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Item Effect of spatial variability of soil and soil-cement ground reinforcement on behavior of soil and overlying structures under static and dynamic loadings(Montana State University - Bozeman, College of Engineering, 2022) Zaregarizi, Shahabeddin; Chairperson, Graduate Committee: Mohammad Khosravi; This is a manuscript style paper that includes co-authored chapters.This study presents the results of spatial variability effect of soil and soil-cement (SC) ground reinforcement on behavior of soil and overlying structures under static and dynamic loadings. The objective is to evaluate the improvement/merit of employing stochastic modeling approaches, such as spatially correlated random fields, relative to deterministic analysis with uniform properties for the soil and SC walls. The results of studies are used to provide a representative SC shear strength for use in practical applications to account for spatial variability in soil-cement strength properties.Item Aggregate piers: stress transfer mechanism and construction effect(Montana State University - Bozeman, College of Engineering, 2022) Gamboa, William; Chairperson, Graduate Committee: Mohammad KhosraviThis thesis is a compilation of two different papers based on the behavior of aggregate piers which is a soil improvement method used to increase the bearing capacity and reduce the expected settlements of soils in which different types of structures are supported. The first paper describes the results of two modulus load tests and a dimensional finite difference analysis (FDA) conducted to evaluate the load-displacement response of isolated aggregate piers. Load test aggregate piers were constructed with two different materials: the first one with 38 mm base coarse and the second one with 75 mm subbase coarse materials. The numerical analyses provided reasonable predictions of the load-displacement response of the isolated aggregate piers. Parametric analyses using the validated numerical model illustrate that the lateral stress increment on the soil around the pier during the installation process of the pier should be considered in the numerical analysis, otherwise the settlement can be overestimated. The second paper is based on two full-scale load tests that were conducted to examine the load transfer mechanisms of end-bearing single and group aggregate piers. The first included a load test on a 0.76 m diameter isolated aggregate pier. The length of the aggregate pier was 4.3 m. The second test included a 2.1 m square reinforced concrete footing supported by four 0.76 m diameter aggregate piers of 4.3 m long. The soil consists of soft to medium stiff layers of sandy and clayey silt overlain by a 2-m-thick, softer silty clay layer. At the bottom, weathered rock was found. The load transfer mechanism within the length of the piers was examined using a series of load cells and tell-tale reference plates installed at different depths of the aggregate piers. Additionally, the installation effect was investigated using Cone Penetration Tests (CPT) conducted prior and after construction of the aggregate piers and inclinometers installed at multiple locations around the aggregate piers. The results of the experiments were compared with those in the literature to provide insights on the performance of aggregate piers with different configurations (single vs. group) and depths (floating vs end-bearing) in different soil profiles.Item The influence of external load during hiking on markers of joint stress and movement efficacy(Montana State University - Bozeman, College of Education, Health & Human Development, 2022) Rowland, Isaac Franco; Chairperson, Graduate Committee: Mary P. Miles; Mary Miles, David Graham, Ron June, Brian Bothner and Hunter Fausset were co-authors of the article, 'The influence of external load during hiking on markers of joint stress and movement efficacy' which is contained within this thesis.PURPOSE: Complications to lower extremity joints, including injury and inflammation, are prevalent issues that arise during prolonged external load-bearing exercise. Metabolomic blood analysis can provide insight into the metabolic processes that occurs during this type of exercise. METHODS: Eight healthy, active men and women participated in a series of blood sample collections and motion capture recording before and after completing a 7.2-mile hiking protocol under two separate conditions. Blood was collected prior to hiking, 15-20 minutes after hiking, 8-hours after, 24-hours after, and 48 hours after. Movement coordination and efficacy was measured with a motion capture system while performing the y-balance test and an obstacle clearance task. Hiking conditions were randomized as backpacking with 20% of body mass external load or daypacking with minimal external load for each participant and separated by two weeks. Serum was analyzed to detect differences in metabolite upregulation between conditions. Biomechanical data were analyzed for inter- and intra-differential values relevant to fatigue between conditions. RESULTS: Analysis found clear differences between conditional metabolite upregulation at all post-hike timepoints. The upregulation of