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Multispan bridges with simply supported girders are straightforward to construct and economical but have historically utilized expansion joints between spans. The negative long-term impacts of expansion joints are well-documented in the literature; eventual leaking causes damage to the girder ends and substructures. To avoid this deterioration associated with the use of expansion joints, link slabs may be used instead. However, the complex induced forces and deformations associated with link slabs are not fully understood and may damage the slab, reducing the life of the superstructure. This paper presents the results of a field study examining bonded link slab behavior under ambient (in-service) live and thermal loads on five Texas bridges. Typical Texas link slabs are not debonded at the girder ends, feature continuous longitudinal reinforcement, and incorporate partial-depth precast concrete panels. The five bridges were instrumented with displacement gauges at the girder ends, at both link slab and expansion joint locations, and strain gauges attached to the bottom of the bridge deck. Displacement, strain, and temperature data collected for a period of 1–2 weeks were used to estimate link slab mechanics. The results show differences in behavior between the differing link slab details, lateral deck stiffness characteristics, and continuous deck unit lengths. The increase in superstructure stiffness provided by the link slab is quantified. Longitudinal deck cracking and reinforcing steel yield behavior are predicted at each monitored link slab. The calculated displacement and strain data show that both live and thermal load effects should be considered in the design. [ABSTRACT FROM AUTHOR]

A sewer system is a principal element of infrastructure in modern cities, accounting for massive amounts of public investments. Corrosion of manholes in the sewer system is a global issue, and millions of dollars are being spent on the maintenance, restoration, and replacement of deteriorated sewer networks. Concrete manholes in the sewer system are deteriorating due to the attack of sulfuric acid produced by microorganisms in a process termed microbial induced concrete corrosion (MICC), which reduces the lifespan of concrete sewer elements. The objective of this paper is to investigate the correlation between the gas- and liquid-phase sewer environmental factors and hydrogen sulfide concentration in the gas phase. The production, emission, and build-up of hydrogen sulfide gas in manholes is identified as a major cause of MICC in manhole shafts. The field study was conducted in more than 200 manholes in the City of Arlington (Texas, US). The data was collected every minute for 48 h to understand the trends of liquid- and gas-phase parameters such as hydrogen sulfide (H2S concentration), liquid and gas temperature, pH, DO, and relative humidity. The study also examines how gas-phase H2S concentrations vary with season; manhole design, including manholes' depth, slope, and presence of drop; and sewer flow conditions such as velocity and turbulence. Although no strong linear correlation was found between liquid-/gas-phase parameters, the manhole categories were found to play a significant role in H2S generation. The manholes with hydraulic jump generated the highest average H2S concentrations, followed by manholes with drops. High turbulence zones were observed in manholes of both categories, leading to H2S stripping from liquid to gas phase. The highest H2S concentration was recorded in summer, suggesting that higher liquid temperature resulted in increased bacterial activity, which generated greater liquid-phase sulfide. Greater Henry's law constants in summer, due to high temperatures, would have favored transfer of liquid-phase sulfide to the gas phase. [ABSTRACT FROM AUTHOR]

The focus of this study is the 1938 Rio Grande Compact water supply. The compact is an interstate agreement signed in 1938 between the states of Colorado, New Mexico, and Texas to evenly apportion the waters of the Rio Grande Basin. A shortage in deliveries is at the center of a lawsuit that began in 2011, went to the Supreme Court in 2013, and has not been resolved. This research statistically characterized the differences between water available and water delivered by Colorado and New Mexico, signatories of the Rio Grande Compact with Texas, to understand changes over time and uncover potential autocorrelations. Unexpected changes in water deliveries can have serious financial impacts on communities, thus the importance of shedding light into the behavior of the differences between water available and delivered. One of the findings of the research was that the annual credit/debit time series for Colorado was significantly correlated with the current and immediately previous scheduled delivery as well as with itself in the two previous years, and the behavior is explained by a transfer function model (TFM). For New Mexico, the annual credit/debit series did not display a clear pattern; therefore, it was not possible to characterize its relationship with scheduled delivery with the method examined. This technical note contributes to the extensive body of literature of the Rio Grande Compact in a way no other study has done as well as contributing to the wealth of literature related to the use of the transfer function model in hydrology. The main contribution of the study is the methodology developed and used, which could be useful to other river systems and transboundary water sharing agreements. This research statistically characterized the differences between water available and water delivered, also known as credits and debits, by Colorado and New Mexico, signatories of the Rio Grande Compact with Texas, to understand changes over time and uncover potential autocorrelations. A legal conflict between the signatories of the compact has lasted over a decade. Texas alleges that New Mexico is extracting groundwater, shortening their share of the water. Unexpected changes in water deliveries can have serious financial impacts on communities so shedding light on the differences between water available and water delivered can contribute to the debate. One of the research findings was that the annual credit/debit time series for Colorado was significantly correlated with the current and immediately previous scheduled delivery as well as with itself in the two previous years, and the behavior is explained by a TFM. For New Mexico, the annual credit/debit series did not display a clear pattern; therefore, it was not possible to characterize its relationship with scheduled delivery with the method examined. The main contribution of the study is the methodology developed and used, specifically the TFM, which could be tweaked to fit other river systems and transboundary water sharing agreements. [ABSTRACT FROM AUTHOR]