Structural Characterization of UHPC Waffle Bridge Deck and Connections, TR-614, 2014

The AASHTO strategic plan in 2005 for bridge engineering identified extending the service life of bridges and accelerating bridge construction as two of the grand challenges in bridge engineering. These challenges have the objective of producing safer and more economical bridges at a faster rate with a minimum service life of 75 years and reduced maintenance cost to serve the country’s infrastructure needs. Previous studies have shown that a prefabricated full-depth precast concrete deck system is an innovative technique that accelerates the rehabilitation process of a bridge deck, extending its service life with reduced user delays and community disruptions and lowering its life-cycle costs. Previous use of ultra-high performance concrete (UHPC) for bridge applications in the United States has been considered to be efficient and economical because of its superior structural characteristics and durability properties. Full-depth UHPC waffle deck panel systems have been developed over the past three years in Europe and the United States. Subsequently, a single span, 60-ft long and 33-ft wide prototype bridge with full-depth prefabricated UHPC waffle deck panels has been designed and built for a replacement bridge in Wapello County, Iowa. The structural performance characteristics and the constructability of the UHPC waffle deck system and its critical connections were studied through an experimental program at the structural laboratory of Iowa State University (ISU). Two prefabricated full-depth UHPC waffle deck (8 feet by 9 feet 9 inches by 8 inches) panels were connected to 24-ft long precast girders, and the system was tested under service, fatigue, overload, and ultimate loads. Three months after the completion of the bridge with waffle deck system, it was load tested under live loads in February 2012. The measured strain and deflection values were within the acceptable limits, validating the structural performance of the bridge deck. Based on the laboratory test results, observations, field testing of the prototype bridge, and experience gained from the sequence of construction events such as panel fabrication and casting of transverse and longitudinal joints, a prefabricated UHPC waffle deck system is found to be a viable option to achieve the goals of the AASHTO strategic plan.

07043-017 North Fork Maquoketa Final Report

The North Fork Maquoketa River Headwaters (NFMRH) has been identified as impaired by nutrients, episodic slugs of ammonia and sediment. The NFMRH TMDL plan calls for a "phasing approach" to managing water quality when the origin is non-point source contaminants. This project will address phase 1 using a performance reward program for targeted cooperators to improve environmental index scores using cost-share, EQIP practices and flexible management alternatives. Pre-project assessments suggest that rewards should target refined management of erosion-prone fields and farms with livestock populations, which contribute to the P and N loads responsible for fertilizing filamentous algae blooms that depress dissolved oxygen concentrations in the NFMRH. The Phosphorus Index, Soil Conditioning Index and cornstalk nitrate test will be used by producers to determine effective alternatives, such as no-till planting, to reduce nutrient and sediment delivery. These evironmental indexes will be especially useful for livestock producers in the livestock dense watershed. This project will extend a NRCS-sponsored Conservation Innovation Grant currently offered to producers in the Coffee Creek sub-watershed to a three-year, watershed-wide effort that will be necessary to make significant improvements in environmental management.

Lack of association between beta-herpesvirus infection and bronchiolitis obliterans syndrome in lung transplant recipients in the era of antiviral prophylaxis.

BACKGROUND: Cytomegalovirus (CMV), human herpesvirus-6 and -7 (HHV-6 and -7) are beta-herpesviruses that commonly reactivate and have been proposed to trigger acute rejection and chronic allograft injury. We assessed the contribution of these viruses in the development of bronchiolitis obliterans syndrome (BOS) after lung transplantation. METHODS: Quantitative real-time polymerase chain reaction of bronchoalveolar lavage samples were performed for CMV, HHV-6 and -7 in a prospective cohort of lung transplant recipients. A time-dependent Cox regression analysis was used to correlate the risk of BOS and acute rejection in patients with and without beta-herpesviruses infection. RESULTS: Ninety-three patients were included in the study over a period of 3 years. A total of 581 samples from bronchoalveolar lavage were obtained. Sixty-one patients (65.6%) had at least one positive result for one of the beta-herpesviruses: 48 patients (51.6%) for CMV and 19 patients (20.4%) for both HHV-6 and -7. Median peak viral load was 3419 copies/mL for CMV, 258 copies/mL for HHV-6, and 665 copies/mL for HHV-7. Acute rejection (>or=grade 2) occurred in 46.2% and BOS (>or=stage 1) in 19.4% of the patients. In the Cox regression model the relative risk of acute rejection or BOS was not increased in patients with any beta-herpesviruses reactivation. Acute rejection was the only independently associated risk factor for BOS. CONCLUSIONS: In lung transplant recipients receiving prolonged antiviral prophylaxis, reactivation of beta-herpesviruses within the allograft was common. However, despite high viral loads in many patients, virus replication was not associated with the development of rejection or BOS.

