The recycling of demolished masonry rubble as the coarse aggregate in new concrete represents an interesting possibility at a time when the cost of dumping such material is on the increase. With growing concerns over the environmental impact of aggregate extraction and the continued rise in aggregate demand in the UK, it is clear that the market is now there for recycled and secondary aggregates. The present investigation consists of experimental and theoretical studies into the effects of using recycled aggregates to produce concrete instead of virgin aggregates. The aggregates used have been recycled from construction and demolition waste. The recycled aggregates were predominately made up of crushed bricks but the aggregates did contain impurities such as timber and mortar. New bricks were crushed to form an aggregate in order to investigate the properties of brick as a material without impurities. The physical properties of the various aggregates were firstly examined and compared with granite aggregate, an aggregate proven in the production of good quality concrete. Concrete was then produced with the aggregates and all the physical and mechanical properties of the concretes were examined in some detail. The results showed that recycled masonry aggregates can be used successfully to produce· concrete of an acceptable standard. New test methods were presented in this investigation to determine brick porosity and water absorption. This involved the testing of broken brick fragments under vacuum, rather than the testing of whole brick units by 5hrs boiling or 24hrs submersion in cold water. The new test methods proved to be easy to perform and provided accurate results. A new test method for estimating the strength of bricks was presented. This involved point-loading of masonry specimens to obtain strength index values. From the pointload results, equations were presented relating the strength index values of brick fragments to the compressive strength of whole brick units. This involved the development of shape factors for different masonry specimens. The point-load test is easy to perform, presents a cheaper alternative to heavy compression machines and can be used on site to determine the suitability of recycled bricks as the aggregate in new concrete.

The need for improved timber grading is key to improving Scottish forestry: the majority (80%) of the sustainable softwood population in Scotland is Sitka spruce of variable quality. Current visual assessment of strength and stiffness is inaccurate, and machine stress grading in sawmills is little better due to incorrect assumptions regarding consistency within softwood species and between trees of the same stand. The author develops and evaluates non-destructive test (NOT) methods for Scottish Sitka spruce based upon impact-e9ho testing across a range of scales from plank, to log, to standing tree. Correlations between harmonic wave propagation velocity and elastic modulus of 0.62 ::; R2 ::; 0.71 were possible in Sitka spruce under a range of conditions including: genotype progeny, variable height and radial position in stem, and variable knot content. In achieving this correlation, the research also investigated acoustic parameters such as: time of flight velocity, damping ratio, and resonant peak behaviour with regard to their influence on dynamically derived moduli of elasticity. Examination of variation in wood properties (including static elastic modulus, knot content, simulated decay, density, and grain alignment) on these acoustic parameters was conducted on semi-controlled specimens of differing homogeneities. The consequences of these results should influence the development of timber NOT tools. In addition to the development of an NOT method, the author has provided the first large-scale derivation of reference values for dynamic stiffness and other acoustic properties for 35 year old logs and beams of Sitka spruce in Scotland.

Water ingress, usually by wind-driven rain, is the main cause of premature deterioration in masonry structures. Water acts as a transport mechanism for aggressive chemicals and can also undergo freeze/thaw cycles leading to bursting of the masonry microstructure. Factors such as the absorption rates of brick, water/cement ratio of the mortar, workmanship of the mason and poor design detail have all been identified as influencing the amount of water likely to penetrate a structure. It is also recognized that the majority of water ingress occurs at the brick unit/mortar joint interface, where interstices are present that allow access to the masonry interior. The size, extent and influence that the brick/mortar interface has in governing water ingress is likely to be controlled by both the applied stress level and bed orientation of the main mortar beds relative to the direction of loading. Very little research has investigated these parameters in detail. By using a new ingress measurement technique, the effect of the applied stress level and bed orientation was quantified. The main mortar beds of concentrically loaded masonry panels were found to deteriorate in their resistance to water ingress as they were orientated from perpendicular to parallel relative to the direction of loading. Poisson's ratio effects, which generated differential expansion between brick and mortar were believed to control water ingress at mortarjoints orthogonal to the main beds. Water ingress at these mortarjoints was also found greatly influenced by both applied stress level and bed orientation. Factors such as the applied pressure head of water impinging onto the panel, the variability of the brick type used, eccentricity of applied loads and the pre-wetting of panels were also found to have some controlling influence on the water ingress characteristics of masonry. Empirical modelling of water ingress dependent upon time, stress level, bed orientation and pressure head of water, was also undertaken. This enabled the volume of water ingress to be mathematically generated, with these models exhibiting good agreement with experimental data. Suggestions for future work include assessing the effect of higher applied stress levels on water ingress, verification of the laboratory work with on-site tests and the introduction of freeze/thaw testing on loaded panels to simulate an abrasive external environment. Numerical analysis using finite element modelling was also identified.

