Flood Disaster Resilient Bridge Structures For Sustainable Bridge Management Systems

Extreme weather events are occurring at an increasing ferocity and frequency. Floods are the most comand damaging natural disaster. More than 4,400 occurrences of flood disasters have been reported globally between 1900 and 2016. As a result, around seven million people were killed and millions more were displaced. Climate impacts are expected to intensify weather related flooding events, and sea level rise expected worldwide will increase the risk of coastal disasters. Transportation infrastructure, vital to the economy and society of every country, is especially prone to the inland and coastal floods. Bridge structures are under the constant threat of these natural disasters. Superstructures can be washed away due to lateral forces generated by floodwater. Floodwater can also accelerate scouring around bridge piers, which often contributes to bridge failures. This research used the results of an extreme flood simulation conducted by the Center for Advanced Infrastructure Technology at the University of Mississippi. A flood inundation model was implemented for an extreme flood scenario at a floodplain site of Little Tallahatchie River in Northern Mississippi that featured surface transportation corridor sites and other infrastructure assets. Geospatial analysis of flood inundation mapping and simulation results shothat total flood inundation covered an area of 22.46 sq mi2 (58.16 sq km2) in the floodplain, where maximum floodwater depth reached up to 34.19 ft (10.42 m) within the inundation area. The results of the extreme flood simulation were used for assessing structural integrity of a bridge structure subject to lateral floodwater forces, with primary focus on the superstructure. A Three Dimensional-Finite Element model of US-51 Highway bridge, located in the floodplain site, was developed for flood impact analysis considering bridge girder-deck superstructure, bearings, pile caps and piers. The numerical results of finite element simulation shothat the bridge superstructure displaced 2.42 m under the lateral hydrodynamic force of floodwater. The dowel bars inserted at the bottom of each girder end through bearing to the top end of pile cap, failed in shear against lateral floodwater forces. This would lead to the failure of US-51 Highway bridge superstructure if an extreme flood event occurs in real life. A framework for structural integrity assessment of bridge structures is presented with Flood Resiliency Index. Recommendations for design enhancements and hardening of bridges are discussed for flood disaster resilience. An enhanced geospatial decision support system is recommended considering “vertical underclearance” criteria for bridge superstructure height above the channel and “flood probability” related to flood occurrence in 10, 50, 100, 500 and 1,000 years. These flood resilience parameters are missing from the traditional bridge management system (BMS) framework. Enhancing the current practice of BMS is proposed using optimization based prioritization of flood disaster vulnerable bridges, which considers vertical underclearance criteria, flood disaster risk probability and life cycle cost analysis. For this purpose, a Flood Vulnerability Rating (FVR) is proposed on a scale of 1 (catastrophic risk) to 6 (very low risk). The FVR scale was used for a case study of 270 bridges on major rivers in the state of Mississippi, which were analyzed using an optimization objective function to maximize benefits considering reconstruction/hardening costs and indirect benefits (cost avoidance from traffic disruption and economic loss related to bridge failure). Based on the present-worth life cycle analysis, total life cycle costs for the agency’s pre-planned bridge hardening for flood resilience was 59.3% less than the case of no hardening of the same bridge. This dissertation advances flood risk assessment and resilience management methodologies for transportation infrastructure in the United States and across the globe

Geospatial Assessment of Sustainable Built Infrastructure Assets and Flood Disaster Protection

This research was initiated with a review and synthesis of infrastructure related to city and urban growth, built infrastructure to meet transportation needs and travel demand, and role of mass transit in reducing adverse impacts on the environment and greenhouse gas emissions. Floods are the most frequently occurring natural disaster in the world, which so far claimed millions of lives and resulted in billion-dollar economic costs. Built infrastructure assets in urban and rural areas are not spared from floods\u27 aftermath. A major motivation for this thesis was the 2011 megaflood disaster of Thailand which devastated the green campus of Asian Institute of Technology or AIT located north of Bangkok, a prominent higher education institution in Asia. AIT Campus was inundated with flood water for several weeks in late October and most of November 2011. The primary objective was to develop a geospatial decision support system for flood disaster protection of AIT using spaceborne remote sensing satellite imagery. Pre-flood 1-m IKONOS imagery of the campus area was used to create planimetrics and geospatial infrastructure inventory. Ground truth measurements along with site inspection photos facilitated further flood impact analysis and creation of a detailed flood depth map of the entire AIT Campus. Post-flood 1-m IKONOS imagery was used to estimate existing dike\u27s top width. The imagery-based planimetric of the dike and related cross-section data provided by AIT were used to conduct stability analyses of a proposed raised dike system. Other flood protection strategies proposed in this study include concrete and composite sheet pile flood wall design. Value engineering analysis was implemented to evaluate these flood wall protection alternatives for AIT Campus. Based on comprehensive present worth life cycle cost analysis conducted over 50-year performance period, the least costly composite fiber-reinforced plastic sheet pile flood wall system was recommended to protect AIT Campus from future floods at US$ 1.71 million per km. Further recommendations for future flood protection include: (1) elevated AIT access roads and other campus area roads using composite sheet pile retaining walls and culverts and (2) one or more buildings protected by composite sheet pile peripheral enclosures for emergency management applications