Anàlisi i quantificació de les accions i el temps de joc en l'hoquei sobre patins en equips de l'OK Lliga

Quantificar les variables temporal, les accions tècniques i els desplaçaments dels jugador al llarg de la competició proporciona una informació excel·lent per deduir les càrregues físiques i fisiològiques a les que estan sotmesos. Per aquest estudi es van visualitzar 4 partits de la Copa del Rei 2012. Es va enregistrà sistemàticament les dades en fulls de registre. Les principals dades analitzades van ser: temps total, temps real, temps de pausa, temps d’acció i relació entre el temps d’acció i el temps de pausa (densitat de treball). També es va analitzar: les incidències reglamentaries, les accions tècniques del jugador i els desplaçaments del jugador. El 45% de les accions es van produir entre 0 i 30s, i el promig d’interval de participació va ser 19:29s ±2:09. Més del 50% de les pauses es van produir entre 11s i 30s, i el promig d’interval de pausa va ser de 24:57s. Aquest va determinar que la densitat de treball era 1:1.3. Aproximadament el 70% de les incidències reglamentàries van ser faltes d’equip I tècniques. Van haver-hi 56 conduccions, 10 driblins, 12 remats, (3 xuts, 2 punxades/escopides, 5 remats de primeres i 2 arrossegades) i 80 passades. Finalment, en un partit el 42,23% dels desplaçaments van ser a baixa intensitat, el 27,02% van ser a intensitat mitjana i el 30,75% van ser a alta intensitat. A més a més, el 81,90% dels desplaçaments a alta intensitat van durar de 0s a 5s, el 54,56% a intensitat mitjana van durar de 6 a 10 s. I el 49,32% a intensitat baixa també van durar 6s a 10s. L’hoquei sobre patins és un esport en el que hi predominen els esforços intermitents a gran intensitat i de curta durada amb una important sol·licitació de la via anaeròbica alàctica. Analitzar la dimensió temporal, les accions tècniques i els desplaçaments dels jugador durant la competició permet estimar les exigències físiques i requeriments energètics, i aquest faciliten l’elaboració d’entrenaments més específics.

Assessment of Nondestructive Testing Technologies for Quality Control/Quality Assurance of Asphalt Mixtures, TR-653, 2015

Asphalt pavements suffer various failures due to insufficient quality within their design lives. The American Association of State Highway and Transportation Officials (AASHTO) Mechanistic-Empirical Pavement Design Guide (MEPDG) has been proposed to improve pavement quality through quantitative performance prediction. Evaluation of the actual performance (quality) of pavements requires in situ nondestructive testing (NDT) techniques that can accurately measure the most critical, objective, and sensitive properties of pavement systems. The purpose of this study is to assess existing as well as promising new NDT technologies for quality control/quality assurance (QC/QA) of asphalt mixtures. Specifically, this study examined field measurements of density via the PaveTracker electromagnetic gage, shear-wave velocity via surface-wave testing methods, and dynamic stiffness via the Humboldt GeoGauge for five representative paving projects covering a range of mixes and traffic loads. The in situ tests were compared against laboratory measurements of core density and dynamic modulus. The in situ PaveTracker density had a low correlation with laboratory density and was not sensitive to variations in temperature or asphalt mix type. The in situ shear-wave velocity measured by surface-wave methods was most sensitive to variations in temperature and asphalt mix type. The in situ density and in situ shear-wave velocity were combined to calculate an in situ dynamic modulus, which is a performance-based quality measurement. The in situ GeoGauge stiffness measured on hot asphalt mixtures several hours after paving had a high correlation with the in situ dynamic modulus and the laboratory density, whereas the stiffness measurement of asphalt mixtures cooled with dry ice or at ambient temperature one or more days after paving had a very low correlation with the other measurements. To transform the in situ moduli from surface-wave testing into quantitative quality measurements, a QC/QA procedure was developed to first correct the in situ moduli measured at different field temperatures to the moduli at a common reference temperature based on master curves from laboratory dynamic modulus tests. The corrected in situ moduli can then be compared against the design moduli for an assessment of the actual pavement performance. A preliminary study of microelectromechanical systems- (MEMS)-based sensors for QC/QA and health monitoring of asphalt pavements was also performed.

