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 Performance of FRP-strengthened reinforced concrete beams subjected to low temperature(Montana State University - Bozeman, College of Engineering, 2021) Ahmed, Emtiaz; Chairperson, Graduate Committee: Kirsten MattesonThe use of Fiber Reinforced Polymer (FRP) to repair and strengthen existing concrete structural elements (beams, columns, beam-column connections, and slabs) has become globally accepted and popular. FRP can be used for this application in several forms, such as externally applied wrapping, Near Surface Mounted (NSM) bars, lamination, and sheets. The strength to weight ratio of this material is one of the main criteria that makes this material approved and desired by engineers and researchers for this application. Also, FRP is corrosion resistant and requires less installation time compared to other repairing techniques such as jacketing, section enlargement, and external post tensioning. The performance of FRP repairs has been studied extensively at conventional, non-extreme temperatures; however, little research has been conducted on the performance of these repairs at cold temperatures. The research discussed herein aims to fill this gap in knowledge so that FRP repairs can be more widely used in cold temperature environments, such as for bridge repairs in the state of Montana. In this work, six beams (6 in. x 8 in., 10 ft long) were constructed and tested in four-point bending at two different temperatures (room temperature and -40 °C). For each temperature, there were three beam types: 1) a control beam, 2) a longitudinal strengthened beam, and 3) a longitudinal + transverse strengthened beam. Overall, the results showed that low temperatures have a generally positive effect on concrete strength and beam performance. The average concrete compressive strength of frozen cylinders at -40 °C was observed to be 87.18% higher than the cylinders tested at room temperature. For all beam types, the ultimate load carrying capacity of the low temperature beams exceeded the capacity of the counterpart beam tested at room temperature. Additionally, at lower temperatures the strengthened beams showed delayed FRP delamination (occurring at higher displacements). Further, the initial stiffnesses of the cold beams were found to be significantly higher than the room temperature beams. Overall, the results of this study are promising for the potential of use of FRP for repairs in cold environments and future research is warranted.Item Alkali-silica reactivity in the state of Montana(Montana State University - Bozeman, College of Engineering, 2020) Siegner, Ashton Amelia; Chairperson, Graduate Committee: Michael Berry and Kirsten Matteson (co-chair)While ASR has been documented as an issue in many states, little work has been conducted to determine the presence/potential of ASR in Montana. Thus, the primary objective of this research was to evaluate the potential for deleterious ASR in the state of Montana. In connection with this goal, a literature review was conducted to summarize the ASR practices used by neighboring state departments of transportation, as well as several federal agencies. Three potential cases of ASR damage in the state were identified and investigated using the Los Alamos Staining Method and ASTM C856. These sites included two at the Billings Logan International Airport and one at the Willow Creek Dam Spillway. Additionally, the reactivity eight aggregates, selected from various locations around the state, was tested in accordance with ASTM C1260 (Accelerated Mortar Bar Test), AASHTO T380 (Miniature Concrete Prism Tests). The literature review concluded that Canada and all other regional states explored, with the exception of North Dakota, directly addressed ASR in their material specifications, to varying degrees. The FHWA defers to individual states to determine ASR practices, while the FAA has fairly stringent specifications. The hardened concrete analyses conducted for the two Billings Logan International Airport Los sites indicated the presence of ASR in both locations; more specifically, the damage was classified as severe/Type V according to two separate criteria. The results of the Willow Creek Dam Spillway petrographic examination indicated the severity of the ASR distress observed in the spillway varied based on location, with advanced ASR detected in the ogee. This aspect demonstrated that cases of ASR in Montana do exist, and that the infrastructure in the state is susceptible to this type of failure mechanism. The results of the aggregate testing indicated that all the fine aggregates were reactive and very highly reactive according to ASTM C1260 and AASHTO T380, respectively. Two of the four coarse aggregates were innocuous according to ASTM C1260, while all of the coarse aggregates were reactive, to varying degrees, according to AASHTO T380. It was concluded that Montana's aggregates are susceptible to ASR.Item Feasibility of non-proprietary ultra-high performance concrete (UHPC) for use in highway bridges in Montana: phase II field application(Montana State University - Bozeman, College of Engineering, 2020) Scherr, Riley James; Chairperson, Graduate Committee: Michael BerryUltra-high performance concrete (UHPC) has properties far exceeding those of conventional concrete. The MDT Bridge Bureau is interested in using UHPC in field-cast joints between precast concrete deck panels. The primary objective of the research discussed herein was to further investigate and develop a non-proprietary UHPC mix developed for use in Montana. Specifically, this research (1) investigated the potential variability in concrete performance related to differences in constituent materials, (2) investigated issues related to the field batching/mixing of the these UHPC mixes, and (3) tested rebar bond strength and its effects on requisite development lengths. Throughout this research project, the different aspects used to test the UHPC performance and prepare the UHPC, further detailed in chapter 3 of this report, are mixing procedures, flow testing, specimen casting, preparation and curing procedures, compression testing, flexure testing, set time estimates, and bond strength/pullout capacity testing. Variations in the source of the constituent materials had fairly minor effect on UHPC performance. Flow generally increased with increasing aggregate moisture content, and the 7- and 28-day compressive strengths generally decreased. Adjusting the mix water to account for the varying aggregate moisture contents did not have a significant effect on flow, but it was observed to slightly increase the compressive strengths in many cases. The UHPC mixes obtained strengths exceeding 10 ksi in the first 24 hours and continued to gain strength over the duration of testing, ultimately reaching strengths of around 20 ksi at 182 days. Batch size did not have a significant effect on flow or compressive strength; however, larger scale mixes required 10% more water and HRWR in order to obtain the same performance when size was increased from 0.2 cu. ft. to 2.5 cu. ft. or larger. Flow was observed to decrease with increasing temperature, while the compressive strengths for the hottest mix were consistently the lowest. The reinforcement that met the minimum FHWA recommendations all reached maximum applied pullout stresses above the rebar yield strengths. This indicates that the FHWA embedment depth recommendations should be suitable for use in the purposed bridge closure pours with this research's developed UHPC mix.