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Articles 1 - 14 of 14
Full-Text Articles in Engineering
Reliability Of Sfrp-Strengthened Rc Bridge Columns Subjected To Blast Loads, Ahmad Alsendi, Christopher D. Eamon
Reliability Of Sfrp-Strengthened Rc Bridge Columns Subjected To Blast Loads, Ahmad Alsendi, Christopher D. Eamon
Civil and Environmental Engineering Faculty Research Publications
The reliability of reinforced concrete bridge columns strengthened with externally bonded, steel-fiber reinforced polymer fabric subjected to blast loads was investigated. Columns were modeled with a nonlinear finite element approach that considers material damage, fracture, and separation. Different concrete strengths, longitudinal reinforcement ratios, and gravity and blast load levels were considered, while uncertainties in material strength and stiffness parameters, as well as load characteristics, were incorporated in the probabilistic analysis. It was found that the use of SFRP can allow significant increases in blast load while maintaining the same level of column reliability.
Initial Assessment Of Liquefied Scrap Tire Concrete, Abdulkareem Kuaryouti, Christopher D. Eamon
Initial Assessment Of Liquefied Scrap Tire Concrete, Abdulkareem Kuaryouti, Christopher D. Eamon
Civil and Environmental Engineering Faculty Research Publications
A new approach to incorporate scrap tire material into concrete was investigated, where two reclaimed waste tire components, carbon black and fuel oil, were used to replace a portion of water. The effect of “liquid tire” content to water ratios from 5-40% on an otherwise typical concrete mix were assessed, where compressive and flexural strength, flexural toughness, modulus of elasticity, and several fresh concrete properties were determined. Results were compared to typically expected results of traditional shredded tire mixes with equivalent tire content. It was found that the liquid tire mixes experienced significantly less losses of compressive strength and workability …
Failure Sampling With Optimized Ensemble Approach For The Structural Reliability Analysis Of Complex Problems, Christopher Eamon, Kapil Patki, Ahmad Alsendi
Failure Sampling With Optimized Ensemble Approach For The Structural Reliability Analysis Of Complex Problems, Christopher Eamon, Kapil Patki, Ahmad Alsendi
Civil and Environmental Engineering Faculty Research Publications
Failure sampling is a structural reliability method based on modified conditional expectation suitable for complex problems for which reliability index-based approaches are inapplicable and simulation is needed. Such problems tend to have non-smooth limit state boundaries or are otherwise highly nonlinear. Previous studies recommended implementation of failure sampling with an extrapolation technique using Johnson's distribution or the generalized lambda distribution. However, what implementation method works best is problem dependent. The uncertainty of which approach provides best results for a particular problem limits the potential effectiveness of the method. In this study, a solution is proposed to this issue that eliminates …
Quantitative Resistance Assessment Of Sfrp-Strengthened Rc Bridge Columns Subjected To Blast Loads, Ahmad Alsendi, Christopher D. Eamon
Quantitative Resistance Assessment Of Sfrp-Strengthened Rc Bridge Columns Subjected To Blast Loads, Ahmad Alsendi, Christopher D. Eamon
Civil and Environmental Engineering Faculty Research Publications
The blast resistance of a typical reinforced concrete bridge pier column design was modeled with a nonlinear finite element approach that considers material damage, fracture, and separation. While varying concrete strength, amount of longitudinal reinforcing steel, and gravity load, the effect of applying an externally bonded steel fiber reinforced polymer (SFRP) wrapping was assessed. The presented approach uniquely quantifies column blast resistance in terms of charge weight. It was found that blast capacity was roughly linearly related to concrete strength and steel reinforcement ratio, the former of which is most influential. It was further found that a single layer of …
Load Truncation Approach For Development Of Live Load Factors For Bridge Rating, Sasan Siavashi, Christopher D. Eamon
Load Truncation Approach For Development Of Live Load Factors For Bridge Rating, Sasan Siavashi, Christopher D. Eamon
Civil and Environmental Engineering Faculty Research Publications
