Integrating Building Functions into Massive External Walls

Well into the twentieth century, brick and stone were the materials used. Bricklaying and stonemasonry were the construction technologies employed for the exterior walls of virtually all major structures. However, with the rise in quality of life, the massive walls alone became incapable of fulfilling all the developed needs. Adjacent systems and layers had then to be attached to the massive layer. Nowadays, the external wall is usually composed of a layered construction. Each external wall function is usually represented by a separate layer or system. The massive layer of the wall is usually responsible for the load-bearing function. Traditional massive external walls vary in terms of their external appearance, their composition and attached layers. However, their design and construction process is usually a repeated process. It is a linear process where each discipline is concerned with a separate layer or system. These disciplines usually take their tasks away and bring them back to be re-integrated in a layered manner. New massive technologies with additional function have recently become available. Such technologies can provide the external wall with other functions in addition to its load-bearing function. The purpose of this research is to map the changes required to the traditional design and construction process when massive technologies with additional function are applied in external walls. Moreover, the research aims at assessing the performance of massive solutions with additional function when compared to traditional solutions in two different contexts, the Netherlands and Egypt. Through the analysis of different additional function technologies in external walls, a guidance scheme for different stakeholders is generated. It shows the expected process changes as related to the product level and customization level. Moreover, the research concludes that the performance of additional insulating technologies, and specifically Autoclaved Aerated Concrete can provide a better construction compared to the traditional external wall construction of the Netherlands and Egypt

Distributed parameter sensitivity analysis of laterally loaded piles in non-homogeneous soil (soft clay overlying sand under cyclic loading)

Laterally loaded piles are widely used to support many structures such as high-rise buildings, bridge abutments and offshore structures. This dissertation presents the study of the sensitivity of laterally loaded piles embedded in non-homogeneous soil consisting of soft clay overlying sand subjected to cyclic loading. The study is divided into three parts. In the first part, the theoretical formulation for the sensitivity of the pile\u27s head lateral deflection and rotation to changes in the design parameters was derived for single and group piles. The distributed parameter sensitivity approach was used in the derivation with three different formulation techniques of the adjoint method. The design parameters considered were those defining the pile and the adjacent clay and sand. Five forms of sensitivity results were obtained. In the second part, various numerical sensitivity investigations were conducted including single piles and pile groups. Different pile lengths, pile head boundary conditions, and pile loadings were studied. In addition, the effect of pile spacing and pile location for a pile group, and the thickness of the overlying clay were investigated. More than 700 different cases for single and pile groups were studied using developed MATLAB programs, COM246P for single piles and FB-Pier for pile groups. The obtained results were verified by conducting an error analysis assessment. In the third part of this research, a user-friendly sensitivity program for laterally loaded piles was developed which allows the engineer to input his own data. The program is based on the theoretical formulation and is developed using MATLAB. It offers the numerical and graphical presentation of the five forms of sensitivity results. The results presented in this study enhance the understanding of the behavior of the laterally loaded pile-soil system. In addition, they allow the engineer to detect the critical locations of influence of each parameter along the pile length and quantitatively assess and compare that influence. Furthermore, an engineering tool for sensitivity is provided. Accordingly, the proposed research has considerable practical application in improving the design of the pile systems, solving infrastructure aging problems, monitoring processes, and helping in rehabilitation and renovation activities

