Theses and Dissertations at Montana State University (MSU)
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Item Concrete-filled steel tube to concrete pile cap connections: verification of analysis/design methodologies(Montana State University - Bozeman, College of Engineering, 2023) Cota, Cash Daniel; Chairperson, Graduate Committee: Michael BerryThis research project focuses on the structural behavior of concrete-filled steel tube (CFST) to concrete pile cap connections, a critical component in many Montana bridges. A series of four experimental pile cap connection specimens were designed and tested to assess the influence of key parameters such as specimen scale, concrete strength, and the incorporation of U-bars on the overall connection performance. The findings from this research revealed that all specimens, barring the specimen with U-bars, displayed consistent moment-drift responses, damage progression, and failure mechanisms within the concrete cap. The inclusion of U-bars notably increased the connection capacity by about 60%, altering the failure mechanism to a plastic hinge formation in the CFST pile. Additionally, the study validated the efficacy of a novel moment-rotation methodology for predicting the capacity of cap connections, with an average measured-to-predicted ratio of 0.95 and a coefficient of variation of 10%. However, this methodology showed a tendency to overpredict capacities in connections without U-bars and underpredict in those with U-bars. Overall, this research provides valuable insight into the behavior of these critical connections under diverse conditions and demonstrates the efficacy of the moment-rotation methodology.Item Experimental and analytical investigation of masonry infill and confined masonry wall assemblies(Montana State University - Bozeman, College of Engineering, 2017) Johnson, Maxim Gordon; Chairperson, Graduate Committee: Damon FickMasonry has the benefit of strength and ease of construction but lacks the ability to resist lateral forces due to its brittle nature. However, with the addition of concrete confining frames to plain masonry walls, additional strength and ductility can be attained. Two such confinement systems include masonry infill and confined masonry walls. Currently, masonry infill assemblies are the most common form of lateral force resisting systems in countries where access to more traditional concrete and steel materials is limited. However, recent studies have stated that confined masonry provides improved performance because of the bond between the concrete and brick. This thesis presents an investigation of the behavior of both types of concrete confinement methods and identifies advantages of each system with regards to strength, ductility, and performance during strong ground motion events. To accomplish this objective, 1/3-scale specimens were constructed and tested in direct shear to determine the load-displacement response for both masonry infill and confined masonry walls and compared with results of each type of concrete confinement technique as compared to a plain masonry specimen. The masonry infill wall strength was 35% larger and deflected ten times more than the plain masonry wall at peak load. The confined masonry showed 80% more strength capacity; however, only deflected 2.5 times more than the plain masonry wall at peak load. The test results were incorporated into analytical models that approximated the load displacement response observed during the tests. The models were used to perform a nonlinear push-over analysis on a reduced scale 5-story building damaged by the Nepal earthquake. The first story walls of the confined masonry model failed at a base shear that was 27% larger than the masonry infill model. First story drifts were 64% larger in the masonry infill model. This supports the general observation that each wall has merit in a specific design scenario. Masonry infill walls may be preferred in for designs where energy dissipation may be critical. On the strength side, confined masonry walls may be preferred where strength is preferred over ductility.Item Damage characterization of fiber reinforced composite materials by means of multiaxial testing and digital image correlation(Montana State University - Bozeman, College of Engineering, 2017) Jette, Joseph Terrance; Chairperson, Graduate Committee: Douglas S. CairnsComposite materials offer a unique quality to improve structural designs. Now, not only can a structure's geometry be designed, composite materials offer the engineer the ability to design the layup of the material and, in turn, control some of its structural properties. While this feature of composite materials is appealing, it also poses issues for all processes involved in its design. One of the primary issues is that characterization of these materials in different orientations is often difficult and expensive. Due to composite materials' anisotropy, heterogeneity, and variability, their constitutive and damage behavior remain poorly understood. Often due to this misunderstanding, designs that use composite materials undergo a lengthy, difficult, and expensive procedures to produce the final product. Part of these procedures is the finite element modeling and simulation of designed components which requires accurate material response data. As modeling capabilities improve, provided the proper material damage response modeling data, damage models offer the ability to predict the damage response of designs. The ability to accurately predict damage responses in structures is a primary contributor to a design's development time and its overall success. In this study, multiaxial testing via the Montana State University In-Plane Loader was performed on two carbon fiber epoxy prepreg material systems. This testing was performed to determine the usefulness of digital image correlation and multiaxial testing as a means of characterizing composite materials' damage responses and to produce data capable of informing and validating damage models. The combination of digital image correlation and multiaxial testing provided dense experimental results that may prove useful to qualitatively and quantitatively inform, validate, and enhance computer finite element modeling and analysis.Item A theoretical design comparison of a structural frame in prestressed and conventional reinforced concrete(Montana State University - Bozeman, College of Engineering, 1956) Teoman, MeteItem Experimental testing of a saddle type hyperbolic paraboloid using three different load conditions(Montana State University - Bozeman, College of Engineering, 1960) Nottingham, DennisItem Preliminary analysis and hanger adjustment of tied arch bridges(Montana State University - Bozeman, College of Engineering, 1984) Beyer, William EdwardPreliminary design of a tied arch bridge is complex due to the many possible parameters of the problem. After obtaining a design the minimization of dead load moment is an important consideration. Similarly, obtaining proper tensions in the hangers of a tied arch bridge is very important, to prevent overstressing of the arch. By using matrix structural analysis, the effects of certain parameters upon tied arch behavior are investigated. The parameters include rise to span ratio, hanger spacing, ratio of areas of rib and tie, and ratio of moments of inertia of rib and tie. The geometry of an existing span was used for analysis. The results of the parametric study are portrayed graphically for a range of the parameters. Methods for analysis of dead load moment and hanger tension adjustment are developed. Finally a preliminary design example is considered.