Various local governments have developed state-specific vehicular live load factors for bridge rating. However, a significant computational demand is often associated with such an effort. This is due to the large size of the weigh-in-motion (WIM) databases frequently used in the procedure. In this study, a method is proposed that can significantly reduce the computational cost of the analysis, while still maintaining reasonable accuracy. The proposed approach develops approximate live load random variable statistics by truncating the WIM database based on gross vehicle weight, then a complete reliability analysis is conducted to develop new live load factors that meet AASHTO-specified …
Development Of Traffic Live Load Models For Bridge Superstructure Rating With Rbdo And Best Selection Approach, Sasan Siavashi, Christopher D. Eamon
Development Of Traffic Live Load Models For Bridge Superstructure Rating With Rbdo And Best Selection Approach, Sasan Siavashi, Christopher D. Eamon
Civil and Environmental Engineering Faculty Research Publications
Reliability-based design optimization (RBDO) is frequently used to determine optimal structural geometry and material characteristics that can best meet performance goals while considering uncertainties. In this study, the effectiveness of RBDO to develop a rating load model for a set of bridge structures is explored, as well as the use of an alternate Best Selection procedure that requires substantially less computational effort. The specific problem investigated is the development of a vehicular load model for use in bridge rating, where the objective of the optimization is to minimize the variation in reliability index across different girder types and bridge geometries. …
Reliability-Based Shear Rating Of Prestressed Concrete Bridge Girders Considering Capacity Adjustment Factor, Alaa I. Chehab, Christopher D. Eamon
Reliability-Based Shear Rating Of Prestressed Concrete Bridge Girders Considering Capacity Adjustment Factor, Alaa I. Chehab, Christopher D. Eamon
Civil and Environmental Engineering Faculty Research Publications
In this study, the reliability of prestressed concrete (PC) bridge girders in the shear rating process is quantified, where the use of a simple procedure to enhance the accuracy of shear capacity evaluation for rating is evaluated. It was found that the approximate methods used in code-based procedures to develop shear resistance used for reliability calibration of the AASHTO Bridge Design Specifications and the Manual for Bridge Evaluation result in larger discrepancies in reliability than previously assumed, as well as substantially conservative shear capacity evaluation in most cases. To examine the effects of using a more accurate shear rating process, …
Long-Term Durability Of Frp Bond In The Midwest United States For Externally-Strengthened Bridge Components, Sasan Siavashi, Christopher D. Eamon, Abdel A. Makkawy, Hwai-Chung Wu
Long-Term Durability Of Frp Bond In The Midwest United States For Externally-Strengthened Bridge Components, Sasan Siavashi, Christopher D. Eamon, Abdel A. Makkawy, Hwai-Chung Wu
Civil and Environmental Engineering Faculty Research Publications
In this study, the bond strength of a typical FRP system subjected to long-term natural weathering in the Midwest United States is experimentally investigated, and the rate of degradation is estimated. To do this, the bond strength of an FRP system exposed to over fifteen years of weathering is determined with pull-off testing, and a relationship between strength reduction and exposure time is developed using regression analysis. For unweathered specimens, it was found that the attachment strength of the FRP system was governed by the concrete substrate, while for weathered specimens, the FRP system could detach by either a failure …
Cement Improved Highly Weathered Phyllite For Highway Subgrades: A Case Study In Shaanxi Province., Xuesong Mao, Carol Jean Miller, Longqi Liu
Cement Improved Highly Weathered Phyllite For Highway Subgrades: A Case Study In Shaanxi Province., Xuesong Mao, Carol Jean Miller, Longqi Liu
Civil and Environmental Engineering Faculty Research Publications
In a cost-saving move, the soft rocks composed of highly-weathered phyllites available onsite were used to fill the subgrade in the eastern Ankang section of the expressway of Shiyan to Tianshui, China. Cement admixture was used to improve the performance of the weathered phyllites. In order to determine the best mix ratio, values corresponding to compaction performance, unconfined compressive strength, and the California bearing ratio (CBR) were analyzed for variable cement content weight percentages (3%, 4%, 5%, and 6%) using test subgrade plots in the field. Field measurements of resilience modulus and deflection confirmed that the strength of the subgrade …
Experimental Investigation Of Discharge Capacity Of Labyrinth Weirs With And Without Nappe Breakers, Omer Bilhan, Emin Emiroglu, Carol J. Miller
Experimental Investigation Of Discharge Capacity Of Labyrinth Weirs With And Without Nappe Breakers, Omer Bilhan, Emin Emiroglu, Carol J. Miller
