Bay Bridge Research Articles

Electric Aircraft and the Environment: A Literature Review

Historically, the integration of social need, environmental impact, and technological advancement has been a challenging balancing act for growing cities and metropoles. If the balance between social need and environmental sustainability is reached, the increasing advancements and improvements made to electric aircrafts have the potential to steer society towards a new mode of sustainable air. One reason why electric aircraft technology has not grown as fast as other technologies is because there lacked a need for fast advancements. With that said, electric aircraft technologies are improving today due to the demand in heavily populated cities to relieve traffic [5]. Some issues growing cities face are inadequate housing, inefficient infrastructure, and high traffic congestion. According to the Metropolitan Transportation Commission (MTC), traffic congestion within the Bay Area has increased 9% in the past two years [5]. The gridlock in the Bay Area increased as approximately 13,000 cars cross the Bay Bridge daily. A report produced by Arup Corporation reports that the Bay Area is second only to Los Angeles in the intensity of traffic congestion [1]. A study by UCLA determined that the economic boom in the Bay Area in the previous decade had driven the influx of inhabitants to the area [5]. These are two examples of metropolitan cities that are impacted by traffic congestion. To mitigate the negative consequences associated with high traffic congestion, it is beneficial to explore redesigning the infrastructure of metropolitan cities in tandem with residual effects of the economic boom. [5]. This literature review analyzes electric aircraft as a viable solution to high congestion and explores the possible effects of it on the environment.

Combination of Power Function and Log-Linear Models to Estimate Pile Setup

This paper presents a new approach of estimating pile setup starts from the end-of-drive (EOD) resistance by the use of a power function model followed by a log-linear function. Often pile setup is estimated using the Skov and Denver(in: Proceedings of the 3rd international conference on the application of stress-wave theory to piles, Canada, 1988) model, which requires knowing the pile resistance at a reference time (to). This requires additional effort for testing the pile at the reference time (to). This effort may cause delay in the foundation construction and thus increasing the cost of construction. Pile load testing program was conducted on seven 914 (36 in.) square close-ended prestressed concrete (PSC) test piles at the Caminada Bay bridge project in coastal Louisiana to develop a methodology to estimate pile setup effectively starting from EOD resistance. Several dynamic load tests (DLTs) were performed on each test pile, with waiting periods of 60 min to 55 days after installation, to measure the magnitude and rate of setup. Static load tests (SLTs) were also performed at the end of the load testing program to validate the results of dynamic load tests. The load testing results showed that the total resistance increased up to 12 times of the EOD resistances after 28 days from EOD. The Skov and Denver (1988) setup parameter “A” was calculated for each test pile using different initial reference times (to). The results showed that the setup parameter “A” was highly variable and uncertain for to less than 1 day. This paper proposes a new power pile setup model that can be used to estimate pile setup immediately after EOD to the initial reference time, to, which is usually 1 day for a log-linear model. The proposed model was validated using results from published case studies for various geological conditions, which shows that the results of the model effectively match the setup test results within a small tolerance.

Expert Level Control of Ramp Metering Based on Multi-Task Deep Reinforcement Learning

This paper shows how the recent breakthroughs in reinforcement learning (RL) that have enabled robots to learn to play arcade video games, walk, or assemble colored bricks, can be used to perform other tasks that are currently at the core of engineering cyberphysical systems. We present the first use of RL for the control of systems modeled by discretized non-linear partial differential equations (PDEs) and devise a novel algorithm to use non-parametric control techniques for large multi-agent systems. Cyberphysical systems (e.g., hydraulic channels, transportation systems, the energy grid, and electromagnetic systems) are commonly modeled by PDEs, which historically have been a reliable way to enable engineering applications in these domains. However, it is known that the control of these PDE models is notoriously difficult. We show how neural network-based RL enables the control of discretized PDEs whose parameters are unknown, random, and time-varying. We introduce an algorithm of mutual weight regularization (MWR), which alleviates the curse of dimensionality of multi-agent control schemes by sharing experience between agents while giving each agent the opportunity to specialize its action policy so as to tailor it to the local parameters of the part of the system it is located in. A discretized PDE, such as the scalar Lighthill–Whitham–Richards PDE can indeed be considered as a macroscopic freeway traffic simulator and which presents the most salient challenges for learning to control large cyberphysical system with multiple agents. We consider two different discretization procedures and show the opportunities offered by applying deep reinforcement for continuous control on both. Using a neural RL PDE controller on a traffic flow simulation based on a Godunov discretization of the San Francisco Bay Bridge, we are able to achieve precise adaptive metering without model calibration thereby beating the state of the art in traffic metering. Furthermore, with the more accurate BeATS simulator, we manage to achieve a control performance on par with ALINEA, a state-of-the-art parametric control scheme, and show how using MWR improves the learning procedure.

