Scholarly Work - Civil Engineering
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/3460
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Item Test of 90-Foot Post-Tensioned Concrete Girder with Unbonded Tendons(American Concrete Institute, 2021-09) Pujol, Santiago; Fick, Damon; Fargier-Gabaldón, Luis B.A full-scale post-tensioned concrete girder with unbonded tendons was tested to investigate whether, under vertical forces, a full flexural mechanism (with three hinging regions) would form, and what strand stress would be reached in that condition. The specimen was a 0.91 m (3 ft) deep T-beam with a 2.43 m (8 ft) wide flange, spanning over two supports spaced at 18.3 m (60 ft) with two 4.6 m (15 ft) cantilevers and featured a parabolic tendon profile. Transverse reinforcement to resist shear and longitudinal “mild” reinforcement were also provided. A uniformly distributed load was applied on the main span and concentrated loads were applied to the ends of the cantilevers. While the main span was loaded, the two concentrated loads on the cantilevers provided a reaction force to minimize rotations at supports. At the end of the test, the girder deflected 278 mm (10.9 in., L/65) and carried 231 kN/m (15.5 kip/ft) over the main span. A full plastic mechanism formed with hinging regions at supports and at midspan. Test results suggest the unbonded tendons nearly reached their nominal strength (fpu) and that a limit analysis is adequate for estimating the flexural strength of comparable post-tensioned girders.Item International Journal of Multiphase Flow(Elsevier BV, 2021-07) Tagliavini, Giorgia; McCorquodale, Mark; Westbrook, Chris; Corso, Pascal; Krol, Quirine; Holzner, MarkusThis study considers complex ice particles falling in the atmosphere: predicting the drag of such particles is important for developing of climate models parameterizations. A Delayed-Detached Eddy Simulation model is developed to predict the drag coefficient of snowflakes falling at Reynolds number between 50 and 2200. We first consider the case where the orientation of the particle is known a posteriori, and evaluate our results against laboratory experiments using 3D-printed particles of the same shape, falling at the same Reynolds number. Close agreement is found in cases where the particles fall stably, while a more complex behavior is observed in cases where the flow is unsteady. The second objective of this study is to evaluate methods for estimating the drag coefficient when the orientation of the particles is not known a posteriori. We find that a suitable average of two orientations corresponding to the minimum and maximum eigenvalues of the inertia tensor provides a good estimate of the particle drag coefficient. Meanwhile, existing correlations for the drag on non-spherical particles produce large errors (≈50%). A new formula to estimate snow particles settling velocity is also proposed. Our approach provides a framework to investigate the aerodynamics of complex snowflakes and is relevant to other problems that involve the sedimentation of irregular particles in viscous fluids.Item Empirical Bayes application on low-volume roads: Oregon case study(Elsevier BV, 2021-12) Al-Kaisy, Ahmed; Huda, Kazi Tahsinntroduction: This paper investigates the Empirical Bayes (EB) method and the Highway Safety Manual (HSM) predictive methodology for network screening on low-volume roads in Oregon. Method: A study sample of around 870 miles of rural two-lane roadways with extensive crash, traffic and roadway information was used in this investigation. To understand the effect of low traffic exposure in estimating the EB expected number of crashes, the contributions of both the observed and the HSM predicted number of crashes were analyzed. Results and Conclusions: The study found that, on low-volume roads, the predicted number of crashes is the major contributor in estimating the EB expected number of crashes. The study also found a large discrepancy between the observed and the predicted number of crashes using the HSM procedures calibrated for the state of Oregon, which could partly be attributed to the unique attributes of low-volume roads that are different from the rest of the network. However, the expected number of crashes for the study sample using the HSM EB method was reasonably close to the observed number of crashes over the 10-year study period. Practical Applications: Based on the findings, it can still be very effective to use network screening methods that rely primarily on risk factors for low-volume road networks. This is especially applicable in situations where accurate and reliable crash data are not available.Item The Use of Fiber-Reinforced Polymers in Wildlife Crossing Infrastructure(MDPI, 2020-02) Bell, Matthew; Fick, Damon; Ament, Rob; Lister, Nina-MarieThe proven effectiveness of highway crossing infrastructure to mitigate wildlife-vehicle collisions with large animals has made it a preferred method for increasing motorist and animal safety along road networks around the world. The crossing structures also provide safe passage for small- and medium-sized wildlife. Current methods to build these structures use concrete and steel, which often result in high costs due to the long duration of construction and the heavy machinery required to assemble the materials. Recently, engineers and architects are finding new applications of fiber-reinforced