Seismic Retrofit of 1958 Carquinez Bridge

1998 ◽  
Vol 1624 (1) ◽  
pp. 54-63 ◽  
Author(s):  
John Hinman ◽  
Vong Toan ◽  
Steve Thoman
Keyword(s):  
San Francisco ◽  
Local Buckling ◽  
High Strength ◽  
The United States ◽  
Steel Members ◽  
Formidable Challenge ◽  
Load Carrying ◽  
Truss Bridge ◽  
Mean Return Period ◽  
Retrofit Design

The 1021-m (3,350-ft) long steel through truss bridge carrying the east-bound lanes of Interstate 80 across the western end of the Carquinez Strait about 40 km (25 mi) north of San Francisco opened to traffic in 1958. It was the first major highway bridge in the United States to use high-strength (T1) steel, the first to use welded built-up members, and the first to use high-strength bolted connections. These “firsts,” combined with the size of the bridge and the traffic demands, presented a formidable challenge to the retrofit design team. The retrofit objective was to prevent collapse of the bridge during an earthquake with an expected mean return period in the range of 1,000 to 2,000 years. Under this noncollapse criterion, significant damage to the bridge, such as yielding and buckling of members, was considered acceptable. It was important, then, that a measure of acceptable damage be defined and that the postyield behavior of the structure be both very predictable and very ductile. A preliminary design was prepared based on an elastic analysis with geometric non-linearities. The retrofit design was then examined by incorporating material nonlinearities into the model; adjustments to the retrofit design were required in some isolated areas. Design issues that the team addressed included connections for loads as high as 60 to 50 kN (13,500 kips); local buckling of thin-walled, high-strength members; postyield behavior of major load-carrying steel members; rocking of rigid A-frame tower assemblies; and an expansion joint for an 8-ft movement rating.

scholarly journals Cold Formed Steel Channel Sections with Flange Stiffeners

2019 ◽  
Vol 9 (1) ◽  
pp. 2458-2463
Keyword(s):  
Ultimate Load ◽  
Weight Ratio ◽  
High Strength ◽  
Thickness Ratio ◽  
Load Carrying Capacity ◽  
Simply Supported ◽  
Steel Members ◽  
Load Carrying ◽  
Cold Formed Steel ◽  
Formed Channel

In recent years the utilization of cold formed steel has been redoubled. This is because high strength to weight ratio of the cold formed steel. The thicknesses cold formed steel members usually range from 0.3 mm to 6.35 mm. The most used cold formed sections are C and Z sections. These sections can be used as secondary beams (purlins) for roof covering, side girts, decks, and panels. Scope of this present study is to investigate the effect on load carrying capacity of cold formed channel sections provided with flange stiffeners. In this project, eighteen numbers of channel sections were analysed by keeping the height to thickness ratio (h/t) as constant and by varying flange width to thickness ratio (b/t) using Ansys 14.0. The h/t ratio and b/t ratio considered are 50 and 25, 35, 45 respectively. The thickness and span of all specimens were kept as 2 mm and 1500 mm respectively. Simply supported boundary condition and two points loading was adopted for both the numerical and experimental analysis. Three numbers of channel sections were fabricated and tested experimentally to check the consistency of results with numerical analysis. The ultimate load and deformed shape of three specimens were obtained from experimental results are compared with the analytical results acquired from Ansys 14.0

Finite Element Analysis on the Local Buckling Behavior of High Strength Steel Members under Axial Compression

2011 ◽  
Vol 243-249 ◽  
pp. 1477-1482 ◽  
Author(s):  
Gang Shi ◽  
Cuo Cuo Lin ◽  
Yuan Qing Wang ◽  
Yong Jiu Shi ◽  
Zhao Liu
Keyword(s):  
Finite Element ◽  
Axial Compression ◽  
High Strength Steel ◽  
Local Buckling ◽  
High Strength ◽  
Finite Element Models ◽  
Loading Capacity ◽  
Element Analysis ◽  
Steel Members ◽  
Buckling Behavior

