Mechanical and low-cycle fatigue behavior of stainless reinforcing steel for earthquake engineering applications

Use of stainless reinforcing steel (SRS) in reinforced concrete (RC) structures is a promising solution to corrosion issues. However, for SRS to be used in seismic applications, several mechanical properties need to be investigated. These include specified and actual yield strengths, tensile strengths, uniform elongations and low-cycle fatigue behavior. Three types of SRSs (Talley S24100, Talley 316LN and Talley 2205) were tested and the results are reported in this paper. They were compared with the properties of A706 carbon reinforcing steel (RS), which is typical for seismic applications, and MMFX II, which is a high strength, corrosion resistant RS. Low-cycle fatigue tests of the RS coupons were conducted under strain control with constant amplitude to obtain strain life models of the steels. Test results show that the SRSs have slightly lower moduli of elasticity, higher uniform elongations before necking, and better low-cycle fatigue performance than A706 and MMFX II. All five types of RSs tested satisfy the requirements of the ACI 318 code on the lower limit of the tensile to yield strength ratio. Except Talley 2205, the other four types of RSs investigated meet the ACI 318 requirement that the actual yield strength does not exceed the specified yield strength by more than 18 ksi (124 MPa). Among the three types of SRSs tested, Talley S24100 possesses the highest uniform elongation before necking, and the best low-cycle fatigue performance.     

Pollen-based continental climate reconstructions at 6 and 21 ka: a global synthesis

Subfossil pollen and plant macrofossil data derived from ¹⁴C-dated sediment profiles can provide quantitative information on glacial and interglacial climates. The data allow climate variables related to growing-season warmth, winter cold, and plant-available moisture to be reconstructed. Continental-scale reconstructions have been made for the mid-Holocene (MH, around 6 ka) and Last Glacial Maximum (LGM, around 21 ka), allowing comparison with palaeoclimate simulations currently being carried out as part of the fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change. The synthesis of the available MH and LGM climate reconstructions and their uncertainties, obtained using modern-analogue, regression and model-inversion techniques, is presented for four temperature variables and two moisture variables. Reconstructions of the same variables based on surface-pollen assemblages are shown to be accurate and unbiased. Reconstructed LGM and MH climate anomaly patterns are coherent, consistent between variables, and robust with respect to the choice of technique. They support a conceptual model of the controls of Late Quaternary climate change whereby the first-order effects of orbital variations and greenhouse forcing on the seasonal cycle of temperature are predictably modified by responses of the atmospheric circulation and surface energy balance.     

Potential mechanistic causes of increased baseflow across northern Eurasia catchments underlain by permafrost

Warming in the Arctic is occurring at twice the rate of the global average, resulting in permafrost thaw and a restructuring of the Arctic hydrologic cycle as indicated by increased stream discharge during low-flow periods. In these cold regions, permafrost thaw is postulated to increase low-flow discharge, or baseflow, through either: (a) localized increases in groundwater storage and discharge to streams due to increased aquifer transmissivity from thickening of the freeze–thaw layer above permafrost known as the active layer or (b) long-term increases in regional groundwater circulation via enhancement of groundwater–surface water interactions due to extensive permafrost loss over decades. While increasing baseflow has been observed throughout northern Eurasia, the precise mechanistic causes remain elusive. In this study, we differentiate between where these two subsurface physical mechanisms of baseflow increase are occurring by performing a baseflow recession analysis using daily streamflow records from 1913 to 2003 for 139 stations in northern Eurasia underlain by varying permafrost areal extents. Results indicate that from 1913 to 2003, the majority of catchments underlain by continuous permafrost have an increasing trend in their recession flow intercepts, a proxy for increasing active layer thickness. Alternatively, the majority of catchments underlain by permafrost types that are less spatially extensive (e.g., discontinuous, sporadic, isolated, or no permafrost) have decreasing trends in their recession flow intercepts, indicating that a potential increase in active layer thickness is not the driving factor of baseflow variations in these catchments. This may indicate that in catchments underlain by continuous permafrost, active layer thickening correlates with increases in baseflow, whereas, in other catchments with less extensive permafrost, increases in baseflow may be caused by wholesale permafrost loss and vertical talik expansion that enhances regional groundwater circulation. The results of this work may inform our understanding of the subsurface mechanisms responsible for the changing Arctic hydrologic cycle.     

