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- Title
- Parking Demand Forecasting Using Asymmetric Discrete Choice Models with Applications
- Creator
- Zhang, Ji
- Date
- 2023
- Description
-
Using discrete choice models to forecast travelers parking location choice has been a branch of parking demand research for many years. The...
Show moreUsing discrete choice models to forecast travelers parking location choice has been a branch of parking demand research for many years. The most used discrete choice models have fairly simple mathematical expressions, such as the probit and logit models. The application of simple models helps release the computational burdens brought by parameter estimation tasks in practice, but the cost is the unwanted properties of classic models such as the “symmetry property” that we argue is often undesirable in many fields. To some extent, the symmetry property of related models limits the shape of curves that makes the model fitting less flexible technically. This study addresses the following question: “Can discrete choice models with asymmetry property outperform classic models with symmetry property in forecasting travelers’ parking location choices?” The contributions of this study include: (1) providing a new perspective of using asymmetric discrete choice models to explain and forecast individual’s parking location choice; and (2) completing the travel demand forecasting process from choices of the destination zone centroid to the parking location, enabling parking choice forecasting. This provides a generalized framework to calibrate and validate asymmetric discrete choice models with the field observed parking facility-specific arrival profile data integrated into a large-scale, high-fidelity regional travel demand model. Further, an experimental study is conducted to compare the performance of the proposed asymmetric discrete choice models in the parking demand forecasting framework. The results suggest that asymmetric discrete choice models for individual’s parking choice modeling outperform the symmetric discrete choice models such as the logit models owing largely to their flexibility of parameter fitting and training using the available dataset.
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- Title
- Evaluation of Bridge Abutment Slope Protection at Stream Crossings
- Creator
- Wang, Peng
- Date
- 2023
- Description
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Extensive research has revealed that scour and flooding contribute to over 50% of bridge failures in the United States, with scour-induced...
Show moreExtensive research has revealed that scour and flooding contribute to over 50% of bridge failures in the United States, with scour-induced failures alone causing the collapse of 20-100 over-water bridges annually out of a total population of approximately 504,000 bridges. Within Wisconsin, a significant number of bridges, specifically over 1200, have been identified as scour-critical, with 200 of them experiencing slope instability issues.This study focuses on the problematic bridge sites in Wisconsin, particularly examining the underperformance of abutment slopes. To identify and document these problematic bridges, a comprehensive survey was conducted, followed by site visits. Subsequently, a thorough Limit Equilibrium Method (LEM) simulation was carried out based on an investigated bridge. The simulation results indicate that the infiltration of water into the slope berm areas significantly decreases slope stability due to seepage forces. Furthermore, the absence of riprap toe protection can result in overall slope failure. The implementation of concrete pouring to address riprap scoring has proven unreliable, leading to frequent failures.Additionally, simulations were performed for grouted riprap, slope walls, grouted tiebacks, and piles. The results demonstrate their potential to enhance slope safety, with their suitability requiring careful evaluation. Notably, a simulation comparing a 1:2 slope design with a 1:1.5 slope inclination reveals that the former significantly improves slope safety.In Chapter 5, a comprehensive life cycle cost analysis is conducted, comparing the 1:2 slope design to the 1:1.5 design. The analysis reveals that the 1:2 design method is more cost-effective over a 60-year study period.In conclusion, this research provides valuable insights into the assessment and mitigation of abutment slope protection issues in Wisconsin. The findings emphasize the importance of considering seepage forces, appropriate riprap installation, and alternative stabilization measures together with a comprehensive life cycle cost analysis. The research contributes to enhancing slope safety and informs decision-making processes for bridge design and maintenance.
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- Title
- Characterization of Novel Concrete Formulations: High-Volume Fly Ash for Precast Industry Use and Non-Proprietary UHPC
- Creator
- Ordillas, Kurt Andrew
- Date
- 2024
- Description
-
The use of high-volume fly ash concretes can be challenging for high-early strength applications, such as in precast construction, largely due...
Show moreThe use of high-volume fly ash concretes can be challenging for high-early strength applications, such as in precast construction, largely due to potential delays in strength gain resulting from relatively lower heats of hydration of the underlying binder formulations. Considering that the use of higher levels of available fresh or landfilled fly ash as a replacement for traditional ordinary Portland cement (OPC) could result in more sustainable mix designs, a framework to develop novel, high-volume fly ash mixes with optimized dosages of commercial grade gypsum and accelerating admixtures to enhance early-age strength performance. Early-age mechanical properties such as compressive strength, modulus of rupture, and modulus of elasticity were evaluated starting within 24 hours of specimen preparation. Experimental test results were then characterized and subsequently analyzed relative to current design provisions to highlight the best performing trial mixes (with respect to the early-age strength target) and cases where current design provisions are either unconservative or overly-conservative with respect to the test data. Additionally, thermal properties of concrete produced with fly ash were tested with two different curing environments, along with using code equations to determine if high volume fly ash provides a higher thermal resistance compared to OPC concrete. Wrapping up cementitious replacement with non-proprietary ultra high-performance concrete (UHPC) for transportation structures. Then reproducing mixtures to ensure target compressive strength values could be reached. Followed by increasing batch size to a larger quantity using a large mixer to create full-size specimens.
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