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Incombustibility is one important advantage of the sheet steel sheathed shear wall over wood panel sheathed shear wall. Compared to shear wall sheathed with plywood and OSB panel, shear wall sheathed with flat sheet steel behaved lower shear strength. Although shear wall sheathed with corrugated sheet steel exhibited high nominal strength and high stiffness, the shear wall usually behaved lower ductility resulting from brittle failure at the connection between the sheathing to frames. This research is aimed at developing modifications on the corrugated sheathing to improve the ductility of the shear wall as well as derive practical response modification factor by establishing correct relationship between ductility factor ? and response modification factor R. Totally 21 monotonic and cyclic full-scale shear wall tests were conducted during the winter break in 2012 by the author in NUCONSTEEL Materials Testing Laboratory in the University of North Texas. The research investigated nineteen 8 ft. × 4 ft. shear walls with 68 mil frames and 27 mil corrugation sheet steel in 11 configurations and two more shear walls sheathed with 6/17-in.OSB and 15/32-in. plywood respectively for comparison. The shear walls, which were in some special cutting arrangement patterns, performed better under lateral load conditions according to the behavior of ductility and shear strength and could be used as lateral system in construction.

Thesis advisor: Seth C. Kruckenberg / The Burlington Mylonite Zone (BMZ) is a northeast-trending, greenschist- to amphibolite-facies shear zone located entirely within the Boston Avalon terrane in Eastern Massachusetts along the tectonic boundary with the Nashoba terrane (the trailing marginal terrane of Ganderia). The juxtaposition of these terranes, and the development of the BMZ, is hypothesized to represent the amalgamation of Avalon and Laurentia during the late Silurian-early Devonian Acadian orogeny, but the timing of its formation and its structural evolution remain largely unconstrained. Field observations and microstructural analysis using electron backscatter diffraction (EBSD) of 24 samples from 16 field sites throughout the BMZ provide new constraints on the kinematics and conditions of deformation that facilitated the development of this large-scale crustal shear zone. The BMZ samples comprise a heterogeneous mix of quartzofeldspathic +/- hornblende-bearing gneisses and quartzites with varying microstructures. Nearly all samples contain abundant mixed, but predominantly sinistral, kinematic indicators (e.g., asymmetric porphyroclasts, tiled feldspars) and a strong crystallographic preferred orientation (CPO). Quartz – the dominant mineral by mode in all of the samples analyzed – is known from experimental deformation studies to develop distinct patterns of CPO which vary as a function of deformation kinematics, temperature, and strain geometry. Patterns of CPO in quartz are used to determine the dominant intracrystalline deformation mechanisms that accommodated the formation of the BMZ. Quartz CPO patterns in the BMZ samples are characterized by variably developed c- and a-axis distributions, broadly consistent with patterns expected for mixed<a> to prism<a> slip at intermediate temperatures of deformation. Corresponding intragranular misorientation axis plots are more diagnostic and indicate dominant prism<a> slip in all of the shear zone samples analyzed, consistent with microstructures observed in thin section (e.g., undulose extinction, subgrain development, grain boundary migration, dynamic recrystallization) and metamorphic conditions inferred from shear zone mineral parageneses. Application of the quartz recrystallized grain size piezometer places additional constraints on deformation conditions, indicating that the BMZ rocks record differential stresses ranging from ~44 to 92 MPa. Field and microstructural observations of shear sense indicators are combined with two analytical methods for determining aspects of kinematic vorticity and deformation geometry in the BMZ. This study applies a new analytical method - crystallographic vorticity axis (CVA) analysis - that leverages rotational statistics on crystallographic orientations within the interiors of grains to constrain the dominant axis of material rotation in deformed samples. This dominant axis provides a uniquely objective proxy for the vorticity normal reference frame required for further quantitative kinematic vorticity analyses. The rotational axis of kinematic vorticity, and its relationship to structural fabrics (i.e. foliation and lineation), provides an important constraint on the geometry of the deforming zone (e.g., monoclinic versus triclinic shear zones). The results of the CVA analysis are invariable across the entire length of the BMZ; the kinematic vorticity axis lies within the plane of mylonitic foliation perpendicular to lineation – the pattern expected for monoclinic deformation geometries. The mean kinematic vorticity number (Wm: a measure of the relative contribution of pure and simple shear) is calculated using Rigid Grain Net (RGN) analysis for the BMZ mylonites and ranges from 0.4-0.5, indicating general shear. Combined field, microstructural, and vorticity analyses are interpreted to suggest that crustal strain localization along the Avalon-Nashoba boundary, as recorded in the BMZ mylonites, involved the combined effects of pure and simple shear in a predominantly sinistral, monoclinic transpressional shear zone. Rock microstructures, patterns of crystallographic preferred orientation, and paleostress estimates suggest that mylonitization occurred at or near the brittle-ductile transition under relatively high stress conditions. This study demonstrates the power of new microstructural methods, such as CVA analysis of electron backscatter diffraction data, to augment traditional field-based methods of kinematics and deformation analysis in enigmatic, large-scale crustal shear zones.