Opioid Misuse Prior to Incarceration Among Incarcerated Men Nearing Release from Prison

One hundred and seventy-five male inmates with a history of opioid misuse participated in Wisconsin’s residential substance abuse treatment programs. Nearing release, inmates completed surveys to report demographics, three life stressors (health, money, family), and two forms of opioid misuse (prescription opioid/opiate pain medications and heroin) during the year before incarceration. ANCOVAs illustrated that age and education were not associated with either prescription pain medication misuse or heroin use, but ethnicity was associated with heroin use, with Black inmates reporting less than White or other ethnicities. Multiple regression analyses comparing the three life stressors found that only money stressors were significantly associated with both forms of opioid misuse

Rheological and mechanical properties of cycloolefin copolymer/organoclay nanocomposites

In this study, structural, rheological and mechanical properties of cycloolefin copolymer/organoclay nanocomposite films were investigated in detail. A maleic anhydride grafted polyethylene was used as conventional compatibilizer. In a series of samples, poly(ethylene-co-1-octene) copolymer was also used as a secondary component in the sample formulations. Microstructural features of the samples and clay dispersion into the polymer phase were characterized by X-ray diffraction and scanning electron microscopy studies. Physical properties of the samples were examined with the melt rheology and dynamic mechanical analysis tests. Highly transparent films with the intercalated nanocomposite structure were successfully obtained. It was found that the poly(ethylene-co-1-octene) enhances the organoclay dispersion into polymer phase and the related physical properties of the samples. Some structural properties of the samples such as the critical volume fraction of organoclay (phi(p)) and aspect ratio (A(f)) were quantified with the experimental data obtained from the rheological and mechanical measurements. Critical volume fraction of organoclay at the percolation threshold was determined as 0.018 based on the rheological measurements. The Halpin-Tsai micro-mechanical model for composite materials was employed to determine dispersion of organoclay layers. The aspect ratio of organoclay tactoids was found to be about 12-15 based on the both rheological and micro-mechanical modeling

Rheological behavior of cycloolefin copolymer/graphite composites

In this study, morphological and rheological properties of cycloolefin copolymer (COC)/graphite composites prepared in a twin screw extruder by using various amounts of graphite (G) and expanded graphite (EG) were investigated in detail. Rheological behaviors of the samples were measured in a dynamic oscillatory rheometer in the melt state. Rheology data were analyzed in different ways in order to quantify the microstructural features which indicate the solid-state physical properties of the composite materials. In the linear viscoelastic region, increasing of storage modulus (G') with the filler amount and the van Gurp-Palmen plots were used to determine the percolation threshold which is the critical filler amount for the physical network formation by the G sheets. Percolation threshold values were found to be about 21.5 phr and 3.8 phr for the G- and EG-loaded samples, respectively. Microstructures of the samples which include quite higher amount of filler than the percolation were observed in a scanning electron microscopy. It was found that the sheets of pristine G maintained their original stack form while the EG was successfully dispersed in the COC phase and formed three dimensional house-of-card structures without a compatibilizer. POLYM. ENG. SCI., 52:2645-2653, 2012. (C) 2012 Society of Plastics Engineer

Quantifying microstructure, electrical and mechanical properties of carbon fiber and expanded graphite filled cyclic olefin copolymer composites

In this study, micro-structural features and physical properties of cyclic olefin copolymer composites filled with different amounts of carbon fiber (CF) and expanded graphite (EG) were studied. The electrical percolation for the CF and EG were found to be 30 phr (volume fraction of 0.142) and 20 phr (volume fraction of 0.083), respectively. It was also found that the electrical conductivity of double-filler composites was higher than those of single-filler counterparts at a particular filler amount which implied that more conduction pathways were formed via the connection points of CF rods and EG sheets into the structure. (C) 2014 Elsevier Ltd. All rights reserved

Rheological and electrical properties of carbon black and carbon fiber filled cyclic olefin copolymer composites