The role of neutrophils upon leishmania major infection

Les neutrophiles constituent la première ligne de défense contre un grand nombre de pathogènes. Après infection avec Leishmania major, les neutrophiles migrent rapidement et massivement au site d'infection par le parasite. Les neutrophiles sont d'importants acteurs dans l'orchestration de la réponse anti-Leishmania, via la sécrétion de nombreuses cytokines, chimiokines et composés stockés dans leurs granules. De plus, les neutrophiles interagissent avec les cellules présentatrices d'antigènes, telles que les cellules dendritiques et en conséquences contribuent au développement de la réponse adaptative. A ce jour, l'impact des neutrophiles sur 1'activation des cellules dendritiques et les possibles conséquences de l'interaction neutrophiles avec ces dernières sur l'évolution de la maladie suite à l'infection avec L. major reste peu connu. Ainsi, nous avons dans un premier temps investigué l'influence des neutrophiles sur 1'activation des cellules dendritiques in vitro. Suite à cela, nous avons analysé le rôle des neutrophiles sur 1'activation des cellules dendritiques présentes au site d'infection et dans les ganglions drainants in vivo, après inoculation intra-dermale de L. major dans le pavillon auriculaire de souris de souche C57BL/6 et BALB/c, ainsi que les conséquences de la déplétion des neutrophiles sur l'évolution de la maladie. Nous avons pu démontrer que les neutrophiles ont un impact négatif sur l'activation des cellules dendritiques exposées à L. major in vitro, via des mécanismes impliquant la sécrétion de Prostaglandines par les neutrophiles et la séquestration des parasites. La déplétion des neutrophiles dans les souris BALB/c durant les premiers jours après infection avec L. major dans le derme de l'oreille résulte en une augmentation de l'expression de marqueurs d'activation des cellules dendritiques présentes dans les ganglions drainants, mais pas au site d'infection. De plus, les souris BALB/c transitoirement déplétées en neutrophiles développent des lésions significativement plus petites, une réponse de type Th2 diminuée et une charge parasitaire plus faible au site d'infection que les souris non déplétées. La déplétion des neutrophiles dans les souris C57BL/6 n'a pas d'influence détectable sur l'activation des cellules dendritiques que ce soit au niveau des ganglions drainants ou au site d'infection. La progression de la lésion et la charge parasitaire ne sont pas affectées par la déplétion des neutrophiles, malgré le développement d'une réponse Th2 diminuée par rapport aux souris non déplétées. En résumé, dans les premières heures après infection, les neutrophiles ont un effet négatif sur l'activation des cellules dendritiques et sur la réponse anti-Leishmania dans les souris BALB/c tandis que leur rôle paraît moins important dans les souris C57BL/6. Ces résultats peuvent avoir d'importantes implications en terme de développement de nouveaux vaccins contre Leishmania. - Neutrophils constitute the first line of defense against a variety of pathogens. Following Leihmania major infection neutrophils migrate rapidly and massively to the site of parasite inoculation. They are important players in the orchestration of the anti-leishmania response through the release of a plethora of cytokines, chemokines and granular components. In addition, neutrophils interact with antigen-presenting cells such as dendritic cells (DCs) and thereby contribute to the development of the adaptive immune response. However, the impact of neutrophils on the activation of DCs and possible consequences on disease progression following L. major infection are poorly understood. Therefore, we first investigated the influence of neutrophils on DC activation in vitro. Next we analyzed the role of neutrophils on the activation of DCs present at the site of infection and in the draining lymph node (dLN) following inoculation of L. major in the ear pinna of C57BL/6 and BALB/c mice and analyzed the consequences of early neutrophil depletion on disease progression. We could demonstrate that neutrophils had a negative impact on the activation of DCs exposed to L. major in vitro through mechanisms involving neutrophil-derived prostaglandins and sequestration of parasites. In BALB/c mice, depletion of neutrophils during the first days of infection with L. major in the ear dermis increased the expression of activation markers on dLN DCs but not on DCs present at the site of infection. In addition, BALB/c mice transiently depleted of neutrophils developed significantly smaller lesions, a decreased Th2 immune response and harbored fewer parasites at the site of infection compared to non-depleted littermates. In C57BL/6, mice early depletion of neutrophils had no detectable impact on the activation of DCs both at the site of infection and in the dLN following L. major inoculation. Furthermore, depletion of neutrophils had no major effect on lesion evolution and parasite loads despite the development of a decreased Th2 immune response compared to non- depleted littermates. In summary, at the onset of infection, neutrophils are detrimental for DC activation and the anti-leishmania response in BALB/c mice while their role appears to be less important in C57BL/6 mice. These findings could have important implications for the design of new vaccination strategies.