Compared to the ordinary strength steel extensively applied in structures currently, high strength steel, a new kind of construction material, has many differences on mechanical properties. Though high strength steel has been applied in several projects in the world, which has obtained good effects, there is a lack of the design method for high strength steel structures and researches on the loading capacity of high strength steel members. To study the local buckling behavior of high strength steel members under axial compression, finite element models are developed to predict the loading capacity of high strength steel welded I-section and box-section stub columns under axial compression in this paper. With accurate simulation of 17 high strength steel specimens, the finite element analysis results agree well with the corresponding test results, and the average deviation of the ultimate loading capacity of 17 specimens is about -3.1%. It’s verified that the finite element models developed in this paper can accurately simulate high strength steel members with the initial geometric imperfections and residual stresses, and analyze the local buckling behavior of high strength steel members under axial compression. In addition, it provides a basis for the parametric study of high strength steel members under axial compression in future.

scholarly journals Mechanical Behavior and Failure Mode of Steel–Concrete Connection Joints in a Hybrid Truss Bridge: Experimental Investigation

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2549
Author(s):  
Yingliang Tan ◽  
Bing Zhu ◽  
Le Qi ◽  
Tingyi Yan ◽  
Tong Wan ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Failure Mode ◽  
Failure Modes ◽  
Local Buckling ◽  
High Strength ◽  
Testing Procedure ◽  
Gusset Plates ◽  
Truss Bridges ◽  
Study Results ◽  
Truss Bridge

The core part of a hybrid truss bridge is the connection joint which combines the concrete chord and steel truss-web members. To study the mechanical behavior and failure mode of steel–concrete connection joints in a hybrid truss bridge, static model tests were carried out on two connection joints with the scale of 1:3 under the horizontal load which was provided by a loading jack mounted on the vertical reaction wall. The specimen design, experimental setup and testing procedure were introduced. In the experiment, the displacement, strain level, concrete crack and experimental phenomena were factually recorded. Compared with the previous study results, the experimental results in this study demonstrated that the connection joints had the excellent bearing capacity and deformability. The minimum ultimate load and displacement of the two connection joints were 5200 kN and 59.01 mm, respectively. Moreover, the connection joints exhibited multiple failure modes, including the fracture of gusset plates, the slippage of high-strength bolts, the local buckling of compressive splice plates, the fracture of tensile splice plates and concrete cracking. Additionally, the strain distribution of the steel–concrete connection joints followed certain rules. It is expected that the findings from this paper may provide a reference for the design and construction of steel–concrete connection joints in hybrid truss bridges.

Axial Behavior of Corroded H-Piles

2019 ◽  
Author(s):  
Amro Ramadan ◽  
Mohamed ElGawady
Keyword(s):  
Local Buckling ◽  
Element Model ◽  
The United States ◽  
Wetting And Drying ◽  
Axial Capacity ◽  
Modes Of Failure ◽  
Buckling Behavior ◽  
Load Carrying ◽  
Steel Piles ◽  
Axial Behavior

<p>H-steel piles are commonly used in river-crossing bridges in the United States. Many of these piles suffered from different degrees of corrosion due to repeated cycles of wetting and drying. Corrosion of H-steel piles affects the buckling behavior of piles which affect the axial load carrying capacity of these piles leading to a significant effect on the whole performance of a bridge. This paper presents the findings of an experimental study that was conducted to evaluate the axial behavior of four full-scale H-piles including a reference pile and three corroded piles with different degrees of simulated corrosion. The results indicate that the reduction of the section change the modes of failure from global to local buckling according to the percentage and place of the corrosion. A non-linear finite element model has been validated with the experimental results. Different design approaches were also used to determine the axial capacity of the corroded piles.</p>

Craft Beer's Unlikely Alchemist

2019 ◽  
Vol 19 (4) ◽  
pp. 78-90
Author(s):  
Theresa McCulla
Keyword(s):  
San Francisco ◽  
Assembly Line ◽  
The United States ◽  
Risk Tolerance ◽  
Small Scale ◽  
Intellectual Curiosity ◽  
Brewing Industry ◽  
Washing Machine ◽  
Craft Beer ◽  
History Of