In this study, morphological, rheological and electrical properties of cyclic olefin copolymer (COC)/carbon black (CB) and COC/carbon fiber (CF) composites were investigated. Rheological measurements indicated that the CB was more effective filler than the CF to improve the viscoelastic parameters such as melt elasticity and dynamic viscosity of samples because of relatively higher surface area and nano size of CB particles. Based on the improvement in melt elasticity of samples depending on the type and amount of filler, the first rheological percolation threshold, the critical filler amount to stepwise change the rheological behavior of composites, were determined to be 9.4 and 15 phr for the CB and CF, respectively. It was also found that the local and continuous agglomeration of CB particles predicted by the Kerner-Nielsen method began at the filler amount of 10 and 30 phr, respectively. The electrical conductivity measurement performed by an impedance spectroscopy exhibited that the electrical percolation was about 15 phr for both fillers. Maximum electrical conductivity vales of 10(-2) and 10(-1) S/cm were obtained by introducing of 40 phr of CB and CF, respectively. (C) 2014 Elsevier Ltd. All rights reserved

Effects of size and shape originated synergism of carbon nano fillers on the electrical and mechanical properties of conductive polymer composites

In this study, microstructural features, mechanical properties, and electrical conductivity behaviors of thermoplastic composites prepared by using of cyclic olefin copolymer (COC) as matrix and various types of carbon nano materials, expanded graphite (EG), carbon nanofiber (CNF), and multi walled carbon nanotubes (CNT) as conductive fillers were investigated. Effects of using of double and triple filler combinations on the electrical properties of composites were also quantified in detail by measuring the bulk resistance of samples under alternating current with an impedance spectrometer. The electrical percolation values of fillers were found to be 20, 10, and 5 phr for the series of composites prepared with the EG, CNF, and CNT, respectively. It was obtained that the bulk resistances of percolated samples were dramatically decreased from 10(14) ohm.cm to 10(3)-10(4) ohm.cm. On the other hand, it was also found that the using of double and triple filler combinations provided much lower (about 10(1) ohm.cm) bulk resistance which corresponded to higher conductivity values than the highly filled composites including of 30 and 40 phr of EG. Based on the DMA measurements and the quantifying of elastic modulus values of composites in the rubbery region, it was found that the reinforcing effects of carbon nano fillers on the elastic modulus of composites decreased in the order of CNT>CNF>EG, depending on the aspect ratio (A(f)) values of fillers into the matrix. (c) 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42313

Quantifying Structural and Solid-State Viscoelastic Properties of Poly(propylene) (PP)/Poly(oxymethylene) (POM) Blend Films

In this study, isotactic poly(propylene) (PP)/poly(oxymethylene) (POM) blend films, including of POM as minor phase in the range of 10-30 wt%, are prepared in a twin screw extruder equipped with a slit-die and cast film haul-off unit. It is found that the blend films show -characteristic immiscible matrix-droplet morphology. Short-term uniaxial tensile creep behaviors of films imply that the introducing of POM significantly improves the elastic modulus and decreases the total creep strain of PP/POM blends. Creep tests are also performed at various temperatures and long-term deformations of samples are predicted by applying of time-temperature superposition principle and the Findley model. It is found that the presence of POM domains into PP matrix enhances the creep resistance of PP especially at high temperatures. It is concluded that the PP-rich PP/POM blend films show much lower short and long-term creep strains compared to PP

Effect of the comonomer content on the solid-state mechanical and viscoelastic properties of poly(propylene-co-1-butene) films

In this study, we quantified the thermal and solid-state mechanical and viscoelastic properties of isotactic polypropylene (i-PP) homopolymer and poly(propylene-1-butene) copolymer films having a 1-butene ratio of 8, 12, and 14 wt %, depending on the comonomer content. The uniaxial tensile creep and stress-relaxation behaviors of the samples were studied in a dynamic mechanical analyzer at different temperatures. The creep behaviors of the samples were modeled with the four-element Burger equation, and the long-term creep strains were predicted with the time-temperature superposition method. The short-term mechanical properties of the samples were also determined with tensile and impact testing at room temperature. We found that the Young's modulus and ultimate strength values of the samples decreased with increasing amount of 1-butene in the copolymer structure. On the other hand, the strain at break and impact strength values of the samples improved with increasing amount of 1-butene. Creep analysis showed that i-PP exhibited a relatively lower creep strain than the poly(propylene-co-1-butene)s at 30 degrees C. However, interestingly, we discovered that the temperature increase resulted in different effects on the creep behaviors. We also found that short-chain branching improved the creep resistance of polypropylene at relatively high temperatures. (c) 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46350