Design S-N curves for old Portuguese and French riveted bridges connection based on statistical analyses

Maintenance of ancient road and railway metallic bridges has become a major concern for governmental agencies in the past few decades. Indeed, since the construction of these structures, between the end of the 19th century and the beginning of the 20th century, traffic conditions have evolved, both in weight and frequency. In the purpose to assess the remaining life of old metallic bridges, some critical structural details have been identified and associated to S-N curves in order to be used in damage estimation (using Palmgren-Miner’s rule for cumulative damage, for example). These constructional details are described by design rules of several European and North American standards, such as the Eurocode 3, BS 5400 and AASHTO standards. The particularity of ancient bridges is that hot riveted assemblies, commonly used for their construction, are not represented in most construction standards. Further experiences on the matter by numerous research teams have suggested detail category C71 from the Eurocode 3 as appropriate. In this paper, experimental data from double shear assemblies manufactures from three different metallic ancient bridges is used to identify, through a statistical analysis, the S-N curves that best fit this constructional detail. Portuguese and French puddled iron bridges were considered.The authors of this paper thank the National Society of French Railways and the SciTech - Science and Technology for Competitive and Sustainable Industries, R&D project NORTE-01-0145-FEDER-000022 cofinanced by Programa Operacional Regional do Norte ("NORTE2020"), through Fundo Europeu de Desenvolvimento Regional (FEDER) for their collaboration and support during this research works. The authors also acknowledge the Portuguese Science Foundation (FCT) for the financial support through the post-doctoral grant SFRH/BPD/107825/2015

Intermittent existence of a southern Californian upwelling cell during submillennial climate change of the last 60 kyr

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95021/1/palo1108.pd

The sinaps french research project first lessons of an integrated seismic risk assessment for nuclear plants safety

International audienceWhatever the level of seismicity of a country, the seismic risk has to be assessed and accounted in the frame ofnuclear plant safety, from its design, during its operational as well as dismantling phases. The seismic risk assessmentcombines the seismic hazard and the seismic vulnerability of the civil engineering and equipment estimates. Acceptablemethods to perform seismic risk analyses are guided by international references, such as the Safety Guides andRequirements published by the International Atomic Energy Agency (IAEA) but also by national documents. The currentmethodologies used in France to assess the seismic hazard are firstly the scenario-based approach proposed in the FrenchFundamental Safety Rule (RFS 2001-01), and secondly the ASN/2/01 Guide providing design rules of nuclear civilengineering structures. These references were respectively updated by the Nuclear Safety Authority in 2001 and 2006. Sincethen, the 2011 Tohoku earthquake that triggered a huge tsunami caused the severe accident at the Fukushima Daïchi nuclearplant. The analysis of the observations demonstrated that the seismic and tsunami hazards were underestimated for thisregion. Consequently worldwide nuclear operators were asked by their authority to perform “stress tests” to estimate theirplant capacity sustaining extreme seismic loadings. In this framework, an 5 years research project called SINAPS@(Earthquake and Nuclear Installations: Ensuring and Sustaining Safety) is on-going in France. SINAPS@ brings together amultidisciplinary community of researchers and engineers, funding also 12 Ph.D. and 19 post-doctoral researchers.SINAPS@ aims at conducting a continuous analysis of completeness and gaps in data bases (all data types, from geology,seismology, site characterization and materials), of the reliability or deficiency of models available to describe physicalphenomena (prediction of seismic motion, site effects, soil and structure interaction, linear and nonlinear wave propagation,materials constitutive laws in nonlinear domain), and of the relevance or weakness of methodologies used to performedseismic risk assessment. This critical analysis conducted confronting methods, either deterministic or probabilistic, andavailable data to the international state of the art systematically addresses the uncertainties issue, should improve theseismic margins assessment. The present contribution will expose the first lessons learned from SINAPS@ few 18 monthsbefore its end

High primary productivity in an ice melting hot spot at the eastern boundary of the Weddell Gyre

The Southern Ocean (SO) plays a key role in modulating atmospheric CO 2 via physical and biological processes. However, over much of the SO, biological activity is iron-limited. New in situ data from the Antarctic zone south of Africa in a region centered at ~20°E-25°E reveal a previously overlooked region of high primary production, comparable in size to the northwest African upwelling region. Here, sea ice together with enclosed icebergs is channeled by prevailing winds to the eastern boundary of the Weddell Gyre, where a sharp transition to warmer waters causes melting. This cumulative melting provides a steady source of iron, fuelling an intense phytoplankton bloom that is not fully captured by monthly satellite production estimates. These findings imply that future changes in sea-ice cover and dynamics could have a significant effect on carbon sequestration in the SO