polymer (FRP) composites, due to their high strength-to-weight ratio and low life-cycle costs. This material is better suited to withstand environmental elements and the static and dynamic loads required of wildlife infrastructure. Although carbon and glass fibers along with new synthetic resins are most commonly used, current research suggests an increasing incorporation and use of bio-based and recycled materials. Since FRP bridges are corrosion resistant and hold their structural properties over time, owners of the bridge can benefit by reducing costly and time-consuming maintenance over its lifetime. Adapting FRP bridges for use as wildlife crossing structures can contribute to the long-term goals of improving motorist and passenger safety, conserving wildlife and increasing cost efficiency, while at the same time reducing plastics in landfills.Item Swimming Performance of Rainbow Trout and Westslope Cutthroat Trout in an Open-Channel Flume(2020-06) Blank, Matt D.; Kappenman, Kevin M.; Plymesser, Kathryn; Banner, Katharine M.; Cahoon, JoelWe used an open-channel flume to characterize the swimming performance of Rainbow Trout Oncorhynchus mykiss and Westslope Cutthroat Trout Oncorhynchus clarki lewisi ranging nominally in fork length from 15 to 30 cm. With an open-channel flume, we observed volitional swim performance of wild-caught Rainbow Trout and Westslope Cutthroat Trout; the fish were not coerced, prodded, or spooked into action. We also observed the maximum short-duration swim speed of the fish, providing important effective leap or velocity challenge information for the design of intentional barriers. We conducted the experiment with a consistently low water velocity challenge and characterized swim speeds by using weighted least-squares regression, revealing no evidence of a difference in swim speeds between the two species. We estimated the overall average swim speed for Rainbow Trout to be 0.84 m/s (SE = 0.02), with a 95% confidence interval of 0.79–0.89 m/s, and that for Westslope Cutthroat Trout to be 0.84 m/s (SE = 0.03), with a 95% confidence interval of 0.78–0.90 m/s. The maximum swim speeds observed were 2.72 m/s for Rainbow Trout and 3.55 m/s for Westslope Cutthroat Trout. The project results provide new information on the swimming ability of wild Rainbow Trout and Westslope Cutthroat Trout that can be used to improve fish passage or barrier design.Item Biomineralization of Plastic Waste to Improve the Strength of Plastic-Reinforced Cement Mortar(2021-04) Kane, Seth; Thane, Abby; Espinal, Michael; Lunday, Kendra; Armagan, Hakan; Phillips, Adrienne J.; Heveran, Chelsea M.; Ryan, Cecily A.The development of methods to reuse large volumes of plastic waste is essential to curb the environmental impact of plastic pollution. Plastic-reinforced cementitious materials (PRCs), such as plastic-reinforced mortar (PRM), may be potential avenues to productively use large quantities of low-value plastic waste. However, poor bonding between the plastic and cement matrix reduces the strength of PRCs, limiting its viable applications. In this study, calcium carbonate biomineralization techniques were applied to coat plastic waste and improved the compressive strength of PRM. Two biomineralization treatments were examined: enzymatically induced calcium carbonate precipitation (EICP) and microbially induced calcium carbonate precipitation (MICP). MICP treatment of polyethylene terephthalate (PET) resulted in PRMs with compressive strengths similar to that of plastic-free mortar and higher than the compressive strengths of PRMs with untreated or EICP-treated PET. Based on the results of this study, MICP was used to treat hard-to-recycle types 3–7 plastic waste. No plastics investigated in this study inhibited the MICP process. PRM samples with 5% MICP-treated polyvinyl chloride (PVC) and mixed type 3–7 plastic had compressive strengths similar to plastic-free mortar. These results indicate that MICP treatment can improve PRM strength and that MICP-treated PRM shows promise as a method to reuse plastic waste.Item Hydraulic Analysis at the Interface of the Yellowstone River and the Huntley, Montana Irrigation Diversion Fish Bypass(Montana State University, 2021-11) Johnson, Andrew; Cahoon, Joel; Zale, Al; Plymesser, Katey; Blank, MatthewThe nature-like bypass channel built to allow fish to circumvent the Huntley Diversion Dam on the Yellowstone River was constructed in 2015. A project was commissioned in 2019 to determine the effectiveness of the bypass using hydraulic modeling and fish detection techniques. During the course of the study it was observed that there may be a localized zone of high water velocity at the interface between the upstream end of the bypass and the main channel of the river -an area just upstream of the low-head dam. The concern this raises is that some fish that successfully negotiate the bypass channel may be returned directly over the dam due a difficult hydraulic condition at the interface. That observation prompted a more focused hydraulic modeling exercise as reported herein. A detailed 2-D HEC-RAS model was developed to investigate the hydraulic conditions. The model predicts localized water velocities of up to 15 ft/sec. At low river flows there appears to be adequate pathways for fish to avoid this high velocity region, but as river flow increases so does the area in which the velocity is