In the AEC (Architecture / Engineering / Construction) industry, large construction projects are tackled by consortia of companies and individuals, who work collaboratively for the duration of the project. The consortia include design teams, product suppliers, contractors and inspection teams who must collaborate and conform to predefined scheduling constraints and standards. These projects are unique, complex and involve many participants from a number of organisations. Construction projects require consortia to procure supplies such as building materials and furniture from product suppliers. In large AEC projects, procurement of products, services and construction materials is an important and time consuming activity. Materials are sourced on a global basis from a large number of suppliers. The scale of the purchases made in large projects show that their procurement is a non-trivial exercise. Therefore, consortia members or the contractors require access to a large body of information about products or material information to aid procurement decision making. Web based communication and network technologies play an increasingly important role in supporting collaboration in AEC projects. However collaborative working in the construction industry is still restricted by the current limitations of network and communication technologies and their system architectures which are usually client/server based. The construction industry has been examining how the advancements in distributed computing technologies such as the Grid computing can remove some of the existing limitations and enhance collaboration. This research investigated how the procurement challenges such as accessing up-to-date product information available from a large number of products suppliers in an integrated manner using standard means could be addressed. A novel solution to the procurement challenges in the form of a distributed information sharing architecture is presented. The architecture uses the concepts of federated databases such as distribution of data and autonomy of databases and couples it with Grid computing to facilitate information exchange in a collaborative, coherent and integrated way to address the product procurement challenges.

No description available.

This thesis deals with the potential contribution that state-of-the-art solar thermal (ST) systems enhanced by thermal energy storage (TES) technologies might have in reducing the energy use in Welsh dwellings. The focus of this work lies with the share of the overall amount of conventional energy currently consumed for thermal comfort and hot water preparation that could be replaced by solar energy harvested by active, water-based, solar systems. Twelve typical Welsh dwellings drawn from a recent survey and considered as representative of the Welsh housing stock are modelled and the solar collectors' yield for different orientations and tilts is predicted. The subject is investigated with computer simulations using the TRNSYS simulation engine. The methodology dictates at first prediction and analysis of the thermal energy demand profiles of 12x4 case studies using average (smoothed) and actual (warmer) weather conditions, continuous and intermittent comfort maintenance. Next the ST potential is estimated considering solely a maximum (0.7) and an average (0.4) overall system efficiency and no other technical part for the ST system (modelling approach), in order to investigate the mismatch of energy demand and availability and the TES contribution. The performance characteristics of some representative European ST systems (short-term TES only), as derived from the IEA SHC Task 26 FSC method, are then applied to the simulations to reveal the potential with realistic losses and parasitic energy consumption included (applied only to 5 compatible models). It is revealed that all these house types are possible candidates for effective ST applications, assuming that economies of scale would allow for large absorber areas in the near future. The modelling approach shows that ST systems could contribute to thermal savings between 9%-34% solely with direct utilisation of the collected energy. Furthermore, for most cases, if reasonable sized stores would be used (up to 300kWh TES capacity) then the solar contribution to the overall thermal energy consumption, in the most favourable conditions, would be around 42-58%. Only a couple of models appear to have a lower potential, mainly due to lack of sufficient absorber areas. However for reaching the highest end of expectations for certain house types---up to 54% with average and up to 100% with warmer weather conditions---inter-seasonal storage would be required. In this case, the justifiable storage capacities predicted correspond to very large store volumes, revealing that these are currently not feasible options, as sensible heat storage is still the state-of-the-art for TES. Use of innovative storage types identified by the literature survey, that would only be available in the future, are required in order to achieve high solar contributions, considering space limitations in Welsh dwellings. The FSC results show that for the 5 models the use of solar energy would bring thermal energy savings of around 41-47% if the best system is employed compared to a conventional system, while if parasitic (electric) energy consumption is considered the expected energy savings could be as low as 10%. The actual ST potential is analysed and is found to be in between the two approaches, as both methods have advantages and limitations and complement each other.

