The ETD presented is but a simplistic representation of the time spent pursuing a proposition: what is the architecture of concrete? The timeline began in the Fall Semester of 2012 in Alexandria Virginia and ended as a formal built presentation on site to the committee in June of 2016. In its incipient form the thesis began with traditional and instructive methods involving ideas and theory. The ideas were refined by demonstration of the repertoire of tools available to an architect: hand drawings, physical models of different scales using a variety of media implicating concrete, and modern digital models transcending scale. Architecture requires that the tools, drawings, and models used in architecture respond to the site. To understand the site, I analyzed the site via various metrics, senses, and sensibilities. Upon further discussion, investigation, and opportunity, the committee allowed my proposition to transform itself into the architecture of concrete via the process of the art of building. The process lasted over two and a half years upon which I lived on site until the thesis was complete. / Master of Architecture

The need for a space for the community to gather and the underutilization of the waterfront led to the design of a public space for Alexandria. A school of culinary design was chosen to elevate the current situation of the site by supporting the open space and giving back to the community. The culinary school served as a vessel to explore the truthfulness of materials and structure, and the aesthetics of the unfinished. The design of the culinary school conveys the story of its making by revealing the structural elements and not covering them with unnecessary finishes. The materials used in the design are true to their nature. The project serves as a place to create culinary art and to express the spirit of the architecture. / Master of Architecture

This paper presents the behaviour and design of axially loaded elliptical steel hollow sections filled with normal and high strength concrete. The experimental investigation was conducted with three nominal wall thickness (4mm, 5mm and 6.3mm) and different infill concrete cube strengths varied from 30 to 100 MPa. The effect of steel tube thickness, concrete strength, and confinement were discussed together with column strengths and load-axial shortening curves were evaluated. The study is limited to cross-section capacity and has not been validated at member level. Comparisons of the tests results together with other available results from the literature have been made with current design method used for the design of composite circular steel sections in Eurocode 4 and AISC codes. It was found that existing design guidance for concrete filled circular hollow sections may generally be safely applied to concrete filled elliptical steel tubes.

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Pavement concrete joints are the weakest locations in concrete pavement systems. They are man-made cracks to accommodate concrete slab expansion and contraction due to temperature fluctuations. Sealant is usually used in pavement joints to prevent roadway debris, deicing chemicals, and moisture from entering the joint. When sealant fails, the pavement deteriorates rapidly; and when joint sealant performs adequately, the pavement preserves its intended performance. In the field, joint sealant undergoes two types of mechanical loading simultaneously. The sealant is experiencing tension or compression as slabs contract (low temperature) or expand (high temperature), respectively. Sealants also experience shear as heavy trucks travel over the joint and deflect the ends of the pavement slabs. In addition, sealants may also be exposed to a variety of environmental conditions, such as moisture, ultraviolet light, and jet fuel, which in some cases could be detrimental to their performance. In this study, the effects of vehicular and environmental loading on joint sealant performance were evaluated. To simulate the sealed joint performance, specimens were constructed by sandwiching a sealant between two 50.8 mm Portland cement concrete (PCC) cubes. Prior to mechanical loading, specimens were subjected to partial immersion in distilled water, partial immersion in jet fuel, and/or exposure to UV-A light. The specimens were then subjected to static horizontal tension, simulating slab contraction, and cyclic deflection-controlled shear, simulating heavy trucks travelling over the joint. The cycle consists of one 0.2 second period of sinusoidal loading (total 6.4 mm deflection) followed by a 0.4 second relaxation. The mechanical loading was applied using a special fixture developed at Virginia Tech, which is connected to a closed-loop servo-hydraulic loading machine. Two types of sealants (preformed neoprene and field-molded silicone with a primer) were tested using PCC mixes with two different aggregate types. In, addition, two different joint widths were evaluated for each sealant type. From the results of the cyclic testing and environmental conditioning, it was shown that the use of a primer greatly enhances the performance of the silicone sealant used with concrete containing limestone aggregate. In addition, severe swelling occurs when silicone sealant is exposed to jet fuel, and the failure of the field-molded silicone initiated at the bottom of the sealant and propagated upward. The preformed neoprene sealants proved very durable despite any combination of environmental conditioning, provided that the sealant remained in compression. / Master of Science

concrete has a memory. It stores the construction sequences. It shows what it is made of and how it is made. The texture of the formwork, the color difference of the pours, and the shadows of the metal ties combine to layer the beauty of concrete. The aim of this study is to explore the instruments of a concrete surface in order to enhance this multi-sensory experience. This study began with the design of a concrete wall and evolved into the design of a single-family home. / Master of Architecture

Building for concrete is temporary. The building of wood and steel stands against the concrete to give form and then gives way, leaving a trace of its existence behind. Concrete is not a building material. One does not build with concrete. One builds for concrete. / Master of Architecture

The thesis started from the nostalgia for the historic district and the life within it. I don't agree with the radical method of reforming the historic district at the moment, which is rebuilding the whole district or demolishing it. I tried to find a new way to reform the historic district, so that the new project can blend into the habitats' lifestyle, in which way people can reconnect to their home land. During the design process, there is movie scenes, kungfu novels, and the living moment from my childhood came to my mind. And I translate those scenes into the spaces in the project through an architectural language. / Master of Architecture / I tried to find a new way to reform the historic district, so that the new project can blend into the habitats' lifestyle, in which way people can reconnect to their home land. During the design process, there is movie scenes, kungfu novels, and the living moment from my childhood came to my mind. And I translate those scenes into the spaces in the project through an architectural language.

