of de-icing salts such as sodium chloride and calcium chloride on concrete surfaces has promoted a considerable amount of research interest. Despite the extensive amount of literature covering the wide ranges of investigations on the strength characteristics of cement paste and concrete subjected to chloride environments, very little has been published regarding such investigations with sodium chloride when present in different extreme environmental conditions, although sodium chloride is most widely used as a de-icing chemical. In this thesis the effects of alternate freeze/thaw and wet/dry cycles in presence of sodium chloride solutions of different concentrations on the strength and microstructure of hardened portland cement pastes of varying maturity have been investigated. Microstructural changes were detected by scanning electron microscopy, x-ray spectrometry, mercury intrusion porosimetry and differential thermal analysis. Attempts have been made to relate the observed microstructural features and their subsequent effects to the strength behaviour of the paste specimens. Ordinary portland cement paste specimens of 0.3 and 0.4 water/cement ratios were fixed for the investigations. The freeze/thaw cycles alternated between 0°C and -18°C. The effects of freeze/thaw and wet/dry cycles in different sodium chloride solutions on the strength of mortar specimens of different sand/cement ratios and water/cement ratios were also studied in comparison with the effects already observed in the paste specimens. It was noticed that cement paste of both 0.3 and 0.4 water/cement ratios cured normally for 3 and 7 days before being subjected to freeze/thaw cycles in different salt solutions suffered loss of compressive as well as flexural strengths that was not completely recoverable even after prolonged subsequent normal curing. The loss in flexural strength was more than that in compressive strength and freeze/thaw cycles in saturated solution caused maximum deterioration in strengths whereas 4% solution caused minimum. Wet/dry cycles in the solutions also caused loss of strengths in the specimens but their effects were less severe than that of freeze/thaw cycles. Comparison with similar tests on mortar specimens showed that mortar specimens were more resistant than paste specimens to freeze/thaw or wet/dry cycles in the solutions of sodium chloride. Examination of the fracture surfaces of cement paste by scanning electron microscopy and x-ray spectrometry, and the study of the hydration characteristics by differential thermal analysis revealed that freeze/thaw cycles in the presence of sodium chloride solutions changed the morphology of cement pastes. Calcium chloroaluminates or calcium chlorosulphoaluminates formed and their needle like crystalline structures grew more with the increase in the concentration of the solution and increase of freeze/thaw cycles. Mercury intrusion porosimetry proved to be a sensitive technique for studying the development of hydration and the changes were induced by freeze/thaw and wet/dry cycles in the solutions of sodium chloride. The freeze/thaw cycles in different solutions resulted in redistribution of pores. The possibility of improving the cement paste to withstand freeze/thaw cycles in presence of different solutions of sodium chloride using air entraining agent was investigated. Air entrained paste specimens showed clear evidence of changes in microstructure as revealed by the scanning electron microscopy and was also found to resist freeze/thaw cycles in the solutions more effectively than the specimen without an air entraining agent. The electron micrographs of air entrained specimens also provided evidence to support the suggestion that tiny air bubbles served as escape reservoirs for the movement of solution from the capillaries during freezing cycles. Finally several suggestions were put forward to enable this line of investigation to be extended to include other aspects of concrete deterioration.