cortisol was significant in backpacking conditions at the post-hike timepoint. Glycerophospholipids were significantly upregulated in backpacking at 8-hours post-hike All significant metabolite upregulation switched to daypacking conditions at 24-hours post-hike. Significant metabolite upregulation varied between conditions at 48-hours post-hike. The only findings of significance in movement coordination and efficacy were between the y-balance lateral leg movement. CONCLUSIONS: The presence of cortisol is consistent with the physiological and mental stress of external loadcarriage and alludes to exposure that can lead to decreased bone mineral content. Glycerophospholipid metabolism pathways play an important role in joint degradation, which could explain their upregulation in backpacking conditions. Ceramide, omega-3s, and fatty acid/triglyceride cycling are functions of cell proliferation and turnover which may be upregulated with more efficiency in daypacking conditions. Upregulation of anserine at 48-hours post-hike in daypacking supports the idea of more efficient exercise recovery occurring in this condition. While significant differences were not clear in motor control measures, the findings show potential reliability for future study designs.Item Coordination and coordination variability during running with respect to internal loading and age(Montana State University - Bozeman, College of Education, Health & Human Development, 2021) Hoffee, Allison Jane; Chairperson, Graduate Committee: James P. Becker; David Graham, Scott Monfort and James Becker were co-authors of the article, 'Coordination variability predicts achilles tendon and peak patellofemoral loading in healthy runners' submitted to the journal 'Clinical biomechanics' which is contained within this thesis.; Scott Monfort, David Graham and James Becker were co-authors of the article, 'Comparison of coordination and coordination variability between adolescent and adult runners' submitted to the journal 'Journal of sports sciences' which is contained within this thesis.Running is a largely popular and widely accessible form of exercise. However, running may pose risks to individuals due to its associations with high rates of injuries. Coordination between lower extremity joints and segments as well as coordination variability have linked to these running injuries. While mechanisms of injury are multifactorial, one theory suggests that reduced coordination variability may cause injury by increasing cumulative loading of soft tissue structures. This relationship may be important when assessing age, as prevalence of injuries differ between adolescents and adults. Therefore, this thesis aimed to 1) assess the relationship between coordination variability and loads in the Achilles tendon and patellofemoral joint during running 2) and evaluate differences in segmental coordination and variability between adolescent and collegiate runners. In Study 1, 64 healthy, adult runners ran on an instrumented treadmill while kinematics and kinetics were recorded. Coordination variability for knee-shank, knee-rearfoot, and shank-rearfoot couplings were calculated using vector coding. Achilles tendon and patellofemoral kinetics were calculated with musculoskeletal models. Surrogate variables were created for Achilles tendon and patellofemoral metrics using principal component analyses, and regressions were used to determine whether variability metrics predicted loading surrogates. One surrogate variable was created for Achilles loading, and lower knee-rearfoot variability predicted greater Achilles loading. Two surrogate variables were created for patellofemoral loading. Lower knee-rearfoot and knee-shank variability predicted greater peak patellofemoral loading, but no variability predicted cumulative patellofemoral loading. This suggests that a combination of low variability and large loads may be important for injury risk rather than cumulative loading. Study 2 assessed 21 competitive adolescent and 21 collegiate runners. Coordination variability was calculated using vector coding for various thigh, shank, and rearfoot couplings. Coordination patterns were analyzed using a binning frequency analysis. Adolescent and collegiate runners displayed different coordination patterns while running that primarily emerged from the transverse plane. Adolescent runners displayed greater coordination variability on average than collegiate runners. Combined with previous literature, this suggests a downward trend in coordination variability starting in adolescence and continuing through adulthood. In conclusion, coordination and its variability may be consequential in terms of injury mechanisms and different age populations.Item Patellofemoral joint loading in females during back squats of varying depth, weight load, and stance width(Montana State University - Bozeman, College of Education, Health & Human Development, 2019) Zavala, Linnea Joy; Chairperson, Graduate Committee: James P. Becker; Victoria Flores, Joshua Cotter and James Becker were co-authors of the article, 'Patellofemoral joint loading in females when using different depths and loads in the back squat' submitted to the journal 'Journal of applied biomechanics' which