Disc degeneration: current surgical options.

Chronic low back pain attributed to lumbar disc degeneration poses a serious challenge to physicians. Surgery may be indicated in selected cases following failure of appropriate conservative treatment. For decades, the only surgical option has been spinal fusion, but its results have been inconsistent. Some prospective trials show superiority over usual conservative measures while others fail to demonstrate its advantages. In an effort to improve results of fusion and to decrease the incidence of adjacent segment degeneration, total disc replacement techniques have been introduced and studied extensively. Short-term results have shown superiority over some fusion techniques. Mid-term results however tend to show that this approach yields results equivalent to those of spinal fusion. Nucleus replacement has gained some popularity initially, but evidence on its efficacy is scarce. Dynamic stabilisation, a technique involving less rigid implants than in spinal fusion and performed without the need for bone grafting, represents another surgical option. Evidence again is lacking on its superiority over other surgical strategies and conservative measures. Insertion of interspinous devices posteriorly, aiming at redistributing loads and relieving pain, has been used as an adjunct to disc removal surgery for disc herniation. To date however, there is no clear evidence on their efficacy. Minimally invasive intradiscal thermocoagulation techniques have also been tried, but evidence of their effectiveness is questioned. Surgery using novel biological solutions may be the future of discogenic pain treatment. Collaboration between clinicians and basic scientists in this multidisciplinary field will undoubtedly shape the future of treating symptomatic disc degeneration.

Investigation of Plastic Pipes for Highway Applications, HR-373A, Phase II, 1997

It is generally accepted that high density polyethylene pipe (HDPE) performs well under live loads with shallow cover, provided the backfill is well compacted. Although industry standards require carefully compacted backfill, poor inspection and/or faulty construction may result in soils that provide inadequate restraint at the springlines of the pipes thereby causing failure. The objectives of this study were: 1) to experimentally define a lower limit of compaction under which the pipes perform satisfactorily, 2) to quantify the increase in soil support as compaction effort increases, 3) to evaluate pipe response for loads applied near the ends of the buried pipes, 4) to determine minimum depths of cover for a variety of pipes and soil conditions by analytically expanding the experimental results through the use of the finite element program CANDE. The test procedures used here are conservative especially for low-density fills loaded to high contact stresses. The failures observed in these tests were the combined effect of soil bearing capacity at the soil surface and localized wall bending of the pipes. Under a pavement system, the pipes' performance would be expected to be considerably better. With those caveats, the following conclusions are drawn from this study. Glacial till compacted to 50% and 80% provides insufficient support; pipe failureoccurs at surface contact stresses lower than those induced by highway trucks. On the other hand, sand backfill compacted to more than 110 pcf (17.3 kN/m3) is satisfactory. The failure mode for all pipes with all backfills is localized wall bending. At moderate tire pressures, i.e. contact stresses, deflections are reduced significantly when backfill density is increased from about 50 pcf (7.9 kN/m^3) to 90 pcf (14.1 kN/m^3). Above that unit weight, little improvement in the soil-pipe system is observed. Although pipe stiffness may vary as much as 16%, analyses show that backfill density is more important than pipe stiffness in controlling both deflections at low pipe stresses and at the ultimate capacity of the soil-pipe system. The rate of increase in ultimate strength of the system increases nearly linearly with increasing backfill density. When loads equivalent to moderate tire pressures are applied near the ends of the pipes, pipe deflections are slighly higher than when loaded at the center. Except for low density glacial till, the deflections near the ends are not excessive and the pipes perform satisfactorily. For contact stresses near the upper limit of truck tire pressures and when loaded near the end, pipes fail with localized wall bending. For flowable fill backfill, the ultimate capacity of the pipes is nearly doubled and at the upper limit of highway truck tire pressures, deflections are negligible. All pipe specimens tested at ambient laboratory room temperatures satisfied AASHTO minimum pipe stiffness requirements at 5% deflection. However, nearly all specimens tested at elevated pipe surface temperatures, approximately 122°F (50°C), failed to meet these requirements. Some HDPE pipe installations may not meet AASHTO minimum pipe stiffness requirements when installed in the summer months (i.e. if pipe surface temperatures are allowed to attain temperatures similar to those tested here). Heating of any portion of the pipe circumference reduced the load carrying capacity of specimens. The minimum soil cover depths, determined from the CANOE analysis, are controlled by the 5% deflection criterion. The minimum soil cover height is 12 in. (305 mm). Pipes with the poor silt and clay backfills with less than 85% compaction require a minimum soil cover height of 24 in. (610 mm). For the sand at 80% compaction, the A36 HDPE pipe with the lowest moment of inertia requires a minimum of 24 in. (610 mm) soil cover. The C48 HDPE pipe with the largest moment of inertia and all other pipes require a 12 in. (305 mm) minimum soil cover.