Direct electric curing is the method by which the hydration reactions within concrete are thermally accelerated by passing an alternating electric current through the sample. This use of electricity as a means of supplying heat to young concrete and mortar has become recognised as a more effective and energy efficient form of accelerating the curing process than traditional steam curing. The present investigation involves studying the affects of thermally accelerated curing of cementitious materials in comparison to normally non-heated curing. Prior to mixing, tests are performed on the constituents of the cementitious mixes. Results of these tests are used in the creation of mix designs for mortar and concrete samples. A range of concrete mixes are designed with and without additives and admixtures are used to make cubes, slabs and beams. From the testing results, the factors affecting the short and long term properties of electrically cured cementitious materials are investigated and heating regimes are presented to achieve specific properties of both strength and durability at specific ages. A substantial section of reinforced concrete is required to gain representative results in electrically curing reinforced concrete slabs. Compressive strength is difficult to measure due to the electrical distortion affects of inserts and the damage caused by coring so that at present, basic maturity concepts are used as a compressive strength guide which limits the validity of results obtained. This research looks at refining these concepts to include early age heating effects induced by direct electric curing. The microstructural development of concrete when subjected to accelerated curing is also considered. The affect of delay periods and maximum temperature is studied using a scanning electron microscope and the results presented.

The engineering design process is an iterative and distributed process. It is often characterized by multi-disciplinary teams in multiple places working together, on a single project, using different models and software tools. The current collaboration approaches in AEC industry often focus on integrating and managing multiple models from multi-designers. Building Information Modelling (BIM) is playing a major role in facilitating collaboration. BIM provides an opportunity to electronically model and manage the vast amount of information embedded in a building project, from conception to completion. In the design process, changes in the models are inevitable and very common. They can occur at any stage of the project, from different sources, and for various reasons, which can have significant effects on the process. Versioning is a solution for design change management. Many model versions can be created and distributed among the disciplinary teams. Despite many researches done on the subject and the availability of some software applications that deal with changes in design, the mechanism to cope with the changes among different model versions needs further studies to increase the management efficiencies and ensure designers have an up-to-date version of the model. The challenges of information exchange in project management result from: a combination of the enormous amounts of information generated, the large variety of design systems involved, and data format utilised by different disciplines at various design stages. The Industry Foundation Classes (IFC) standard represents a paradigm shift for data and information exchange. The main goal for developing the IFC model is to provide a neutral data format to exchange information among different software programs. IFC models reflect the current state of BIM model. They do not take into consideration the process and results of latest changes among different BIM users nor record the history of earlier changes. This research work therefore investigates how to improve the process of managing the design changes from different disciplinary models. This research developed a collaborative methodology to manage the design changes in different models. It tackles the challenges of the versioning process as a change management approach. This is done through extending the capability of the existing IFC schema to control and manage different design changes in different BIM models. The proposed extended IFC incorporates the changed information of the latest model version and provides the complete history of changes of all earlier model versions. A prototype system was developed in this research to implement and validate the extended IFC and to demonstrate using it to improve the management of the whole design process. The research process involved undertaking a literature review to identify knowledge gaps and challenges in the areas of the (design process, BIM, IFC, and change management). The research also investigated and analysed the IFC standard and identified two key requirements of extending the IFC and implementing the prototype. Further aspects of this research include developing a framework to facilitate a collaborative design, extending the existing IFC schema, designing and implementing the prototype based on the extension, and validating and evaluating the extended IFC and the prototype system. The research concludes that the extended IFC to handle versioning can effectively improve collaborative design. It addressed concepts involving comparing, storing, classifying, extending managing, versioning, exchanging, and sharing of modelling information in a collaborative way. The proposed process of managing design changes covered an important gap associated with current IFC models, which can be incorporated in future releases of the IFC standard.