Factors affecting the fire resistance properties of fly ash concrete

While a lot of research has been conducted under on sustainable building materials towards exploring the mechanical and physical properties of fly ash as a recycled material that replaces ordinary portland cement in concrete, little has been directed towards testing its fire resistance properties. Due to the growing need to use fly ash based concrete and the severity of fire, the third most reason for casualties in building inhabitants, this research is directed into exploring the fire resistance properties of fly ash based concrete. After conducting the literature review, the following hypothesis was formulated: not only does fly ash affect the behavior of the concrete, but also other test variables like the oven temperature, the curing period and several others. Therefore, an experimental program was formulated based on the literature findings in order to validate this hypothesis. Four hundred and eighty specimens were prepared to see whether the change in fly ash percentage, oven temperature, coarse aggregate size, curing time, curing method and steel reinforcement affects the fire resistance of concrete. Within the limitations of the experimental testing program, the following main findings can be stated; a) Concrete fire resistance property could be measured by a strength reduction index (Beta) that measures the decrease in compressive strength before and after being exposed to elevated temperatures, b) 30% FA samples has 20-25% higher Beta values than OPC Concrete in the early curing days (3 and 7), c) 30% FA samples has 10% higher Beta values on average in all tested oven temperatures, and d) concrete cured manually has higher Beta values than the ones in the curing room at 200 and 800 degrees

Pretensioning of single-crossarm stayed columns.

Dept. of Civil and Environmental Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1977 .H243. Source: Masters Abstracts International, Volume: 40-07, page: . Thesis (M.A.Sc.)--University of Windsor (Canada), 1977

SOIL-STEEL STRUCTURES UNDER SHALLOW COVER.

Soil-steel structures are flexible conduits made of corrugated metal sheets and buried in a well compacted granular media. Classical methods of design for conventional sized flexible buried conduits are simple and not suitable for long span structures, especially under relatively shallow cover. Herein, the live load effect cannot be considered secondary as in the case of conduits under deep cover. Also, field experience has shown that failure of the structure could be initiated by soil failure. The present codes avoid the problems associated with shallow cover by requiring a minimum depth of cover. This requirement is empirical and does not differentiate between the different shapes of conduits. A plane strain finite element analysis is developed and used to study long span soil-steel structures of different shapes under any depth of cover and loading condition with due consideration given to the soil state of stress. The structure wall is replaced by conventional beam elements. Soil is simulated by a combination of constant strain and linear strain compatible elements. Storage and time requirements for the numerical solution are kept to the lowest level without sacrificing the desired accuracy. Two-noded spring type interface elements are introduced between soil and culvert elements. Nonlinear stress-dependent hyperbolic relationships are used to model the soil and shear behaviour of interface elements. Construction procedure is simulated by automatically generating the finite element mesh layer by layer and by including the effect of compaction in the incremental analyses. Live load is applied concentrically or eccentrically, in increments. Initiation and propagation of soil failure are detected based on a curved Mohr envelope, and applying a stress transfer technique. A finite element program is developed on the basis of the foregoing analytical procedure to predict the state of stresses in the system due to dead and live loads, as well as the live load causing soil failure. The analytical results are compared with experimental results for live load tests conducted on existing long span soil-steel structures under shallow cover. The results of laboratory tests carried out until failure of soil are also compared with the analytically predicted values. Reasonable agreement is found in both cases. An analytical study establishes the parameters governing soil failure above the conduit. These parameters include the depth of cover, magnitude and position of loading, and the size and geometric shape of the conduit.Dept. of Civil and Environmental Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1982 .H244. Source: Dissertation Abstracts International, Volume: 43-03, Section: B, page: 0806. Thesis (Ph.D.)--University of Windsor (Canada), 1982

Developing ECO2: a performance based ecological and economic framework and tool for sustainability assessment of concrete