is contained within this thesis.; James Becker was a co-author of the article, 'Patellofemoral joint loading in females during back squats with varying stance widths' submitted to the journal 'Journal of orthopedic sports physical therapy' which is contained within this thesis.As a repetitive and loaded exercise, the back squat can lead to tissue injury. One concern is patellofemoral pain syndrome, a common knee diagnoses over twice as prevalent in females as in males. Patellofemoral joint stress is cited as a cause of the syndrome. To manage the syndrome, quadriceps strength is important. Although the back squat is a good exercise for quadricep strength, modifications to squat technique may be necessary to decrease patellofemoral joint stress. Two studies on female recreational athletes are addressed here: 1) how patellofemoral joint loading changes with squat depth and load and 2) how it changes with squat load and stance width. Depth-specific 1-repetition maximums were measured, and weight loads were based on percentages of the maximum. Peak knee extensor moments, patellofemoral joint reaction forces, and patellofemoral joint stresses were calculated using inverse dynamics and previously reported equations. First, participants squatted to 90°, ~°110, and ~135° of knee flexion with loads of 0%, 50%, and 85% of 1RM. A depth-by-load interaction was found such that within each depth, moments increased as load increased, while decreasing with increased depth. Patellofemoral joint reaction force had main effects of load and depth such that as load increased or depth decreased, reaction force increased. Another depth-by-load interaction was found such that within each depth, as load increased the stress increased, while increasing with increased depth. From these results, squats to full depth or loaded squats to less than 90° of knee flexion are recommended to minimize patellofemoral joint stress. Second, when squatting to ~110° with loads of 35% and 85% and stance widths of 90%, 100%, 110%, and 120% of natural stance, there was a main effect of load for knee extensor moment, patellofemoral joint reaction force, and patellofemoral joint stress. Although altering stance width does not appear to change joint loading, some research suggests that there may be a relationship between foot turnout and joint loading. Continuing relatively simple studies, like these, reveal trends which more individualized approaches can later use, accounting for individuals' anatomy to fully understand patellofemoral joint loading during the back squat.Item Support moment distribution and induced acceleration analysis of the barbell back squat(Montana State University - Bozeman, College of Education, Health & Human Development, 2020) Goodman, William Wesley; Chairperson, Graduate Committee: David Graham and James P. Becker (co-chair); Victoria Flores, Joshua Cotter, David Graham and James Becker were co-authors of the article, 'Support moment distribution during the barbell back squat at different depths and loads in recreationally trained females' submitted to the journal 'Journal of strength and conditioning research' which is contained within this thesis.; James Becker and David Graham were co-authors of the article, 'An induced acceleration analysis of the barbell back squat at different depths in trained females' submitted to the journal 'Journal of strength and conditioning research' which is contained within this thesis.The barbell squat exercise is performed in settings ranging from rehabilitation through to developing muscle size, strength and power. Unfortunately, the lower extremity coordination producing the squat is not clearly understood. This thesis involves two studies evaluating how lower limb joints and muscles coordinate varied squat performance. Study one included 19 females who performed squats at three randomized depths (above parallel, parallel, below parallel) and three loads (unloaded, 50%, 85% 1 repetition maximum). Inverse dynamics analysis revealed that peak hip and ankle extensor moments varied with load but not depth and were greatest when using 85% 1 repetition maximum. Within each depth, as load increased so did peak knee extensor moments. Peak knee extensor moments were greatest when squatting below parallel with load. Within each depth as load increased contribution of the hip increased whereas the knee decreased. Ankle contribution was only influenced by load. When squatting to deep depths with load, the contribution of the hip decreased while the knee increased. In study two, 13 females squatted to the same 3 depths using 85% of their 1 repetition maximum at each respective depth. Performance was evaluated by estimating the individual muscle force production and the individual muscle contribution to whole body acceleration using a musculoskeletal model. The gluteus maximus and adductors increased peak force to parallel while the hamstrings and rectus femoris increased to below parallel. At deep depths, the vasti decreased peak force while the hamstrings and rectus femoris increased peak force. The induced acceleration of the vasti at transition decreased with depth while the hamstrings and rectus femoris increased. Because muscles can instantaneously