Transpacific Cyberpunk: Transgeneric Interactions between Prose, Cinema, and Manga

This paper attempts to meditate upon the transpacific imagination of cyberpunk by reconstructing its literary and cultural heritage. Since the publication of William Gibson’s multiple award winning first novel, Neuromancer (1984), the concept of cyberpunk has been globally popularized and disseminated not only in the field of literature but also in culture. However, we should not forget that cyberpunk is derived not only from the cutting edge of technology but also from “Lo Tek” sensibility cultivated in the Gibsonian picturesque ruins or dark cities such as a major extraterritorial zone in Hong Kong “Kowloon Walled City” nicknamed as “a den of iniquity”, “The Casba of the East”, and “a hotbed of crime”, which was destroyed in 1993, but whose images captured by Ryuji Miyamoto inspired Gibson to come up with the spectacle of the destroyed San Francisco Bay Bridge to be stormed by ex-hippies and former homeless. From this perspective, this chapter focuses on the works ranging from Katsuhiro Otomo’s directed anime Akira (1988), Gibson’s Bridge Trilogy (Virtual Light (1993), Idoru (1996), and All Tomorrow’s Parties (1998)) in the 1990s through Project Itoh’s post-cyberpunk masterpiece Genocidal Organ (2007).

Impacts of human activity and extreme weather events on sedimentary organic matter in the Andong salt marsh, Hangzhou Bay, China

In this study, lignin-derived phenols, stable carbon isotopes and bulk elemental compositions were determined along the length of two sediment cores (C1 and C2) from the Andong salt marsh, which is located southwest of Hangzhou Bay, China. The purpose of this study was to determine the short-term changes and their implications along sediment profiles. The 1997 high tide had caused an increase in the terrestrial organic matter (OM) signal from 1996/1997 to 2000 in both cores, which was indicated by a high Λ (total lignin in mg/100mg OC), TOC, C/N and more negative δ13C values. The slight increases in terrestrial OM along the length of the cores between 2003 and 2006 were most likely attributable to the construction of the Hangzhou Bay Bridge. Both events have likely caused an increase in erosion, and thus, these events have increased the input of terrestrial OM to nearby areas. The effects of the distinctively dry year of 2006 can be observed along C2 between 2006 and 2008 in the steadily declining terrestrial OM signal. The overall slight decrease in terrestrial OM and the distinct increase in TOC along the length of both cores toward the present were most likely because of the overall reduced sediment caused by the trapping of materials within reservoirs. These results show that the reduction in terrestrial OM in the Andong salt marsh for the past 30 years was due to reservoirs and the 2006 drought, but this was counterbalanced by the 1997 high tide event and construction of the Hangzhou Bay Bridge, which resulted in increased erosion and terrestrial OM input.

Pensacola Bay Bridge Crown Jewel of Northwest Florida

Pensacola Bay Bridge Crown Jewel of Northwest Florida

Nonlinear cumulative damage model and application to bridge fatigue life evaluation

Fatigue is a damage accumulation process in which material property deteriorates continuously. Fatigue life prediction issues are important for safety. This article aims to develop a nonlinear cumulative damage model. A fatigue damage model based on the continuum damage mechanics is addressed and applied to bridge fatigue life evaluation. First, the bridge nonlinear cumulative damage model based on damage mechanics is propounded and equivalent effective stress range is given. Then, the effects of the main parameter in the model are analyzed. Finally, Xinghai Bay Bridge is taken as a case study. The results indicate that the damage is increased with the material parameter [Formula: see text] reduced. [Formula: see text] is a material parameter depending on stress amplitude and without physical meaning. If [Formula: see text], the effect of [Formula: see text] is negligible. If [Formula: see text], nonlinear cumulative damage model degrades into Miner’s rule and effect of [Formula: see text] to structural damage is maximum. The cumulative damage curve calculated by the nonlinear cumulative damage model is nonlinear, with a low cumulative rate initially but a very high cumulative rate at the end of the design life, whereas the Miner’s rule is linear. The nonlinear cumulative damage model can reflect actual damage process, while Miner’s rule is pessimistic.