Investigation of High Density Polyethylene Pipe for Highway Applications, HR-373, Phase 1, 1996

In the past, culvert pipes were made only of corrugated metal or reinforced concrete. In recent years, several manufacturers have made pipe of lightweight plastic - for example, high density polyethylene (HDPE) - which is considered to be viscoelastic in its structural behavior. It appears that there are several highway applications in which HDPE pipe would be an economically favorable alternative. However, the newness of plastic pipe requires the evaluation of its performance, integrity, and durability; A review of the Iowa Department of Transportation Standard Specifications for Highway and Bridge Construction reveals limited information on the use of plastic pipe for state projects. The objective of this study was to review and evaluate the use of HDPE pipe in roadway applications. Structural performance, soil-structure interaction, and the sensitivity of the pipe to installation was investigated. Comprehensive computerized literature searches were undertaken to define the state-of-the-art in the design and use of HDPE pipe in highway applications. A questionnaire was developed and sent to all Iowa county engineers to learn of their use of HDPE pipe. Responses indicated that the majority of county engineers were aware of the product but were not confident in its ability to perform as well as conventional materials. Counties currently using HDPE pipe in general only use it in driveway crossings. Originally, we intended to survey states as to their usage of HDPE pipe. However, a few weeks after initiation of the project, it was learned that the Tennessee DOT was in the process of making a similar survey of state DOT's. Results of the Tennessee survey of states have been obtained and included in this report. In an effort to develop more confidence in the pipe's performance parameters, this research included laboratory tests to determine the ring and flexural stiffness of HDPE pipe provided by various manufacturers. Parallel plate tests verified all specimens were in compliance with ASTM specifications. Flexural testing revealed that pipe profile had a significant effect on the longitudinal stiffness and that strength could not be accurately predicted on the basis of diameter alone. Realizing that the soil around a buried HDPE pipe contributes to the pipe stiffness, the research team completed a limited series of tests on buried 3 ft-diameter HDPE pipe. The tests simulated the effects of truck wheel loads above the pipe and were conducted with two feet of cover. These tests indicated that the type and quality of backfill significantly influences the performance of HDPE pipe. The tests revealed that the soil envelope does significantly affect the performance of HDPE pipe in situ, and after a certain point, no additional strength is realized by increasing the quality of the backfill.

Expression and function of macrophage migration inhibitory factor (MIF) in melioidosis.