The use of concrete is associated with immense negative environmental impacts. More than 50 billion tonnes of aggregates are extracted annually for use in concrete, which presents high risks of depleting natural resources. Moreover, concrete has an embodied carbon footprint of 350 kg eq CO2/m3 on average of which 90% is attributable to the production of ordinary Portland cement (OPC). Although this is less than that of steel and most polymers per unit mass, the intensive use of concrete results in an alarming 7% share of the global carbon emissions. Therefore, increasing interest is being directed towards producing sustainable concrete. Conducting a Life cycle assessment (LCA) is a widely accepted tool to assess and compare the acclaimed environmental gains of these sustainable concrete types, while calculating the base line cost of each of these mixes could suffice for economic comparisons. However, sustainability is a multifaceted concept and in order to validate the sustainable of a concrete mix, multi criteria sustainability frameworks are needed. The critical examination of the only two frameworks found in the literature that fits this description, MARS-SC and CONCRETop, showed the need to develop a new one that covers their gaps, which inspired the main contribution in this PhD project. A novel ECOnomic and ECOlogical assessment framework for concrete (hence the name ECO2 which also refers to the symbolic carbon dioxide formula) was created with the following distinguishing features: 1. The scope specified for the LCA study is selected as Cradle-to-Grave in order to account for the whole life cycle of concrete. Therefore, the LCA inventory data, for which sitespecific primary data is prioritized, would include upstream data such as the impact allocation from previous processes from which the raw materials originated and downstream data such as the demolition and disposal impact of concrete. 2. The ECO2 framework considers the amount of carbon sequestration, which is the term used to describe how much carbon dioxide is absorbed by concrete from the environment. The accurate calculation of the carbon footprint of a concrete mix is vital for its absolute environmental impact assessment, but would soon in the near future also affect its economic impact when carbon taxation becomes a normal practice. Aside from filling the technical gaps of the sustainability assessment method, the main contribution the ECO2 framework brings is a shift in the philosophy related to the inclusion of the concrete performance in the process. In both reviewed frameworks (MARS-SC and CONCRETop), concrete performance is assessed as a separate pillar of sustainability perpetuating that the higher performance is rewarded with a higher sustainability index value. Instead, the ECO2 framework brings forward a two layered performance based methodology that promotes a value of resource efficiency. First, the user sets a minimum requirement for the workability and strength depending on the project specifications. The second layer is to correlate the expected service life of each qualifying concrete mix to the required service life of the concrete application within the project through a factor N. This factor, for which the minimum value is 1, is then multiplied by the functional unit used for the LCA to ensure that the economic and ecological assessment are not only accurate but also truly reflective of sustainability. An MS excel tool was also developed to self-validate the ECO2 framework in what could be labelled as a methodical contribution. Finally, three case studies were conducted using the newly developed ECO2 framework as follows: 1. The first case study was experimental using electric arc furnace slag as a precursor for alkali activated concrete and comparing its ECO2 sustainability index to a basic alkali activated concrete mix based on fly ash as a precursor. The case study showed that the deterioration in the mechanical properties of the novel alkali activated slag concrete largely overshadow the ecological and economic merits of recycling it. 2. The second case study was analytical using a database of more than 2500 data points to predict and hence optimize the functional, environmental and economic performance of blended cement concrete using the ECO2 framework. The mixes included varying combinations of five different types of SCMs based on plain and reinforced concrete scenarios of different strength and service life requirements. 3. The final case study was prepared to investigate an issue facing the UK Green concrete market which is the need to shut down all coal operated electrical power plants by 2022 and the subsequent absence of fly ash. The case study used the ECO2 framework to compare between importing fly ash from China, Germany and recycling locally existing stockpiled fly ash in the UK. The vital parameter in the comparison was the environmental and economic impact resulting from the transportation of fly ash from its source to the location of the concrete batch plant in the UK

A Systematic Review of the Discrepancies in Life Cycle Assessments of Green Concrete

It is challenging to measure the environmental impact of concrete with the absence of a consensus on a standardized methodology for life cycle assessment (LCA). Consequently, the values communicated in the literature for “green” concrete alternatives vary widely between 84 and 612 kg eq CO2/m3. This does not provide enough evidence regarding the acclaimed environmental benefits compared to ordinary Portland cement concrete knowing that the average for the latter was concluded in this study to be around 370 kg eq CO2/m3. Thus, the purpose of this study was to survey the literature on concrete LCAs in an attempt to identify the potential sources of discrepancies and propose a potential solution. This was done through examining 146 papers systematically and attributing the sources of error to the four stages of an LCA: scope definition, inventory data, impact assessment and results interpretations. The main findings showed that there are 13 main sources of discrepancies in a concrete LCA that contribute to the incompatibility between the results. These sources varied between (i) user-based choices such as depending on a cradle-to-gate scope, selecting a basic volume-based functional unit and ignoring the impact allocation and (ii) intrinsic uncertainty in some of the elements, such as the means of transportation, the expected service life and fluctuations in market prices. The former affects the reliability of a study, and hence, a concrete LCA methodology should not allow for any of the uncertainties. On the other hand, the latter affects the degree of uncertainty of the final outcome, and hence, we recommended conducting scenario analyses and communicating the aggregated uncertainty through the selected indicators