high. From these results it is likely that, during higher river flow periods, the bypass channel may be passable, but fish may struggle to re-enter the river channel successfully. Suggested physical alterations to the site to help overcome this range from the addition of large rip rap to rerouting the upstream end of the bypass channel. AcknowledgementItem In Situ Effective Snow Grain Size Mapping Using a Compact Hyperspectral Imager(2021-02) Donahue, Christopher; Skiles, S. McKenzie; Hammonds, KevinEffective snow grain radius (re) is mapped at high resolution using near-infrared hyperspectral imaging (NIR-HSI). The NIR-HSI method can be used to quantify re spatial variability, change in re due to metamorphism, and visualize water percolation in the snowpack. Results are presented for three different laboratory-prepared snow samples (homogeneous, ice lens, fine grains over coarse grains), the sidewalls of which were imaged before and after melt induced by a solar lamp. The spectral reflectance in each ~3 mm pixel was inverted for re using the scaled band area of the ice absorption feature centered at 1030 nm, producing re maps consisting of 54 740 pixels. All snow samples exhibited grain coarsening post-melt as the result of wet snow metamorphism, which is quantified by the change in re distributions from pre- and post-melt images. The NIR-HSI method was compared to re retrievals from a field spectrometer and X-ray computed microtomography (micro-CT), resulting in the spectrometer having the same mean re and micro-CT having 23.9% higher mean re than the hyperspectral imager. As compact hyperspectral imagers become more widely available, this method may be a valuable tool for assessing re spatial variability and snow metamorphism in field and laboratory settings.Item Hydraulic characterization and removal of metals and nutrients in an aerated horizontal subsurface flow “racetrack” wetland treating oil industry effluent(Elsevier, 2021-07) Mozaffari, Mohammad-Hosein; Shafiepour, Ehsan; Mirbagheri, Seyed Ahmad; Rakhshandehroo, Gholamreza; Wallace, Scott; Stefanakis, Alexandros I.Constructed wetlands (CW) are an attractive technology due to their operational simplicity and low life-cycle cost. It has been applied for refinery effluent treatment but mostly single-stage designs (e.g., vertical or horizontal flow) have been tested. However, to achieve a good treatment efficiency for industrial effluents, different treatment conditions (both aerobic and anaerobic) are needed. This means that hybrid CW systems are typically required with a respectively increased area demand. In addition, a strong aerobic environment that facilitates the formation of iron, manganese, zinc and aluminum precipitates cannot be established with passive wetland systems, while the role of these oxyhydroxide compounds in the further co-precipitation and removal of heavy metals such as copper, nickel, lead, and chromium that can simplify the overall treatment of industrial wastewaters is poorly understood in CW. Therefore, this study tests for the first time an innovative CW design that combines an artificially aerated section with a non-aerated section in a single unit applied for oil refinery wastewater treatment. Four pilot units were tested with different design (i.e., planted/unplanted, aerated/non-aerated) and operational (two different hydraulic loading rates) characteristics to estimate the role of plants and artificial aeration and to identify the optimum design configuration. The pilot units received a primary refinery effluent, i.e., after passing through a dissolved air flotation unit. The first-order removal of heavy metals under aerobic conditions is evaluated, along with the removal of phenols and nutrients. High removal rates for Fe (96–98%), Mn (38–81%), Al (49–73%), and Zn (99–100%) generally as oxyhydroxide precipitates were found, while removal of Cu (61–80%), Ni (70–85%), Pb (96–99%) and Cr (60–92%) under aerobic conditions was also observed, likely through co-precipitation. Complete phenols and ammonia nitrogen removal was also found. The first-order rate coefficient (k) calculated from the collected data demonstrates that the tested CW represents an advanced wetland design reaching higher removal rates at a smaller area demand than the common CW systems.Item Variation of Small-Strain Shear Modulus of Unsaturated Silt under Successive Cycles of Drying and Wetting(2020-07) Khosravi, Ali; Hashemi, Amirhossein; Ghadirianniari, Sahar; Khosravi, MohammadA new framework is developed to extend an existing small-strain shear modulus (𝐺max) model to determine 𝐺max of unsaturated silty soils along different paths of the soil water retention curve (SWRC) including the scanning loops. The suitability of the proposed framework is validated against experimental results of a series of bender-element tests performed in this study and data reported in literature. Measured values of 𝐺max showed a slight hysteresis in the 𝐺max measurements along the scanning curves of the SWRC, with lower values along the wetting scanning paths. However, results indicated that the value of 𝐺max was recovered once the main drying path was reached. Results of this study also indicated that 𝐺max behavior of the silty specimen along the scanning curves was stress dependent. The model was observed to follow the experimental data along different paths of the SWRC including scanning curves.