No description available.

This thesis sets out to identify and define a set of criteria by which building materials and elements can be assessed in terms of forming part of closed loop material cycle, and from which legally binding targets can be developed to support good practice in relation to sustainable material design in the built environment. An initial investigation into the research context of sustainability applied to the built environment and the means of implementing good practice in the building industry is followed by a review of selected sustainable material design philosophies. Based on a synthesis of these philosophies and how they can be applied to building practice, the dissertation proposes a concept for a comprehensive approach to sustainable material design that incorporates a requirement for close loop material cycle construction. The characteristics of closed loop material cycles and their relevance to the building industry are considered, and a set of criteria for closed loop material cycle construction is formulated, drawing on existing research and guidance on natural recovery and design for deconstruction and recycling. The criteria are applied in a pilot assessment of selected materials, building elements and three whole house designs, which suggests that closed loop material cycle construction is technically feasible. The assessment results are used to suggest possible practical good practice targets for closed loop material cycle construction content that are achievable for mainstream housing construction and that can bring significant benefits in terms of improving the sustainability of construction developments. The dissertation concludes with a critical reflection on the conceptual development and practical application of the closed loop material cycle criteria and proposes an agenda for further research in this field.

This thesis describes a series of investigations performed to determine the possibility of separating bricks and mortar using pressure waves. A study of the current brick recycling practised within the UK was performed. This study identifies a need for improved brick reclamation processes. Initial investigations were performed using one-sixth scale couplets. The one-sixth scale bricks and mortar could be separated by placing them in an ultrasound bath. Further investigations were performed to determine the vibrations that would be necessary to recreate the separation of one-sixth scale couplet using an ultrasound bath at full scale. Based on these investigations, a prototype designed to separate full scale couplets was constructed. A series of specimens were tested in the prototype and the vibrations passing through the specimens were recorded. These results showed that the prototype was able to achieve vibrations at the intended frequency and amplitude within the specimens. However, no separation occurred and therefore it was concluded that this process was not appropriate for brick reclamation of full scale bricks in this manner. An investigation of the bond strength developed between the bricks and mortar of one-sixth scale and full scale couplets was performed. It was found that the full scale specimens developed a bond strength greater than that developed in the one-sixth scale specimens.

No description available.

This thesis presents two global analysis approaches to the calculation of the natural frequencies of high rise buildings. The structures are proportional and their component members are repeated at each storey level unless there is a step change of properties. Within this scope many geometric configurations can be encompassed, ranging from uniform structures with doubly symmetric floor plans to doubly asymmetric ones comprising plane frame and wall structures running in two orthogonal directions. The first method utilises a continuum element approach in which the structure is divided into segments by cutting through the structure horizontally at those storey levels corresponding to changes in storey properties. A typical segment is then replaced by an appropriate substitute beam that has uniformly distributed mass and stiffness. Subsequently, the governing differential equations of the substitute beam are formulated using the continuum approach and posed in the form of a dynamic member stiffness matrix that is exact to small deflection theory. Since the formulation allows for the distributed mass and stiffness of the member, it necessitates the solution of a transcendental eigenvalue problem. The required natural frequencies are thus determined using a cantilever model in conjunction with the Wittrick-Williams algorithm, which ensures that no natural frequencies can be missed. In addition, a two step process has been developed for certain asymmetric structures in which the natural frequencies corresponding to coupled motion between the planes of vibration can be obtained from the equivalent uncoupled ones through a simple cubic relationship. This enables coupled, three-dimensional vibration problems to be solved very efficiently using a two dimensional approach. The second method utilises the Principle of Multiples which, when applicable, enables any frame, regardless of the number of storeys or bays, to be simplified to an equivalent one bay frame, that has precisely the same natural frequencies. If the original frame does not fully satisfy the Principle, the same process can still be utilised, but the resulting substitute frame will yield approximate frequencies, although they will normally be acceptable to engineering accuracy. Like the first method, it can also be used for the vibration analysis of asymmetric, three-dimensional frame and wall-frame structures in a two-step procedure. First the analogous uncoupled system is analysed using substitute frames, then the relationship between the uncoupled and coupled responses is imposed through a cubic equation. Both of the above methods assume rigid floor diaphragms and require a knowledge of the building's static eccentricity at each storey level. The current methods of calculating this are cumbersome and even the definitions are open to dispute. A practical method of calculation is therefore presented and a small parametric study enables recommendations to be made. Overall, the proposed methods require little effort, offer clear and concise output and can sometimes yield solutions of sufficient accuracy for definitive checks, but more usually provide engineering accuracy for intermediate checks during tasks such as scheme development or remedial work. This claim is supported by the results of extensive parametric studies undertaken for this thesis. In all examples, the results from the proposed methods have been compared with the results of a full finite element analysis of the original structure obtained using the vibration programme ETABS. The exercise confirms that the proposed methods can yield results of sufficient accuracy for engineering calculations.