This thesis explores the variety of spatial conditions that can be created with simple planar elements by modulating light. The result is an architectural space in which children better comprehend natural phenomena through the constellation of architectural elements. / Master of Architecture

It is quite well known that fracture behavior of concrete is complex and is influenced by several factors. Apart from material properties, geometric parameters influence fracture behavior and one notable phenomenon is size effect. The existence of the size effect in concrete is well known and various attempts to model the behavior is well documented in literature. However the approach by Bazant to describe the size effect behavior in concrete has received considerable attention. The major advantage of developing the size effect law for concrete is the ability to describe the fracture behavior (namely failure strength) of large size structures inaccessible to laboratory testing. The prediction of size effect is done on the basis of laboratory testing of small size geometrically similar structures. In all the models developed earlier heterogeneity of concrete has not been quantitatively simulated. Hence, the complete description considering heterogeneity in concrete is attempted using the lattice model to understand size effect behavior in concrete. In the present study, a detailed description of the heterogeneity in concrete is at- tempted by 3D lattice structure. Analytical treatment to gain insights to fracture behavior is difficult and hence a numerical approach capable of handling the het- erogeneous nature of the material is adopted. A parametric study is performed to understand the influence of various model parameters like mesh size, failure criterion, softening model. The conventional size effect studies for 2D geometrically similar structures are performed and a comparison is done with experimentally observed behavior. The variation of fracture process zone with respect to structure size is observed as the reason for size effect. The influence of variation in properties of ag- gregate, matrix and interface are studied to explain the deviation in pre-peak and post-peak response. A statistical study is performed to establish the size dependence of linear regression parameters (Bf ‘t and D0) which are used in Bazant size effect law. An analytical framework is also proposed to substantiate the above results. Size effect in concrete is generally attributed to the effect of depth viz. the dimension in the plane of loads. However although the effect of thickness viz. a dimension in a plane perpendicular to that of the loads is not considered in concrete. The same is quite well known in fracture of metals. Therefore the variation in grading of aggregates along with the influence of thickness on fracture behavior is analysed. To understand the thickness effect a comparison of 2D and 3D geometrically similar structures is performed to understand the effect of thickness on fracture parameters. Heterogeneity is a matter of scale. A material may be homogeneous at a coarser scale while at a finer scale it is heterogeneous. Hence only way to capture the effect of the behavior at micro level on the behavior at meso level particularly in a heterogeneous material like concrete is by a multi-scale modelling. The best numerical tool for multiscale model of a heterogeneous material is lattice model. The heterogeneous nature of concrete is not just due to the presence of aggregates but is evident right from the granular characteristics of cement. The hydration of cement grain leads to the development of products with varying mechanical and chemical properties. As the micro-crack initiation and development of thermal cracking is observed at the micron level, understanding of hydration behavior in concrete can be thought of as a pre-requisite for complete understanding of fracture behavior. The properties of matrix and interface observed during hydration modelling can also be used as an input for fracture predictions at upper scale models (eg. mesoscale). This can also be used to study the coupling of scales to understand the multi-scale fracture behavior in concrete. A numerical model is hence developed to study the hydration of concrete. Due to the existence of complex mechanisms governing the hydration behavior in con- crete and the large number of parameters affecting its rate, the hydration of a grain is assumed to proceed in isolation. A single particle hydration model is developed to study the hydration of isolated grain. A shrinking core model usually used to describe the burning of coal is adopted as a base model for analytically describing the hydra- tion behavior. The shrinkage core model in literature is modified to be applicable to hydration of cement matrix. The effect of particle diameter as well as changing water concentration is incorporated into the model whereas the influence of reduction in pore sizes as well as the effect due to embedding of particles and the constraint due to hydration of neighbouring particles is accounted using correction factor. The effect of temperature on rate of hydration is considered to be independent of the physical and chemical aspects of grain. Hence a temperature function developed using Arrhe- nius equation and activation energy is incorporated separately. The porous nature of reaction products affects the diffusivity leading to the development of tortuous path for flow of water through the hydrated portion. Knowing the tortuosity it is possible to obtain the diffusivity which in turn can be used as an input to the lattice model. An algorithm is developed to determine the tortuosity in diffusion of water through the reaction products. The tortuosity depends on the distribution of pores in the hydrated system. This requires the use of simulation technique to generate the initial position of voids. A simulation technique is also required to generate the initial con- figuration of hydrating cement system. In order to generate the initial configurations of such systems a numerical technique to generate a large scale assembly of particles is proposed. In the present work, parameters of Bazant's size effect law Bf’t and D0 are shown to depend on structure size and heterogeneity. The span to thickness ratio of the structure increases fracture energy and also substantially influences the response of structure. The variation in failure load occurring due to the heterogeneous nature of the material is shown to follow a normal distribution. The fracture behavior of a material is seen to be influenced strongly by the variation in the strength of matrix and interface. The model proposed to describe the hydration process of cement can be used to determine the properties of matrix and interface. The degree of hydration as well as the embedded centre plane area can be adopted as a measure of strength of matrix and interface. The understanding of the hydration process and the wall effect around the aggregate surface can possibly improve our ability to predict the strength of interface. The material strength of the interface is certainly a necessary input to the lattice model. Infact experimental determination of interface strength is a lot more complicated than the present numerical approach. The only weakness of the present numerical approach is the assumption regarding certain empirical constants which of course may be improved further. Understanding of material behavior can be further improved if a molecular dynamics approach is adopted to describe the hydration behavior of cement. The approach via molecular dynamics is suggested as a problem for future research.