Identifying the risk factors affecting the overall cost risk in residential projects at the early stage

Many previous studies have developed models for estimating the total cost, whether in the planning stage or the early stage of the project. However, models for estimating the overall risk were proposed in the planning stage only. This paper identifies the factors affecting the overall risk in residential projects at the early stage. The 43 risk factors at the planning stage were identified using a Delphi technique. Experts summarize the 43 risk factors into four factors that can be used to predict the overall risk in the early stage of the project. A multilayer perceptron model with one hidden layer was proposed. The mean absolute error rate for the proposed model was 10%. Risk factors can be used to develop a model to predict the impact of overall risk on project cost at the early stage. The developed model helps stakeholders decide whether the project should continue or be terminated

Lean partially premixed turbulent flame equivalence ratio measurements using laser-induced breakdown spectroscopy

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.The creation of a more stable flame along with the extension of flammability limits under lean mixture combustion was the main motivation to develop a new burner design, which has been investigated in this research. The current burner configuration was utilized to create a wide range of higher turbulent intensities and to produce different degrees of mixture inhomogeneity, which acted to promote minimum pollution, highest performance and higher flame stability. The burner stability assessment was investigated using two types of fuel: natural gas (NG) and liquefied petroleum gas (LPG). They were tested under different degrees of partial premixing, and two turbulence generator disks for lean mixture at an equivalence ratio of φ = 0.8 were used. Following this, the Laser Induced Breakdown Spectroscopy (LIBS) technique was utilized to characterize and quantify the impact of changing the disk slit diameter on the distributions profiles of equivalence ratio or mixture fraction for a NG/air partially premixed flame. A series of homogeneous NG/air mixtures with different equivalence ratios were used to obtain the correlations between the measured emission lines of LIBS spectra and the global flame equivalence ratio. Consequently, the emission spectral lines ratios of H/N, H/O and C/N + O were utilized to predict the equivalence ratio distributions. The results demonstrated that for all of the mixing lengths, NG/air mixture with larger disk generator diameter yielded the maximum burner stability, whilst the LPG/air mixture with a larger disk generator diameter resulted in the minimum burner stability. Furthermore, the flame associated with the larger disk slit diameter had a uniform local equivalence ratio distribution and lower RMS fluctuation profiles of equivalence ratio in comparison to the lower disk slit diameter

Data-driven optimization tool for the functional, economic, and environmental properties of blended cement concrete using supplementary cementitious materials

The need to produce more sustainable concrete is proving imminent given the rising environmental concerns facing the industry. Blended cement concrete, based on any of the prominent supplementary cementitious materials (SCMs) such as fly ash, ground granulated blast-furnace slag, silica fume, calcined clay and limestone powder, have proven to be the best candidates for sustainable concrete mixes. However, a reliable sustainability measure includes not only the environmental impact, but also the economic and functional ones. Within these five SCMs, their environmental, economic and functional properties are found to be conflicting at times, making a clear judgement on what would be the optimum mix not a straightforward path. A recent framework and tool for concrete sustainability assessment ECO2, sets a reliable methodology for including the functional performance of a concrete mix depending on project-based specifications. Therefore, in this study, a recently published regression model, Pre-bcc was used to predict the functional properties of a wide grid search of potentially suitable blended cement concrete mixes. Hence, an open access novel genetic algorithm tool “Opt-bcc” was developed and used to optimize the sustainability score of these mixes based on a set selection of user-defined project-specific functional criteria. The optimized mixes using the Opt-bcc model for each strength class were compared against the mix design proposed by other optimization models from the literature and were found to be at least 70% cheaper and of 30% less environmental impact.Peer ReviewedPostprint (published version