accelerate all joints in the body, it's possible that at transition the hamstrings accelerated the hip and knee into extension while the rectus femoris also accelerated the knee and hip into extension while the soleus accelerated the ankle and knee into extension. In conclusion, a complex coordination of the lower extremity is used performing the squat. Varied coordination indicates that depth and load specificity is important and should be taken into consideration when programming based on the status and goals of the individual.Item In-plane shear behavior of geosynthetics from bias biaxial tests using digital image correlation(Montana State University - Bozeman, College of Engineering, 2019) Schultz, Emily Christine; Chairperson, Graduate Committee: Steven PerkinsGeosynthetics are polymeric membranes used for structural reinforcement of soils in a variety of roadway and foundation applications, many of which create biaxial loading on the geosynthetic. Orthotropic linear elastic models have been used to represent geosynthetic behavior at working load levels for engineering design purposes. Typically, the models rely on index parameters obtained from test methods that do not represent the biaxial field loading conditions. Proper calibration of these models requires load-strain data obtained from tests that have controlled stress and strain boundaries such as biaxial tension tests. Previously at Montana State University, Haselton (2018) successfully used a custom biaxial device to perform biaxial tension tests on cruciform shaped geosynthetic specimens, producing a partial set of resilient elastic constants for two woven geotextiles and six biaxial geogrids. To complete the set of elastic constants by determination of the in-plane shear modulus, another mode of loading was necessary. Literature from biaxial shear tests of architectural membranes suggested cutting the cruciform shaped samples with the principal material directions on a 45-degree bias, which causes the sample to shear when the cruciform axes are unequally loaded. This test mode was successfully implemented with the existing biaxial device to determine the resilient in-plane shear modulus using an orthotropic linear elastic model. Full-field strain measurements were captured using digital imaging correlation (DIC) software available at Montana State University. DIC was shown to produce equivalent strain measurements to the mechanical instrumentation (LVDTs) used by Haselton, enabling a combined dataset. The full-field DIC strain measurements were then used to validate Haselton's assumption regarding the region of uniform strain and to identify the region of uniform strain for data collection in this thesis. DIC also showed reasonably pure biaxial tension in the cruciform samples, validating the elastic constant derivations for both Haselton and this thesis.Item Validation of high strain rate, multiaxial loads using an in-plane loader, digital image correlation, and FEA(Montana State University - Bozeman, College of Engineering, 2018) Stroili, Christopher; Chairperson, Graduate Committee: David A. MillerMontana State University's In-Plane Loader (IPL) is a machine designed to test for mechanical properties at multi-axial states of stress and strain by in-plane translation and rotation. Historically the machine has been used to characterize composite lay-ups, where applying multi-axial loads can better describe anisotropic materials. The IPL testing machine uses Digital Image Correlation (DIC) software and a stereoscopic camera system to measure strains on the surface of the test coupon by tracking a stochastic pattern applied to the gage section. The focus of this work was to test the capabilities beyond quasi-static composites testing, specifically looking to explore the feasibility of testing plastics and metals at strain rates from 10 0 to 10 3 s -1. This work explored the speed and loading capabilities of the IPL and determined a suitable coupon geometry which balances gage section area with material strength. 304 Stainless Steel was tested both on the IPL and in uniaxial tension. Experimental tensile test data was fit to a Johnson Cook strain rate sensitive constitutive model. This constitutive equation was then used with an implicit dynamic finite element analysis (FEA) model. To study the validity of high rate testing of steel in the IPL, strain from the DIC experimental data was compared with the FEA results. While the strains predicted by the FEA model varied from experimental results, a better understanding of the IPL capabilities has been achieved. Moving forward, a series of recommendations have been made so that high strain rate multi-axial testing of metals can be implemented with more robust constitutive models.Item In vitro and in vivo systems mechanobiology of osteoarthritic chondrocytes(Montana State University - Bozeman, College of Engineering, 2015) Zignego, Donald Lee; Chairperson, Graduate Committee: Ronald K. June II; Aaron A. Jutila, Martin K. Gelbke and Daniel M. Gannon were co-authors, and Ronald K. June was a corresponding author of the article, 'The mechanical microenviroment of high concentration agarose for applying deformation to primary chondrocytes' in the journal 'Journal