Mitigation of progressive collapse after an initial failure has become a primary concern of engineers in recent years. Often alternative load paths are sought to redistribute load from the damaged area. It has been recognised for some time that the omission of compressive membrane action (CMA), also termed ‘arching action’, can lead to a significant underestimation of load capacity. An investigation has been conducted to ascertain whether the additional load carrying capacity from CMA can provide an inherent alternative load path to aid robustness. A series of scaled specimens with industry standard detailing have been designed for an experimental investigation. Reinforced concrete elements were modelled in the double span scenario once an intermediate column has been removed. The test rig used allows the central support to be removed followed by the application of a point load applied at midspan; the system is determinate including measurement of the horizontal reaction. Subsequent to the flexural response two modes of membrane action are induced, initially compressive until tensile membrane extends load capacity at high values of deflection. The response during the latter tensile phase is outside the scope of this research. Comparisons of experimental data with analytical methods inclusive of CMA have demonstrated that whilst conservative the method by Merola (2009) provides a reasonable prediction. This method has been utilised in a study of a series of flat slab structures with a range of column spacings. The inherent restraint stiffness provided by the surrounding slab and frame has been quantified using FEA and has allowed for the extent to which CMA can improve the robustness of a structure to be determined.

Pile heat exchangers are expected to make a significant contribution to meeting UK and EU renewable energy and carbon dioxide reduction targets. However, design for the thermal capacity of pile heat exchangers has to date been largely based on methods developed for borehole heat exchangers. Piles have a much smaller aspect (length to diameter) ratio than boreholes and consequently their thermal behaviour is different in a number of important ways. This thesis explores these differences and makes recommendations for improved assessment of pile heat exchanger thermal capacity. Traditionally vertical heat exchanger design assumes separation of the thermal effects in the ground and in the pile. A transient temperature response function is used to assess temperature changes in the ground and a steady state resistance is applied to the pile concrete. In this thesis existing approaches to temperature response functions are critically assessed for use with thermal piles. It is important to take into account the larger pile diameter, which causes increased temperature changes in the short term. In the long term, the shorter pile length will result in reduced temperature changes as steady state is reached more quickly. Simple 2D numerical modelling has been carried out and the results used to derive a new method for determining pile thermal resistance. However, for large diameter piles, the time taken for the pile to reach steady state suggests that the use of a constant thermal resistance in design is not always appropriate. In these cases it is recommended that a transient temperature response function is used to assess the response of the ground and the concrete together. The applicability of short duration thermal response testing for pile heat exchangers has been examined. Modelling and case study data has shown that the technique is only reliable for piles of 300mm diameter or less. For the special case of large diameter piles with centrally placed heat transfer pipes then it is possible to use the test to determine the thermal conductivity of the pile concrete, but not pile thermal resistance.

Modern office buildings are often open plan buildings with a frame consisting of flat RC slabs, RC columns and non-load bearing internal and external partitions and facades. These modern framed structures are more flexible than older conventional buildings with load bearing walls and are less susceptible to differential settlement damage. The use of conventional guidelines for differential settlement on modern flexible framed structures may therefore be over-conservative. The literature review of the study highlights the factors producing differential settlement, the types of damage caused by differential settlement and conventional guidelines for limiting differential settlement damage. Conventional guidelines focusing on 2D structures lack provision for the 3D deformation of a structure. To determine the behaviour of a modern flexible framed structure a numerical experiment was performed, which consisted of the design according to British Standards and Eurocodes of a 3D, 5-bay by 5-bay, 6 storey flat slab RC frame with pad foundations on clay. The behaviour of the designed structure undergoing differential settlement was then analysed by means of linear-elastic finite element analyses. The results show firstly that it is possible to normalise structural behaviour to the soilstructure stiffness ratio, secondly the importance of 3D deformation of the structure and thirdly that stiffer load-displacement responses of foundations may also affect the behaviour of the structure. A stiffer load-displacement response may occur with the reuse of foundations