Review: A Tale of Two Bridges: The San Francisco Oakland Bay Bridges of 1936 and 2013 by Stephen D. Mikesell

Book Review| November 01 2017 Review: A Tale of Two Bridges: The San Francisco Oakland Bay Bridges of 1936 and 2013 by Stephen D. Mikesell A Tale of Two Bridges: The San Francisco Oakland Bay Bridges of 1936 and 2013. By Stephen D. Mikesell (Reno: University of Nevada Press, 2017. 208 pp. $31.96 paperback). Ira B. Nadel Ira B. Nadel Ira B. Nadel is a Professor of English at the University of British Columbia, a Fellow of the Royal Society of Canada, and winner of the 1996 Medal for Canadian Biography. His book with David MacDonald, Golden Gate Bridge, History and Design of an Icon (2008) is an interesting departure from his usual focus upon biography, Victorians, and select Modernists. Search for other works by this author on: This Site PubMed Google Scholar Southern California Quarterly (2017) 99 (4): 483–486. https://doi.org/10.1525/scq.2017.99.4.483 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Cite Icon Cite Search Site Citation Ira B. Nadel; Review: A Tale of Two Bridges: The San Francisco Oakland Bay Bridges of 1936 and 2013 by Stephen D. Mikesell. Southern California Quarterly 1 November 2017; 99 (4): 483–486. doi: https://doi.org/10.1525/scq.2017.99.4.483 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentSouthern California Quarterly Search This content is only available via PDF. © 2017 by The Historical Society of Southern California2017 Article PDF first page preview Close Modal You do not currently have access to this content.

Review: A Tale of Two Bridges: The San Francisco–Oakland Bay Bridges of 1936 and 2013 by Stephen D. Mikesell

Review: A Tale of Two Bridges: The San Francisco–Oakland Bay Bridges of 1936 and 2013 by Stephen D. Mikesell

Scour Depth Determination of Bridge Piers Based on Time-Varying Modal Parameters: Application to Hangzhou Bay Bridge

Scour Depth Determination of Bridge Piers Based on Time-Varying Modal Parameters: Application to Hangzhou Bay Bridge

Structural health monitoring system of the long-span bridges in Turkey

This study presents the general features of the structural health monitoring (SHM) system of the long-span cable-supported bridges in Turkey, namely the First Bosphorus Bridge, the Second Bosphorus Bridge (Fatih Sultan Mehmet Bridge), the newly constructed the Third Bosphorus Bridge (Yavuz Sultan Selim) and the Osman Gazi Bridge (Izmit Bay Bridge). Due to the critical function of the bridges in the transportation networks of Istanbul, structural health under extreme and operational load cases without interruption of their operation is essential. The SHM systems are already available and in use for the First and Second Bosphorus Bridges; however, the Yavuz Sultan Selim and the Osman Gazi Bridges, only have the preliminary SHM systems established. General preferences of the current and planned SHM systems of the bridges are given based on the monitoring objectives and requirements. Data collected from the SHM systems are also exhibited as an illustration for structural modal identification of the First Bosphorus Bridge. Based on the experiences from the current SHM systems, future works and planning are recommended to effectively design new SHM system and to efficiently update the current ones.

Challenges of civil engineering megaprojects in North America

In many respects, megaprojects define the civil engineering profession, going back to the Panama Canal and the Hoover dam. They present many challenges. By definition, they are large, innovative projects that have never been done before. The Boston Central Artery/Tunnel and the San Francisco–Oakland Bay Bridge are now in service and by all accounts are performing well. However, these both had large cost overruns and concerns about quality and lengthy construction delays. The Central Artery/Tunnel also suffered a fatal ceiling collapse. Megaprojects require careful management. Owners and builders must be transparent and responsive to open record requests. Public employees should be empowered to bring forward concerns about quality and safety issues. The agencies should establish reliable open channels of communication with the public. Cost estimates should consider risk and provide for both best and worst cases. Independent inspection agencies should be established to provide oversight of large projects.