This thesis investigates the thermal effect of green roofs and green walls on the built environment and investigates whether they could be used in existing cities so as mitigate the heat island effect. In order to estimate this for various climates, a prognostic, micro-scale, two-dimensional heat and mass transfer model has been developed. In the first chapter the aim, objectives and methodology of the research are established. In the second chapter a literature review of the causes and the consequences of the heat island effect is made, as well as a critique on the use of urban parks for mitigating raised urban temperatures. In the third chapter, a research is carried out where, when and why roofs and walls were covered with vegetation. In the fourth chapter the development of the one-dimensional model is presented, for heat and mass transfer in building materials, a soils, plants and the air. The model is validated with an experiment conducted at a concrete and a vegetated test cell. A comparison is made between green roofs and conventional concrete ones, as well as with white coated roofs for different climates. In the fifth chapter the one-dimensional model is developed into a two-dimensional one and the microclimatic heat and mass transfer model of a typical urban canyon is established. In the sixth chapter, the model is used to investigate the effect of green roofs and green walls for various climates, geometries, canyon orientations and wind directions. From this parametric analysis, an investigation is done on how the raised urban temperatures could lower when the building envelope is covered with vegetation, which could lead to energy savings for cooling and more comfortable outdoor conditions. In the last chapter, conclusions are drawn from the results of this thesis and further research is proposed.

A programme of masonry tests has been undertaken at prototype and model scales with a view to comparing their behaviour and strength under various conditions of loading. Characterisation tests were carried out to determine the principal behaviour of the units and mortar before the main programme of masonry test. The testing regime was in two parts: in the first category of tests compressive, shear, flexural, bond and diagonal tensile strength tests were carried out on prototype, half, fourth and sixth scale models. While in the second category of tests the effect of different joint thickness, increasing mortar strength and different sand gradings were tested on the compressive, shear, flexural, bond and diagonal tensile strengths of sixth scale model masonry. The size effect laws for quasi-brittle materials from fracture mechanics were also applied to the test data in order to find out their suitability to masonry model studies. The knowledge gained on the model scale behaviour of masonry was then applied to a prototype study involving the effect of eccentricity on the compressive strength of masonry as it relates to masonry arches. The sixth model scale was used for this study using four different eccentricities. On the whole, the model tests showed similar behaviour to the prototype. While there was no discernable scale effect in the shear, flexural, bond and diagonal tensile strength test, the compressive strength tests showed a noticeable scale effect. The parametric study at sixth scale also showed it is possible to use a sixth model to determine the effect of the increasing mortar strength and different grading of sands on masonry strength. However, the effect of increasing joint thickness was difficult to quantify. Indications from the size effect analysis of test data were also encouraging. The experimental data from the different tests were generally found to be in good agreement with the size effect laws of fracture mechanics. The application study was found to agree with the prototype investigation for low eccentricities but does not correspond well for higher eccentricities. Overall the results showed that it was possible to use model tests to provide masonry strength properties that could be used to determine the structural behaviour real life structures from numerical studies.