In 1965, Frederick (Fritz) Maytag III began a decades-long revitalization of Anchor Brewing Company in San Francisco, California. This was an unexpected venture from an unlikely brewer; for generations, Maytag's family had run the Maytag Washing Machine Company in Iowa and he had no training in brewing. Yet Maytag's career at Anchor initiated a phenomenal wave of growth in the American brewing industry that came to be known as the microbrewing—now “craft beer”—revolution. To understand Maytag's path, this article draws on original oral histories and artifacts that Maytag donated to the Smithsonian Institution's National Museum of American History via the American Brewing History Initiative, a project to document the history of brewing in the United States. The objects and reflections that Maytag shared with the museum revealed a surprising link between the birth of microbrewing and the strategies and culture of mass manufacturing. Even if the hallmarks of microbrewing—a small-scale, artisan approach to making beer—began as a backlash against the mass-produced system of large breweries, they relied on Maytag's early, intimate connections to the assembly-line world of the Maytag Company and the alchemy of intellectual curiosity, socioeconomic privilege, and risk tolerance with which his history equipped him.

The “Japanese Turn” in Fine Dining in the United States, 1980–2020

2020 ◽  
Vol 20 (2) ◽  
pp. 45-54
Author(s):  
Samuel H. Yamashita
Keyword(s):  
United States ◽  
New York ◽  
Los Angeles ◽  
San Francisco ◽  
San Francisco Bay Area ◽  
The United States ◽  
First Century ◽  
Further Training ◽  
Bay Area ◽  
Wide Acceptance

In the 1970s, Japanese cooks began to appear in the kitchens of nouvelle cuisine chefs in France for further training, with scores more arriving in the next decades. Paul Bocuse, Alain Chapel, Joël Robuchon, and other leading French chefs started visiting Japan to teach, cook, and sample Japanese cuisine, and ten of them eventually opened restaurants there. In the 1980s and 1990s, these chefs' frequent visits to Japan and the steady flow of Japanese stagiaires to French restaurants in Europe and the United States encouraged a series of changes that I am calling the “Japanese turn,” which found chefs at fine-dining establishments in Los Angeles, New York City, and later the San Francisco Bay Area using an ever-widening array of Japanese ingredients, employing Japanese culinary techniques, and adding Japanese dishes to their menus. By the second decade of the twenty-first century, the wide acceptance of not only Japanese ingredients and techniques but also concepts like umami (savory tastiness) and shun (seasonality) suggest that Japanese cuisine is now well known to many American chefs.

scholarly journals Standing on the shoulders of Giants: a citation analysis of the paediatric congenital heart disease literature

2021 ◽  
pp. 1-9
Author(s):  
Daniel P. Sew ◽  
Nigel E. Drury
Keyword(s):  
Citation Analysis ◽  
San Francisco ◽  
Citation Count ◽  
Case Series ◽  
Scientific Progress ◽  
The United States ◽  
Original Research ◽  
Prolific Author ◽  
Journal Citation Reports ◽  
The Impact

Abstract Objective: The citation history of a published article reflects its impact on the literature over time. We conducted a comprehensive bibliometric analysis to identify the most cited papers on CHD in children. Methods: One-hundred and ninety journals listed in Journal Citation Reports were accessed via Web of Science. Publications with 250 or more citations were identified from Science Citation Index Expanded (1900–2020), and those relating to structural CHD in children were reviewed. Articles were ranked by citation count and the 100 most cited were analysed. Results: The number of citations ranged from 2522 to 309 (median 431, IQR 356–518), with 35 published since 2000. All were written in English, most originated from the United States (74%), and were published in cardiovascular journals, with Circulation (28%) the most frequent. There were 86 original research articles, including 50 case series, 14 cohort studies, and 10 clinical trials. The most cited paper was by Hoffman JI and Kaplan S on the incidence of CHD. Thirteen authors had 4 or more publications in the top 100, all of whom had worked in Boston, Philadelphia, San Francisco, or Dallas, and the most prolific author was Newburger JW (9 articles). Conclusions: Citation analysis provides a historical perspective on scientific progress by assessing the impact of individual articles. Our study highlights the dominant position of US-based researchers and journals in this field. Most of the highly cited articles remain case series, with few randomised controlled trials in CHD appearing in recent years.

scholarly journals Use of Korean dramas to facilitate precision mental health understanding and discussion for Asian Americans