Tidal stream energy resource assessment in the Qiantang River Estuary, China

ABSTRACTA tidal stream energy resource assessment can be achieved through direct measurements of tidal elevations or flow velocities, theoretical formulas, and numerical models. This paper first described the development of renewable energy in China. Then, the tidal stream energy resource in the Qiantang River Estuary was assessed. The present work established a 2D numerical model for calculating the power density in the estuary and validated it with in situ water level, tidal current, and suspended sediment concentration measurements. Three possible sites found near the Hangzhou Bay Bridge were selected for detailed resource assessment. The results indicated that if only 50 turbines are deployed to each site, the tidal stream energy output by all turbines would be 7.5 GWh/year. Finally, building a tidal stream power generation device into an existing bridge structure was proposed at the Qiantang River Estuary.

Environmental Hydrogen Embrittlement of G41400 and G43400 Steel Bolting in Atmospheric Versus Immersion Services

This article is based on a review of data in the literature and those released by the California Department of Transportation and reported by the Bureau of Safety and Environmental Enforcement (BSEE). In 2013, hot dip galvanized (HDG) threaded rods failed due to environmental hydrogen embrittlement (EHE) cracking on the San Francisco–Oakland Bay Bridge. These rods were made of G41400 steel, conforming to ASTM A354 Grade BD (39 HRC max). All 32 EHE failures occurred in the bottom threads that had been immersed in pools of water, inadvertently, under no stress, for over four years before they were pretensioned. Several failure analysis reports stated that they failed due to EHE cracking because they were pretensioned while being immersed in water. This is erroneous, however, because one or more of the failed rods were not immersed in water during pretensioning and afterward. Conversely, hydrogen from metal corrosion of the HDG BD rods can diffuse into them under no stress while corroding in standing water for several years. The EHE cracking occurred when subsequently pretensioned. None of about 4000 threaded ends of HDG BD rods that have been exposed only to marine atmosphere (but not immersed in water) has failed in three to four years in service under a pretension load. These data are compared with recent EHE cracking of G43400 bolting in subsea oil production facilities in the Gulf of Mexico, reported by the BSEE.

Ecological risk and contamination history of heavy metals in the Andong tidal flat, Hangzhou Bay, China

ABSTRACTIn this study, we collected two sediment cores (C1 and C2) from the Andong tidal flat, Hangzhou Bay, and studied the temporal variations of heavy metals in the cores. Vertical distributions of heavy metals were almost unchanged in both the cores before 2000. After 2000, however, the heavy metal concentrations increased dramatically, suggesting that the sediments have been affected by enhanced human pollution in the recent decade. In the core C1, the sediments were severely polluted by Pb, moderately to considerably polluted by Cr and Zn, and low to moderately polluted by other heavy metals. The core C2 was relatively unpolluted before 2000 and low to moderately polluted after 2000. Multi-statistical analyses indicated that the core C1 was additionally contaminated by local human activities such as wastewater discharge and the Hangzhou Bay Bridge. The heavy metals in the core C2, however, were largely contributed by the Yangtze River and controlled by sedimentation process. The calculated sedimentary flux (4–8 g m−2 a−1) of heavy metals generally increased with time. It was closely related to the wastewater discharge in adjacent areas. This study reconstructed the local heavy metal pollution history and provides important information for environmental protection and policy making.