The mixing of powders and liquids is a process ubiquitous to many industrial, research and household applications, from the production of foodstuffs, pharmaceutical and cosmetic products to the preparation of hot drinks or cement. The final mixed state of powders and liquids can be broadly split into two distinct regimes identified respectively as having low- and high volume fraction, ∅. Low-∅ systems are typified by flowing suspensions whereas samples prepared with high-∅, beyond some threshold value, produce solid agglomerates which are unable to flow. These two regimes are the focus of two separate scientific disciplines; suspension rheology and granulation. Within the field of suspension rheology there has been recent advances in the understanding of a phenomena known as shear thickening, which describes the increase in a suspension's viscosity with increasing applied stress. In this thesis we aim to unify the phenomena of shear thickening and granulation within this new theoretical framework. We study shear thickening and granulation using a well characterised model system developed for this purpose, comprising polydisperse glass particles with a mean diameter of ≃ 7 μm and a glycerol-water mixture (90:10 %vol). We measured the rheological behaviour as a function of applied stress, σ, of suspensions at various volume fractions. We observed shear thickening behaviour, with divergences in the low-stress viscosity, η1(∅), and the high-stress viscosity, η2(∅), at ∅RCP = 0:662 and ∅m = 0:572 respectively. These divergences mark the transition between continuous shear thickening, discontinuous shear thickening and a state in which flow is not possible, with increasing volume fraction. Using a recently developed theory of shear thickening (Wyart and Cates, 2014), we were able to fit our rheological data quantitatively. The WC theory predicts a stress-dependent crossover in the fraction of contacts which are frictional in nature, following a stretched exponential function. In order to improve numerical agreement between our data and the model, we developed a method taking into account the volume-weighted contribution of particle sizes in our polydisperse system. Bulk mixing of the same model system in a custom-built high-shear mixer also exhibited three different mixing regimes with the change in behaviour coinciding with the location of the viscosity divergences, ∅m and ∅RCP, measured in the rheology experiments. For ∅ < ∅m suspensions are formed at both high and low stress; for ∅ ≥ ∅RCP granules are formed at all stresses; for ∅m ≤ ∅ < ∅RCP transient granules are formed, which are solid at high stresses, but can relax to a flowing suspension state at low stress. This transient behaviour is reversible with the application of high stress. This coincidence of viscosity divergence in the rheology measurements and mixing behaviour change in the high-shear mixing strongly suggests that the two phenomena are related. Thus we used the stress-dependent jamming volume fraction, ∅J(σ), predicted by the WC theory, to define the transition between the formation of suspensions and granules. We were able to calculate a quantitative phase diagram, with which the regions of the ∅-σ phase space in which granules or suspensions are formed can be easily identified, in agreement with our high-shear mixer data. Thus, using small-scale rheological measurements, requiring relatively small volumes of sample, we are able to define the parameter space in which granules can be prepared, thus eliminating the need for trial and error granulation experiments in order to define this space. We measured the volume-weighted mean granule size as a function of ∅ in the range ∅m → ∅ ≃ 0:85. Based on our observations of granule structure and measurements of granule size distributions, we modelled the granules as an ensemble of core-shell agglomerates with a log-normal size distribution. The packing in the granule cores was assumed to be ∅J(σ ), i.e. ∅m at high stress and ∅RCP at low stress. Appealing to conservation of mass arguments, our model predicts that the mean granule size decreases with increasing volume fraction and stress, in quantitative agreement with experimental data.