2021 ◽  
Author(s):  
Van My Ta Park ◽  
Cate Jongkyung Park ◽  
Charles Kim ◽  
Nhi Cristina Y Nguyen ◽  
Anh T Tran ◽  
...  
Keyword(s):  
Mental Health ◽  
San Francisco ◽  
Asian Americans ◽  
Health Knowledge ◽  
The United States ◽  
Mental Health Research ◽  
Educational Tool ◽  
Convenience Sample ◽  
Language Groups ◽  
Precision Health

Summary Precision mental health holds great potential for revolutionizing care and reducing the burden of mental illness. All races and ethnicities such as Asian Americans, the fastest growing racial group in the United States (U.S.), need to be engaged in precision mental health research. Owing to its global popularity, Korean drama (‘K-drama’) television shows may be an effective educational tool to increase precision mental health knowledge, attitudes and behaviors among Asian Americans. This qualitative study examined the participants’ perspectives about and acceptance of using K-dramas to educate and engage Asian Americans about precision mental health. Twelve workshops were conducted in English, Vietnamese and Korean with a convenience sample in the San Francisco Bay Area in the U.S. (n = 122). Discussions were coded for themes. Findings revealed that all language groups reported positive reactions to using K-dramas to learn about precision health, genetics and mental health. Overall, participants shared that they learned about topics that are not generally talked about (e.g. precision health; genetic testing; mental health), from other people’s perspectives, and the importance of mental health. Participants expressed how much they enjoyed the workshop, how they felt relieved due to the workshop, thought the workshop was interesting, and had an opportunity for self-reflection/healing. This pilot test demonstrated that K-dramas has promise to be used as a health educational tool in a workshop format focused on mental health among a diverse group of Asian Americans. Given the widespread access to K-dramas, they present a scalable opportunity for increasing awareness about specific health topics.

scholarly journals High food insecurity in Latinx families and associated COVID-19 infection in the Greater Bay Area, California

BMC Nutrition ◽  
2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Milagro Escobar ◽  
Andrea DeCastro Mendez ◽  
Maria Romero Encinas ◽  
Sofia Villagomez ◽  
Janet M. Wojcicki
Keyword(s):  
Food Security ◽  
Food Insecurity ◽  
San Francisco ◽  
Employment Status ◽  
The United States ◽  
Household Food Security ◽  
Bay Area ◽  
Household Food ◽  
History Of ◽  
The Impact

Abstract Background Food insecurity impacts nearly one-in-four Latinx households in the United States and has been exacerbated by the novel coronavirus or COVID-19 pandemic. Methods We examined the impact of COVID-19 on household and child food security in three preexisting, longitudinal, Latinx urban cohorts in the San Francisco Bay Area (N = 375 households, 1875 individuals). Households were initially recruited during pregnancy and postpartum at Zuckerberg San Francisco General Hospital (ZSFG) and UCSF Benioff prior to the COVID-19 pandemic. For this COVID-19 sub-study, participants responded to a 15-min telephonic interview. Participants answered 18 questions from the US Food Security Food Module (US HFSSM) and questions on types of food consumption, housing and employment status, and history of COVID-19 infection as per community or hospital-based testing. Food security and insecurity levels were compared with prior year metrics. Results We found low levels of household food security in Latinx families (by cohort: 29.2%; 34.2%; 60.0%) and child food security (56.9%, 54.1%, 78.0%) with differences between cohorts explained by self-reported levels of education and employment status. Food security levels were much lower than those reported previously in two cohorts where data had been recorded from prior years. Reported history of COVID-19 infection in households was 4.8% (95% Confidence Interval (CI); 1.5–14.3%); 7.2% (95%CI, 3.6–13.9%) and 3.5% (95%CI, 1.7–7.2%) by cohort and was associated with food insecurity in the two larger cohorts (p = 0.03; p = 0.01 respectively). Conclusions Latinx families in the Bay Area with children are experiencing a sharp rise in food insecurity levels during the COVID-19 epidemic. Food insecurity, similar to other indices of poverty, is associated with increased risk for COVID-19 infection. Comprehensive interventions are needed to address food insecurity in Latinx populations and further studies are needed to better assess independent associations between household food insecurity, poor nutritional health and risk of COVID-19 infection.

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