Earthquake Resilience of Reinforced Concrete Structural Walls with Replaceable “Fuses”

ABSTRACTThe concept of providing a fuse in a structural system has been both developed and investigated over the past few years (e.g., the use of replaceable links in eccentrically braced frames or the use of replaceable links in the new San Francisco-Oakland Bay Bridge). This paper presents a new coupling beam with a creative fuse installed in the mid-span of a steel-concrete composite beam via an end plate and high-strength bolts. First, a practical design methodology of a replaceable coupling beam is presented. Next, the seismic behavior of the proposed fuse is tested and evaluated, and two structural wall specimens with or without a fuse are designed and fabricated according to the proposed design methods. The two specimens possess similar shear capacities under large-scale cyclic loading, and the walls of the two specimens show similar failure modes; however, the new walls exhibit slightly lower levels of damage than the conventional walls. In particular, the inelastic deformation and damage of replaceable coupling beams are mainly concentrated in the fuse, whereas the non-yield segment and the beam-wall pier interfaces remain nearly intact and produce only slight damage, which is beneficial regarding the replacement of the fuse in post-earthquake events.

Stewardship in Large Public Projects: The Practicality of Shakespeare

Can reading great literature, considering its heroes and small characters, improve the performance of public sector actors? King Lear’s characters fault a wickedly disinterested heaven for life’s setbacks and woes. Yet Shakespeare makes clear that these actors’ own terrible choices beset the king, his family and the rest of us who are subject to the acts of public leaders. Reading this literature as analogy for the effectiveness of the modern public sector suggests how administrative operation of our democratic state may – or may not – successfully parcel power and control so as to limit negative externalities derived from ill-informed, self-serving or rent-seeking executive and individual decisions. Lear’s tragic arc mimics a sorrowful “muddling through” and potentially unnecessary “satisficing” in certain large public works projects. One large public project currently deemed successful is examined here – the replacement of the eastern span of the Bay Bridge in San Francisco – as a reflection on separated powers, the limits of human nature, and the inevitability of error.

Prediction and Monitoring of Underwater Sound Levels from the Implosion of a Reinforced Concrete Bridge Pier

After the completion of the new east span of the San Francisco–Oakland Bay Bridge in California, large concrete piers of the old span needed to be demolished. To consider using controlled blasting for this action, hydroacoustic levels were predicted and monitored with regard to specified fish and marine mammal criteria. The metrics included peak pressure and sound exposure levels at distances from 25 to more than 4,000 ft from the pier. For peak pressure, the measured levels were slightly higher than estimated, although for sound exposure levels, the measured levels were somewhat lower than estimated because of the effect of surface reflection. A blast attenuation system consisting of a wide bubble stream was used to minimize the hydroacoustic levels in the water surrounding the pier. The implosion event consisted of 588 individual charge detonations ranging from 35 to 21 lb (15.9 to 9.5 kg/delay) spaced 9 ms apart. Although there were 135 individual detonations of the larger 35-lb charges, the highest peak pressures varied in level by 10 to 15 dB during the course of the implosion. The methods for predicting the levels, measured results, analysis of data, and performance of the blast attenuation system are reviewed.

Numerical Assessment of the Wave Loads on Coastal Twin Bridge Decks under Stokes Waves

ABSTRACT Xu, G.; Cai, C.S.; Han, Y.; Wu, C., and Xue, F., 2018. Numerical assessment of the wave loads on coastal twin bridge decks under Stokes waves. In recent hurricane seasons, many coastal low-lying bridges along the Gulf of the Mexico in the United States have suffered huge damages, which has motivated many studies on the failure mechanisms of these coastal infrastructures. While in previous studies one single bridge deck is usually the focal structure type; this study, instead, addresses the features of the wave loads on coastal low-lying bridges with twin decks that are subject to Stokes waves, identifies the wave reflection effects in the twin bridge deck–wave interaction, and brings forward more questions for future studies on this topic. Based on the geometric parameters of the damaged Escambia Bay Bridge, the wave loads on single and twin bridge decks, considering different still water depths with various structure elevations, are compared first. The observed difference in the comparisons of t...

Crossing the bridge: The effects of time-varying tolls on curbing congestion

This paper estimates the traffic volume and travel time effects of the road congestion pricing implemented on the San Francisco-Oakland Bay Bridge. I employ both difference-in-differences and regression discontinuity approaches to analyze previously unexploited data for the two years spanning the price change and obtain causal estimates of the hourly average treatment effects of the policy. I find evidence of peak spreading in traffic volume and decreases in travel time during peak hours. I also find suggestive evidence of substitution to a nearby bridge and decreases in travel time variability. In addition, I calculate own- and cross-price elasticities.