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This study concerns the strength and behaviour of low-rise shear walls made from high-strength concrete under reversed cyclic loading. The response of such walls is often strongly governed by the shear effects leading to the shear induced or brittle failure. The brittle nature of high-strength concrete poses further difficulties in obtaining ductile response from shear walls. An experimental program consisting of six high-strength concrete shear walls was carried out. Specimens were tested under inplane axial load and reversed cyclic displacements with the test parameters investigated being longitudinal reinforcement ratio, transverse reinforcement ratio and axial load. Lateral loads, lateral displacements and the strains of reinforcement in edge elements and web wall were measured. The test results showed the presence of axial load has a significant effect on the strength and ductility of the shear walls. The axially loaded wall specimens exhibited a brittle behaviour regardless of reinforcement ratio whereas the specimen with no axial load had a lower strength but higher ductility. It was also found that an increase in the longitudinal reinforcement ratio gave an increase in the failure load while an increase in the transverse reinforcement ratio had no significant effect on the strength but influenced the failure mode. A non-linear finite element program based on the crack membrane model and using smeared-fixed crack approach was developed with a new aggregate interlock model incorporated into the finite element procedure. The finite element model was corroborated by experimental results of shear panels and walls. The finite element analysis of shear wall specimens indicated that while strengths can be predicted reasonably, the stiffness of edge elements has a significant effect on the deformational results for two-dimensional analyses. Therefore, to capture the deformation of walls accurately, three-dimensional finite element analyses are required. The shear wall design provisions given in the current Australian Standard and the Building Code of American Concrete Institute were compared with the experimental results. The comparison showed that the calculated strengths based on the codes are considerably conservative, specially when there exists the axial load.

The aim of this work was to use simulation as a tool to better understand areas of orthokinetic (shear-induced) aggregation which are still not well understood. These areas include aggregate structure, aggregate strength, breakup and restructuring and combined perikinetic/orthokinetic aggregation. Previous simulation studies were reviewed and it was concluded that the methodology of Chen and Doi (1989) was an appropriate starting point for this study. The modified simulation was validated by comparison with theoretical and experimental results. Orthokinetic aggregates were found to have a fractal structure with an estimated value of 1.65. Scaling exponents, which were shown to be indicative of fractal dimension, of 2.1-2.7 were also obtained. Flexible bonds allowed restructuring to occur which led to an increase in the co-ordination number, scaling exponent, aggregate strength and a reduction in aggregate size. Thus aggregate strength increases with fractal dimension. It was confirmed that both restructuring and breakup/reformation could lead to the formation of small, compact aggregates. The high shear conditions simulated favoured breakup/reformation, while restructuring was expected to dominate with more flexible bonds, possibly at lower shear rates. Taking some account of hydrodynamic interactions by the inclusion of Kirkwood-Riseman theory led to an increase in the compactness of the aggregates and the co-ordination numbers, as well as a decrease in size of the aggregates. The results showed that hydrodynamic interactions can not be ignored. The explanation for the dramatic effects was that particles/microflocs on the outer edges of the aggregates broke off and reformed in a more compact way. Erosion was found to dominate in all cases, thus supporting the theory that erosion dominates at higher fractal dimensions. The shearing range simulated was found to be relatively high (equivalent to &lt200s-1 for particles of 2-5??m), producing relatively small aggregates. Hence it is proposed that under high shear conditions, erosion dominates. It was shown by extension of the DLCA algorithmic restructuring work of Meakin and Jullien (1988, 1989) that the scattering patterns observed in gently sheared aggregating systems are consistent with the interpretation that the shearing causes partial restructuring at large length scales.