of biomechanics' which is contained within this thesis.; Aaron A. Jutila was a main author, Bradley K. Hwang, Jonathan K. Hilmer, Timothy Hamerly, Cody A. Minor and Seth T. Walk were co-authors, and Ronald K. June was a corresponding author of the article, 'Candidate mediators of chondrocyte mechanotransduction via targeted and untargeted metabolomic measurements' in the journal 'Archives of biochemistry and biophysics' which is contained within this thesis.; Carley N. McCutchen, Jonathan K. Hilmer were co-authors, and Ronald K. June was a corresponding author of the article, 'Mechanotransduction in primary human osteoarthritic chondrocytes is mediated by metabolism of energy, lipids, and amino acids' submitted to the journal 'Arthritis and rheumatology' which is contained within this thesis.; Jonathan K. Hilmer was a co-author, and Ronald K. June was a corresponding author of the article, 'Shotgun phosphoproteomics identifies activation of vimentin, ankyrin, vam6/vpS39-like protein in primary human osteoarthritic chondrocytes after mechanical stimulation' submitted to the journal 'eLife' which is contained within this thesis.; Sarah E. Mailhiot, Timothy Hamerly, Edward E. Schmidt were co-authors, and Ronald K. June was a corresponding author of the article, 'Alterations in joint metabolomics following surgical destabilization and exercise in a novel cartilage reporter mouse model' submitted to the journal 'Annals of biomedical engineering' which is contained within this thesis.All cells are subjected to and respond to mechanical forces, but the underlying processes linking the mechanical stimuli to biological responses are poorly understood. In the joints of the body (e.g. the knee, hip, etc...) articular cartilage serves as a low friction, load bearing material and is subjected to near-constant mechanical loading. Through excessive loading of the joint, usually caused by obesity or injury, the protective articular cartilage begins to diminish, leading to the progression of osteoarthritis (OA). Osteoarthritis is the most common joint disorder in the world and is characterized by the deterioration of articular cartilage. Determining the link between cartilage deterioration and mechanical loading is one motivation that drove this research. Articular cartilage is composed of a dense extracellular matrix (ECM), a less-stiff pericelluar matrix (PCM), and highly specialized cells called chondrocytes. As the sole cell type in cartilage, chondrocytes are responsible for the healthy turnover of the ECM by creating, maintaining, and repairing the matrix. Multiple lines of evidence suggest chondrocytes can transduce mechanical stimuli into biological signals. The hypothesis for this research is that physiologically pertinent loading of chondrocytes results in a specific set of bio-signals resulting in matrix synthesis. To test this hypothesis, two unbiased, large-scale metabolomic and phosphoproteomic datasets were generated by modeling physiological compressive loading on 3D-embedded chondrocytes. To assess loading-induced changes in metabolites (e.g. small molecules representing the functional state of the cell) and proteome-wide patterns of post-translational modifications (i.e. phosphorylation), chondrocytes were encapsulated in physiologically stiff agarose, compressively loaded in tissue culture, and analyzed via liquid chromatography -- mass spectrometry (LC-MS). The results helped identify global and local biological patterns in the chondrocytes which are a direct result from mechanical loading. In addition, a novel mouse model that expresses cartilage specific bioluminescence was used to assess loading induced changes in vivo. The results from the mouse model allowed for in vivo validation and integration of the in vitro results from the metabolomic and phosphoproteomic results. To my knowledge, such research has never been done, and considerably expands the scientific knowledge of chondrocyte mechanotransduction.Item Effect of variation of member stiffness on behavior to timber bridge floor systems(Montana State University - Bozeman, College of Engineering, 1985) Riple, Arne BengtThis paper investigates the effects incurred in a bridge floor system resulting from variation in member stiffnesses. If the stiffness in one stringer is reduced, without reducing the stiffness in the other members, a higher load must be carried by the nonreduced members. The increased loading condition results in reduced capacity for the floor system. The study is accomplished using a computer simulation to analyze the member reactions in the floor system. Using a structural grid as a model for the bridge floor, a matrix solution based on the stiffness method is solved by computer. Figures are presented to show the effects on member reactions resulting from variation in stiffness and loading conditions. Results show the effects occurring in both exterior and interior stringers as well as in the floor planks. The governing effects from these members are combined to show the effects in the floor system. Reducing the stiffness in an exterior stringer results in a greater reduce tion in capacity of the floor system, compared to reduction in capacity due to reduction in an interior stringer.