BACKGROUND: Macrophage migration inhibitory factor (MIF) has emerged as a pivotal mediator of innate immunity and has been shown to be an important effector molecule in severe sepsis. Melioidosis, caused by Burkholderia pseudomallei, is an important cause of community-acquired sepsis in Southeast-Asia. We aimed to characterize the expression and function of MIF in melioidosis. METHODOLOGY AND PRINCIPAL FINDINGS: MIF expression was determined in leukocytes and plasma from 34 melioidosis patients and 32 controls, and in mice infected with B. pseudomallei. MIF function was investigated in experimental murine melioidosis using anti-MIF antibodies and recombinant MIF. Patients demonstrated markedly increased MIF mRNA leukocyte and MIF plasma concentrations. Elevated MIF concentrations were associated with mortality. Mice inoculated intranasally with B. pseudomallei displayed a robust increase in pulmonary and systemic MIF expression. Anti-MIF treated mice showed lower bacterial loads in their lungs upon infection with a low inoculum. Conversely, mice treated with recombinant MIF displayed a modestly impaired clearance of B. pseudomallei. MIF exerted no direct effects on bacterial outgrowth or phagocytosis of B. pseudomallei. CONCLUSIONS: MIF concentrations are markedly elevated during clinical melioidosis and correlate with patients' outcomes. In experimental melioidosis MIF impaired antibacterial defense.

Demonstration Project using Railroad Flatcars for Low-Volume Road Bridges, TR-444, 2003

The use of Railroad Flatcars (RRFCs) as the superstructure on low-volume county bridges has been investigated in a research project conducted by the Bridge Engineering Center at Iowa State University. These bridges enable county engineers to replace old, inadequate county bridge superstructures for less than half the cost and in a shorter construction time than required for a conventional bridge. To illustrate their constructability, adequacy, and economy, two RRFC demonstration bridges were designed, constructed, and tested: one in Buchanan County and the other in Winnebago County. The Buchanan County Bridge was constructed as a single span with 56-ft-long flatcars supported at their ends by new, concrete abutments. The use of concrete in the substructure allowed for an integral abutment at one end of the bridge with an expansion joint at the other end. Reinforced concrete beams (serving as longitudinal connections between the three adjacent flatcars) were installed to distribute live loads among the RRFCs. Guardrails and an asphalt milling driving surface completed the bridge. The Winnebago County Bridge was constructed using 89-ft-long flatcars. Preliminary calculations determined that they were not adequate to span 89 ft as a simple span. Therefore, the flatcars were supported by new, steel-capped piers and abutments at the RRFCs' bolsters and ends, resulting in a 66-ft main span and two 10-ft end spans. Due to the RRFC geometry, the longitudinal connections between adjacent RRFCs were inadequate to support significant loads; therefore, transverse, recycled timber planks were utilized to effectively distribute live loads to all three RRFCs. A gravel driving surface was placed on top of the timber planks, and a guardrail system was installed to complete the bridge. Bridge behavior predicted by grillage models for each bridge was validated by strain and deflection data from field tests; it was found that the engineered RRFC bridges have live load stresses significantly below the AASHTO Bridge Design Specification limits. To assist in future RRFC bridge projects, RRFC selection criteria were established for visual inspection and selection of structurally adequate RRFCs. In addition, design recommendations have been developed to simplify live load distribution calculations for the design of the bridges. Based on the results of this research, it has been determined that through proper RRFC selection, construction, and engineering, RRFC bridges are a viable, economic replacement system for low-volume road bridges.

Design and Performance Verification of UHPC Piles for Deep Foundations, TR-558, 2008

The strategic plan for bridge engineering issued by AASHTO in 2005 identified extending the service life and optimizing structural systems of bridges in the United States as two grand challenges in bridge engineering, with the objective of producing safer bridges that have a minimum service life of 75 years and reduced maintenance cost. Material deterioration was identified as one of the primary challenges to achieving the objective of extended life. In substructural applications (e.g., deep foundations), construction materials such as timber, steel, and concrete are subjected to deterioration due to environmental impacts. Using innovative and new materials for foundation applications makes the AASHTO objective of 75 years service life achievable. Ultra High Performance Concrete (UHPC) with compressive strength of 180 MPa (26,000 psi) and excellent durability has been used in superstructure applications but not in geotechnical and foundation applications. This study explores the use of precast, prestressed UHPC piles in future foundations of bridges and other structures. An H-shaped UHPC section, which is 10-in. (250-mm) deep with weight similar to that of an HP10×57 steel pile, was designed to improve constructability and reduce cost. In this project, instrumented UHPC piles were cast and laboratory and field tests were conducted. Laboratory tests were used to verify the moment-curvature response of UHPC pile section. In the field, two UHPC piles have been successfully driven in glacial till clay soil and load tested under vertical and lateral loads. This report provides a complete set of results for the field investigation conducted on UHPC H-shaped piles. Test results, durability, drivability, and other material advantages over normal concrete and steel indicate that UHPC piles are a viable alternative to achieve the goals of AASHTO strategic plan.

