The search to find new ways of improving performance in the construction industry led to the introduction of collaborative working and, after fifteen years the question is has this approach delivered the expected improvements. The management of collaborative relationships is often underpinned by trust as a governance mechanism. However, owing to the practical problems of operating in the public sector combined, with the natural disposition of human behavior, the risk of opportunism and exploitation remains, requiring additional governance mechanisms to be put in place. However these mechanisms can only be realised if there is a position of strong buyer power. Therefore, the purpose of this thesis is to consider what impact buyer / supplier power has on collaboration and the consequent benefits delivered. Research has been carried out on a case study involving four projects from the Birmingham Construction Partnership using interviews and a questionnaire. It was found that levels of collaboration were not affected by marginal differences in power, but rather by agency factors and trust. However, the conclusion drawn is that the buyer must retain a strong position of power in order to ensure the buyer obtains a good apportionment of value generated by collaboration.

The United Kingdom published a legally binding document to reduce national greenhouse gas emissions by year 2020 up to 34% against the 1990 levels. This target also fulfils the Europe 2020 strategy of 20% carbon emission reductions by year 2020 (EC, 2010). Emissions due to space heating count for around 60% of the total domestic emissions (DCLG, 2012). The report “Rethinking Construction” published in 1998 emphasised the opportunities to improve the quality and efficiency of the UK construction sector (Egan, 1998). More recently, a framework has been published by the Government to tackle fuel poverty by building more energy efficient homes (DECC, 2015). In terms of energy performance, Passivhaus is recognised as one of the most energy efficient and researched construction standards which requires an exceptionally high-level of insulation and airtightness. Closed-panel timber frames are a relatively new system in UK with an opportunity for growth. These advanced panels are pre-fitted in the factory, reducing the on-site work. However, closed-panel systems present a more complex sole plate fixing detail which can have an undesirable long-term impact on the structural and thermal performance of the building. The work presented in this thesis investigates the structural considerations, racking performance, of timber frame closed panel systems for future building regulations. The thesis underlines the significance of structural stability, serviceability and detailing in relationship with long-term thermal efficiency and airtightness, according to Passivhaus standard. An experimental study was carried out to investigate the structural racking performance of advanced closed panel systems. A comparison was made between the behaviour of the timber frame panels and the analytical PD 6693-1. A set of different wall panel built-ups is presented for optimised Passivhaus design, including thermal bridge-free sole plate details. A timber frame racking software application was developed to optimise the structural design of shear walls. A parametric study was carried out with this tool to generate efficient timber frame wall design tables for different applied racking loads and U-values. The software application also allows for direct specification of robust sole plate base fixings and thermal bridge free details.

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Flat plate systems are constructed with slabs directly supported on columns. Since there are no beams in the system, the behavior of connections between the slabs and columns play a crucial role. Due to the sudden and brittle nature of punching shear failures, slab-column connection design must be conducted with proper safety precautions. The first part of this study aims to evaluate the safety level of different design expressions in the codes. Fir this purpose, the ability of ACI 318-11, TS-500 and Eurocode-2 to estimate punching shear strength was examined in light of experimental results compiled from previous research. Interior and exterior connections were examined in the course of the study. In the second part of the study, beam and shell models were calibrated to simulate the load-deformation response of interior slab-column connections in light of experimental results. In the final part of this thesis, a typical floor plan of a flat plate system was analyzed to investigate the possibility of a progressivefailure mechanism after punching failure takes place at a slab-column connection. Minimum post-punching capacity required to avoid progressive punching failure in a floor was estimated. It is believed that, the results of this study can be helpful in guiding engineers in understanding the safety inherent in punching shear design expressions and to take necessary precautions against progressive collapse.

The compatibility properties of some contemporary finish coats together with their complementary layers used in insulated exterior walls were examined in terms of water vapour permeability and modulus of elasticity. Basic physical and mechanical properties of some synthetic-, cement- and polymer-based external finish coats were analyzed in laboratory. Some additional samples, complementing the wall section, were also examined for their water vapour permeability. Results showed that the finish coats were high vapour permeable although they had high resistance to water vapour permeation, which was achieved by their application in thin layers. Cement-based undercoats were found to be medium permeable. The application of primer and/or paint was found to decrease the permeability of finish coats in different ranges. Thermal insulation layer was found to interrupt water vapour flow considerably. Among polystyrene- and mineral-wool-based thermal insulation boards, rockwool was recommended as the insulation layer due to its medium vapour permeability. In conclusion, walls insulated externally with rockwool boards and plastered with polymer-based finish coat, FC8ACB or synthetic-based finish coat FC3SB were found to be the most proper combination in terms of breathing and thermal resistance capabilities. All finish coats seemed to have sufficient strength and except the synthetic-based finish coat, FC2SB, they seemed to be compatible with each other and with the masonry in terms of their Emod values. Further studies were recommended on some other compatibility properties of finishing systems, such as thermal and moisture dilatation properties, and on the relation between the resistance to water vapour permeation and water permeability.