The primary aim of the project was to develop the basis for a set of rules to be used in the design of RHS slim floor edge beams with web openings. However, since the research is fundamental in nature, the findings are also applicable to other situations where it may be advantageous to cut holes in load bearing tubular members of rectangular cross-section. The study considered the influence of the number and size of holes upon resistance and stiffness in bending, shear, and torsion and combined analytical Finite Element modelling with large and small scale pseudo-static (short-time static loading) laboratory testing. In all but one category of tests (see below), good agreement was achieved between experimentally measured quantities (such as capacities, deflections and strains) and the corresponding Finite Element predictions, allowing parametric investigations to be conducted with calibrated analytical models. Preliminary design recommendations are presented based on the results of the parametric study and laboratory tests. The design advice was developed with regard to existing recommendations for the design of perforated I-beams, and was produced in a form that allows integration with modern limit state design codes. Aspects of behaviour requiring further investigation have been identified and categorised. Torsion tests on full scale RHS without web openings yielded some unexpected results. Elastic and plastic capacities measured in the laboratory were significantly lower (12–20%) than those predicted by the Finite Element models and the thick walled torsion theory used as the basis of the British and European design procedures. Attempts were made to determine the cause of this behaviour and a number of possibilities were eliminated. Although the anomalous results have not been fully explained, evidence of similar behaviour in previous full-scale testing was discovered.

Good building design can provide a myriad of benefits. There is ample evidence suggesting an association between design attributes and various outcomes for users and other stakeholders of built environments. Despite is importance, design quality is found to be overlooked in building projects in favour of other objectives such as time and cost. Recent initiatives have attempted to highlight the value of design quality, however, their focus have been mainly on post project completion and building evaluation. ‘How’ design quality - with its complex nature –is achieved during the projects has seen little empirical attempt. The research in this thesis, therefore, aimed to improve the understanding of design quality achievement in building projects by exploring the critical success factors (CSFs) and stakeholder attributes. A multi-phase, mixed methods approach was developed to fulfil this aim. In the first phase, the theory and methods offered in ‘project success’ and ‘stakeholder management’ assisted in devising a developmental process to a) identify, validate and evaluate the CSFs, and to b) explore stakeholder attributes using three major analysis models. A preliminary interview study, then, explored the viewpoints of 11 architects on the topic and verified the research aim and directions. A matrix-based model was also used to map the bi-directionality between design quality and its stakeholders. The second phase, consisting of a qualitative study followed by a quantitative one, first identified 36 potential CSFs from the perspective of 10 experts and then validated 28 of them through a questionnaire survey of 129 individuals with architecture and client backgrounds. ‘Brief’, ‘communications’ and ‘leadership’ were revealed as the most important CSFs. Using principal Component Analysis to assess the interrelationships between the CSFs in 126 building projects extracted 7 components that could meaningfully represent the CSFs. Moreover, Regression Analysis was employed to establish the causal relationship between these components and the design quality success criteria of functionality, build quality and impact. It was found that the components collectively contribute to the achievement of design quality in real projects but differently to each of its success criteria. Also, by applying the second stakeholder model, it was found that clients and architects had the highest level of power, proximity and urgency with regard to design quality decisions while users and facility managers were low in these attributes. In phase 3, Social Network Analysis was used to model and visualise the stakeholder relationships with regard to design quality in a case project (third stakeholder model). 21 members of the stakeholder groups were approached and their involvement, influence and communication effectiveness were assessed. Apart from the evolving understanding obtained through the above process, the research contributed by developing conceptual frameworks for a) design quality CSFs, b) design quality related stakeholder relationships, and c) success criteria of building projects. Moreover, for the first time, the dynamism of stakeholder communications in a construction project was visualised for different stages. Based on the knowledge emerged, the research also proposed a holistic evaluation of design quality achievement to enhance the current DQI tool.