Field Evaluation of Alternative Load Transfer Device Locations in Low Traffic Volume Pavements, TR-420, 2003

In jointed portland cement concrete pavements, dowel bars are typically used to transfer loads between adjacent slabs. A common practice is for designers to place dowel bars at a certain, consistent spacing such that a sufficient number of dowels are available to effectively transfer anticipated loads. In many cases, however, the standards developed today for new highway construction simply do not reflect the design needs of low traffic volume, rural roads. The objective of this research was to evaluate the impact of the number of dowel bars and dowel location on joint performance and ultimately on pavement performance. For this research, test sections were designed, constructed, and tested in actual field service pavement. Test sections were developed to include areas with load transfer assemblies having three and four dowels in the outer wheel path only, areas with no joint reinforcement whatsoever, and full lane dowel basket assemblies as the control. Two adjacent paving projects provided both rural and urban settings and differing base materials. This report documents the approach to implementing the study and provides discussion and suggestions based on the results of the research. The research results indicate that the use of single three or four dowel basket assemblies in the outer wheel path is acceptable for use in low truck volume roads. In the case of roadways with relatively stiff bases such as asphalt treated or stabilized bases, the use of the three dowel bar pattern in the outside wheel path is expected to provide adequate performance over the design life of the pavement. In the case of untreated or granular bases, the results indicate that the use of the three or four dowel bar basket in both wheel paths provides the best long-term solution to load transfer and faulting measurements.

Feasibility Investigation of Segmentally Precast Bridge Piers for Accelerated Construction, TR-556, 2009

An innovative structural system for pier columns was investigated through a series of laboratory experiments. The columns and connections examined were comprised of precast concrete segments to accelerate construction. In addition some of the columns employed unbonded post-tensioning to self-center the columns when subjected to lateral loads and structural fuses to control large lateral deflections, dissipate energy, and expedite repair in the event of a catastrophic loading event. Six cantilever columns with varying component materials and connection details were subjected to a regimen of vertical dead loads and cyclic, quasi-static lateral loads. One column was designed as a control column to represent the behavior of a conventional reinforced concrete column and provide a basis for comparison with the remaining five jointed columns designed with the proposed structural system. After sustaining significant damage, the self-centering, jointed columns were repaired by replacing the structural fuses and retested to failure to investigate the effectiveness of the repair. The experiments identified both effective and unsatisfactory details for the jointed system. Two of the jointed columns demonstrated equivalent lateral strength, greater lateral stiffness, and greater lateral deformation capacity than the control column. The self-centering capability of the jointed columns was clearly demonstrated as well, and the repair technique proved effective as demonstrated by nearly identical pre and post repair behavior. The authors believe the proposed system to be a feasible alternative to conventional pier systems and recommend further development of details.

Field Instrumentation, Testing, and Long-Term Monitoring of High-Mast Lighting Tower No. 1 at the I-35/US 18 Interchange Near Clear Lake in the State of Iowa Phase 3, TR-562, 2009

The current study was initiated to quantify the stresses induced in critical details on the reinforcing jacket and the tower itself through the use of field instrumentation, load testing, and long-term monitoring. Strain gages were installed on the both the tower and the reinforcing jacket. Additional strain gages were installed on two anchor rods. Tests were conducted with and without the reinforcing jacket installed. Data were collected from all strain gages during static load testing and were used to study the stress distribution of the tower caused by known loads, both with and without the reinforcing jacket. The tower was tested dynamically by first applying a static load, and then quickly releasing the load causing the tower to vibrate freely. Furthermore, the tower was monitored over a period of over 1 year to obtain stress range histograms at the critical details to be used for a fatigue evaluation. Also during the long-term monitoring, triggered time-history data were recorded to study the wind loading phenomena that excite the tower.