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 An investigation of a prefabricated steel truss girder bridge with a composite concrete deck(Montana State University - Bozeman, College of Engineering, 2018) Kuehl, Tyler William; Chairperson, Graduate Committee: Damon FickSteel truss girder bridges are an efficient and aesthetic option for highway crossings. Their relatively light weight compared with steel plate girder systems make them a desirable alternative for both material savings and constructability. A prototype of a welded steel truss girder constructed with an integral concrete deck has been proposed as a potential alternative for accelerated bridge construction (ABC) projects in Montana. This system consists of a prefabricated welded steel truss girder topped with a concrete deck that can be cast at the fabrication facility (for ABC projects) or in the field after erection (for conventional projects). To investigate possible solutions to the fatigue limitations of certain welded member connections in these steel truss girders, bolted connections between the diagonal tension members and the top and bottom chords of the steel truss girders were evaluated. A 3D finite element model was used to more accurately represent the distribution of lane and truckloads to the individual steel truss girders. This distribution was compared to an approximate factor calculated using an equivalent moment of inertia with expressions for steel plate girders from AASHTO. A 2D analytical model was used to investigate the fatigue strength of the bolted and welded connections for both a conventional cast in place deck system and an accelerated bridge deck system (cast integral with the steel truss girder). Truss members and connections for both construction alternatives were designed using loads from AASHTO Strength I, Fatigue I, Fatigue II, and Service II load combinations. A comparison was made between the two steel truss girder configurations and 205 ft. steel plate girder used in a previously designed bridge over the Swan River. Material and fabrication estimates suggest the cost of the conventional and accelerated construction methods is 10% and 26% less, respectively, than the steel plate girder designed for the Swan River crossing.Item Performance and design of steel pipe pile to concrete cap connections subject to seismic or high transverse loading(Montana State University - Bozeman, College of Engineering, 2016) Kappes, Lenci Robert; Chairperson, Graduate Committee: Michael Berry; Michael Berry, Jerry Stephens and Ladean McKittrick were co-authors of the article, 'Concrete filled steel tube piles to concrete pile-cap connections' in the journal 'Structures Congress 2012' which is contained within this thesis.; Michael Berry, Flynn Murray, Jerry Stephens and Kent Barnes were co-authors of the article, 'Seismic performance of concrete-filled steel tube to concrete pile-cap connections' in the journal 'ASCE Journal of Bridge Engineering' which is contained within this thesis.; Michael Berry and Jerry Stephens were co-authors of the article, 'Analysis methodology for concrete-filled steel pipe piles to concrete cap connections' which is contained within this thesis.This research investigated the seismic behavior of the connection between concrete-filled steel tube (CFT) piles and concrete pile caps. This connection is an important component of an accelerated bridge construction technique, which involves driving steel piles to a finished elevation just below the design deck level, forming a pile cap around the ends of the driven piles, reinforcing this cap, and then filling the piles and the cap formwork with concrete. This cap then serves as the support for the superstructure of the bridge. Conventional configurations of the CFT to pile cap connection often involve congested and complex reinforcing schemes, which can limit the use of this bridge support system. The research discussed herein evaluated the performance of a new detailing scheme that significantly reduces congestion and construction issues, and developed a mechanics-based analysis tool to predict load carrying capacity of this type of connection. This new reinforcing scheme uses U-shaped reinforcing bars to encircle the tip of the embedded CFT pile within the cap, which act to confine the concrete immediately around the pile and transfer the loads throughout the cap. In this research, six connection specimens with various details were tested under lateral loads until failure while monitoring applied loads and lateral displacements. As intended, five specimens experienced failure in the concrete cap, with the remaining specimen failing through plastic hinging in the CFT at the face of the cap. The focus of this test program was on characterizing the failure behavior of the concrete cap; typically, this behavior was observed to consist of crushing of the concrete adjacent to the pile near the face of the cap and at the tip of embedment, followed by yielding of the longitudinal reinforcement, and concluding with yielding of the transverse reinforcement and the formation of diagonal cracks extending from the embedded pile to the edge of the cap. Based on the results of this and a previous investigation, an analysis methodology (similar to moment-curvature analysis) was developed and evaluated. This methodology proved to be an effective means for predicting the ultimate capacity of CFT to concrete pile cap connections.Item Curvature ductility of reinforced and prestressed concrete columns(Montana State University - Bozeman, College of Engineering, 1984) Suprenant, Bruce AlanEngineers are concerned with the survival of reinforced and prestressed concrete columns during earthquakes. The prediction of column survival can be deduced from moment-curvature curves of the column section. An analytical approach is incorporated into a computer model. The computer program is based on assumed stress-strain relations for confined and unconfined concrete, nonprestressed and prestressing steel. The results of studies on reinforced and prestressed concrete columns indicate that reinforced concrete columns may be designed to resist earthquakes, while prestressed concrete columns may not. The initial reduction in moment capacity, after concrete cover spalling, of a prestressed concrete column could be as much as 50%. Analyses indicate that the bond between concrete and prestressing strand after concrete cover spalling is not critical.Item An investigation of load entry into the edge beam of a concrete hyperbolic paraboloid(Montana State University - Bozeman, College of Engineering, 1961) Thurman, Allen G.