This thesis offers a comprehensive risk assessment methodology that provides a decision support tool, directed for Turkish construction organizations, which can be utilized through the bidding decisions for international construction projects. Within this context the analytic network process technique is implemented to develop a risk assessment model, which is used to derive the relative priorities of the risk factors associated with international construction projects. The findings of the risk assessment model have demonstrated that the most significant sources of risk are vagueness of contract conditions about risk allocation, client, and immaturity of legal system in the host country. Factors such as low % of advance payment, geographical distance, and bribery were found to be relatively insignificant. An international construction project risk rating software application is then developed. The application incorporates the derived priorities from the risk assessment model to calculate a risk rating for a given international construction project. To increase the credibility of the results a risk rating adjustment methodology was integrated into the application. Its purpose is to count for the potential influencing factors that may increase the risk level of a given project. The influencing factors which were considered are the company&rsquo / s experience, contract type, level of the available project data from the outset, and project delivery system. The application is also structured to enhance the organizational learning practices. It improves the process of the organizational memory formation with respect to postproject risk data by developing a database of risk information of the rated projects for future references. The reliability of the application was tested with post-projects risk data and was found to be satisfactory.

One of the major change efforts for the construction industry is lean construction. This thesis analyzes the practices of the construction companies in Turkey from the lean construction perspective. Prior to the analysis in question, requisite information about change in the construction industry, lean thinking and lean construction will be presented. A questionnaire, based on a lean construction model, is used to survey the practices and gather the data for the analysis. Various statistical analysis methods are performed on the gathered data to make inferences. According to these analyses, the lean construction characteristics of the construction companies will be discussed and the recommendations for improving the lean conformance of the construction companies will be presented.

ABSTRACT EFFECTS OF POZZOLAN INCORPORATION AND CURING CONDITIONS ON STRENGTH AND WATER RESISTANCE OF NATURAL GYPSUM PASTES Cengiz, Okan Ph.D., Department of Civil Engineering Supervisor : Prof. Dr. Turhan Y. Erdogan September 2009, 189 pages There are large reserves of gypsum rock (CaSO4&middot / 2H2O) in Turkey and in various regions of the world. Heating gypsum rock to 140 - 190 0C causes it to lose three-fourths of its water molecules and turn into gypsum, called plaster of Paris / heat application over 190 0C results in loss of all the water molecules and this form of the material is called gypsum anhydrite. When gypsum is mixed with water, it gains cementitious property and hardens in a short time. Therefore, natural gypsum anhydrite and especially plaster of Paris are widely used in the construction industry. On the other hand, its not being water resistant and having low strength restrict the use of gypsum products for outdoor applications. In this study, the effects of pozzolan incorporation to natural gypsum pastes and application of various curing regimes for improving their water resistance and strength were investigated. Compressive strength and absorption tests on one thousand one hundred twenty two 5-cm cube specimens produced from v 13 different mixture types were conducted. Also the microstructures of these products were investigated using the analytical technique X-Ray Diffraction. The test results showed that water resistance and strength properties of pozzolan-incorporated gypsum products were improved. Curing of the product at elevated temperature regimes was an additional factor that contributed to this improvement. It was concluded that the natural gypsum mixtures prepared and cured at the above-mentioned conditions could also be used for outdoor applications. Keywords: Pozzolan, Natural Gypsum, Elevated Temperature Curing

Accelerating and mineral admixtures, one of the major ingredients in concrete, are primarily used to modify the properties of both fresh and hardened concrete. Within the scope of this thesis, there were four types of cements having almost identical fineness. The mixes were prepared by using natural pozzolan, blast furnace slag and limestone conforming to TS EN 197-1 and two types of accelerating admixtures, namely triethanolamine (TEA) and calcium formate (CF). The effect of set accelerating admixtures with different cement types on the setting time, water demand and compressive strength has been analyzed by an experimental study in accordance with relevant ASTM standards. Finally, it has been observed that the amount of the accelerating admixtures used is suitable because of their effects on the water demand, setting and strength. Due to the density difference of mineral admixtures and clinker, the normal consistency and 110% flow water content should be considered on a volumetric basis. The effectiveness of the accelerating admixtures on the normal consistency water, 110% flow water content and setting time depends on the type and amount of mineral admixtures. The increase caused by CF in the normal consistency and 110% flow water content is higher than that by TEA. The accelerating effect of TEA and CF on the setting times is more significant for cements incorporating 6% mineral admixture. The effects of accelerating admixtures on the compressive strength change with specimen age, type and amount of mineral admixtures. Generally, for all cement types, early age compressive strengths increase with the increase of TEA, however long term strengths increase by increasing CF.

Due to its complex nature, risk and uncertainty are more widespread in construction industry than many other industries. Aiming to ensure that all project objectives are met, risk management is considered as a critical success factor for construction projects. The core elements of risk management are now known and used by many organizations. On the other hand, as declared by Project Management Institute (PMI), the ability to measure the effectiveness in managing risk is one of the most important areas that risk management needs to be developed in. Designed to assess the capability of a project or an organization in a particular area, a maturity model aids in determining strengths and weaknesses, and to target improvement strategies accordingly. Several maturity models have been developed for the area of risk management and furthermore, an attempt to adapt a generic risk management maturity model to the construction industry was specified from the literature. All in all, when examined, it was seen that most of these models outline the topics to be investigated in a maturity assessment and provide guidance in terms of content. It was believed that a practical approach was needed and the diagnostic characteristics of these models should be enhanced. Therefore, the aim of this study was to propose a construction risk management maturity framework, together with an easily applicable and effective questionnaire. To achieve this aim, six outstanding risk management maturity models were examined, and the proposed model was further supported with construction-specific attributes such as construction supply chain issues. The applicability of the model was tested through case studies conducted with five large scale Turkish construction companies. The results were evaluated and interpreted for each company and the gathered data were further investigated through statistical tests for certain comparisons. Finally, the questionnaire was revised with respect to the feedback received from the case studies.