Civil and Environmental Engineering Faculty Research Publications
Labyrinth weirs provide higher discharge capacity than conventional weirs, with the ability to pass large flows at comparatively low heads. Labyrinth weirs are primarily used as spillways for dams where the spillway width is restricted. In recent years, many research investigations have considered the hydraulic performance of labyrinth weirs, particularly as dependent on the geometric features. The previous work has improved the design basis for such weirs. However, their design still requires experimentally derived and generalized performance curves. It is especially important to observe the behavior of the weir nappe to ensure the design provides hydraulic optimization and to account …
Decay Of Pressure Fluctuation In The Hyporheic Zone Around A Cylinder, Timothy Calappi, Carol J. Miller
Decay Of Pressure Fluctuation In The Hyporheic Zone Around A Cylinder, Timothy Calappi, Carol J. Miller
Civil and Environmental Engineering Faculty Research Publications
Erosion around a submerged cylinder is a well-studied problem, and is of particular interest in bridge pier scour applications. Particles erode when lift and drag forces overcome a critical threshold. These forces are typically studied from above the water-riverbed interface and are related to geometry and surficial processes. The present study maps hyporheic pressure fluctuations as they are related to surface water velocity fluctuations. Relatively, high-pressure events in the subsurface promote a destabilizing force from within the riverbed and increase the potential for the mobilization of sediment. Differential pressure transducers were fitted within a vertical cylinder in a movable bed …
Anthropogenic Impacts To The Sediment Budget Of São Francisco River Navigation Channel Using Swat, Calvin T. Creech, Rafael Brito Siqueira, James P. Selegean, Carol J. Miller
Anthropogenic Impacts To The Sediment Budget Of São Francisco River Navigation Channel Using Swat, Calvin T. Creech, Rafael Brito Siqueira, James P. Selegean, Carol J. Miller
Civil and Environmental Engineering Faculty Research Publications
The São Francisco River Basin, located in eastern Brazil, has undergone a significant amount of anthropogenic changes in the last several decades, such as agricultural expansion, irrigation activities, mining, and the construction of large dams. Together, these changes have altered the historic sediment budget and have led to an aggradation of sediments in the navigation channel, impacting the ability to efficiently ship agricultural commodities to regional ports. In an effort to aid decision makers in future waterway navigation planning, an international partnership between the Brazilian government agency CODEVASF and the US Army Corps of Engineers (USACE) was created. Through this …
Experimental Study Of Soil Water Migration In Freezing Process, Xuesong Mao, Carol J. Miller, Zhongjie Hou, Abdul Khandker
Experimental Study Of Soil Water Migration In Freezing Process, Xuesong Mao, Carol J. Miller, Zhongjie Hou, Abdul Khandker
Civil and Environmental Engineering Faculty Research Publications
Soil water migration is a significant factor in the development of subgrade ice layers in permafrost areas. The prediction of moisture inflow to the freezing zone is an important element in the design and analysis of robust highway subgrade in permafrost regions. In order to better understand moisture inflow to the freezing zone, we designed an experimental investigation to monitor the variation of water content and temperature in freezing soil. Identical experiments were conducted using three different soil types: clay, silt, and fine sand. Moisture was supplied from the sample base while the column was maintained at a constant nonfreezing …
Developing A Family Of Curves For The Hec-18 Scour Equation, Timothy Calappi, Carol J. Miller, Donald Carpenter, Travis Dahl
Developing A Family Of Curves For The Hec-18 Scour Equation, Timothy Calappi, Carol J. Miller, Donald Carpenter, Travis Dahl
Civil and Environmental Engineering Faculty Research Publications
Accurate pier scour predictions are essential to the safe and efficient design of bridge crossings. Current practice uses empirical formulas largely derived from laboratory experiments to predict local scour depth around single-bridge piers. The resulting formulas are hindered by insufficient consideration of scaling effects and hydrodynamic forces. When applied to full-scale designs, these formula deficiencies lead to excessive over prediction of scour depths and increased construction costs. In an effort to improve the predictive capabilities of the HEC-18 scour model, this work uses field-scale data and nonlinear regression to develop a family of equations optimized for various non-cohesive soil conditions. …