Fumarolic activity of Avachinsky and Koryaksky volcanoes, Kamchatka, from 1993 to 1994

 Volcanic gas and condensate samples were collected in 1993–1994 from fumaroles of Koryaksky and Avachinsky, basaltic andesite volcanoes on the Kamchatka Peninsula near Petropavlovsk–Kamchatsky. The highest-temperature fumarolic discharges, 220  °C at Koryaksky and 473  °C at Avachinsky, are water-rich (940–985 mmol/mol of H₂O) and have chemical and isotopic characteristics typical of Kamchatka–Kurile, high- and medium-temperature volcanic gases. The temperature and chemical and water isotopic compositions of the Koryaksky gases have not changed during the past 11 years. They represent an approximate 2 : 1 mixture of magmatic and meteoric end members. Low-temperature, near-boiling-point discharges of Avachinsky Volcano are water poor (≈880 mmol/mol); Their compositions have not changed since the 1991 eruption, and are suggested to be derived from partially condensed magmatic gases at shallow depth. Based on a simple model involving mixing and single-step steam separation, low water and high CO₂ contents, as well as the observed Cl concentration and water isotopic composition in low-temperature discharges, are the result of near-surface boiling of a brine composed of the almost pure condensed magmatic gas. High methane content in low-temperature Avachinsky gases and the 220  °C Koryaksky fumarole, low C isotopic ratio in CO₂ at Koryaksky (–11.8‰), and water isotope data suggest that the "meteoric" end member contains considerable amounts of the regional methane-rich thermal water discovered in the vicinity of both volcanoes. Received: 2 May 1996 / Accepted: 5 November 1996     

A strategy for monitoring of contaminant distributions resulting from proposed sewage sludge disposal at the 106-mile ocean disposal site

It has been proposed that future ocean disposal of sewage sludge from the US east coast be done at a site beyond the edge of the continental shelf. In anticipation of that, a monitoring strategy has been developed to determine the average spatial distribution of contamination. The strategy is an iterative series of measurements developed from models of sludge dispersion and settling which are based on characteristics of the disposal site and sewage sludge. Once disposal is initiated at the site, the strategy requires sampling the upper mixed layer at 36 stations, mostly within 100 km of the site, and deployment of near-bottom sediment traps along a line extending 300 km away from the site. Based on initial results, subsequent sampling locations will be selected to refine estimates of the detectable extent of sludge-derived contamination. The sludge constituents which can be used to detect sludge in water at a dilution of 10⁶ and sludge in sediment traps when diluted by 100 with natural material include zinc, PCBs, coprostanol and spores of the bacterium Clostridium perfringens. Other synthetic organic compounds, besides PCB, may prove to be useful tracers.     

Three-dimensional,periodic, ‘halo’ orbits

A largely numerical study was made of families of three-dimensional, periodic, halo orbits near the collinear libration points in the restricted three-body problem. Families extend from each of the libration points to the nearest primary. They appear to exist for all values of the mass ratio , from 0 to 1. More importantly, most of the families contain a range of stable orbits. Only near L₁, the libration point between the two primaries, are there no stable orbits for certain values of . In that case the stable range decreases with increasing , until it disappears at =0.0573. Near the other libration points, stable orbits exist for all mass ratios investigated between 0 and 1. In addition, the orbits increase in size with increasing .     

“Natural cycles” in lay understandings of climate change

This article analyses lay understandings of climate change elicited through a longitudinal population-based survey of climate change, place and community among 1162 residents in the Hunter Valley, Southeast Australia. We explore how older residents in contrasting rural and coastal geographic areas perceive climate change information in terms of culturally relevant meanings and values, lived experiences and emotional responses to seasonal cycles, temperature fluctuations and altered landscapes. Thematic analysis of comments given by 467 interviewees to an open-ended question identified a significant subset for whom the concepts of “nature” and “science” express competing views about changing climatic conditions. For them, the idea of “natural cycles” is a significant cultural construct that links nature and humans through time in a way that structures stable and resilient understandings of environmental change, drawing on established cosmological frameworks for contemplating the future in relation to the past. In contrast to other studies that postulate scepticism and denial as individuals’ fear management strategies in the face of climate change threat, we found that the natural cycles view is founded on a reassuring deeper conviction about how nature works, and is linked to other pro-environmental values not commonly found in sceptical groups. It is a paradox of natural cycles thinking that it rejects the anthropocentrism that is at the heart of science-based environmentalism. By contrast, it places humans as deeply integrated with nature, rather than operating outside it and attempting with uncertain science to control something that is ultimately uncontrollable.     

Shoreline management in a policy vacuum: A local authority perspective

In Ireland there is no national shoreline management policy. Instead, management involves a series of actions at the local authority (County) level that respond to local demands, politics and economics within only a broad legal framework. Through the COREPOINT project, University of Ulster scientists have been working with local authority officials in Donegal to bring a scientific understanding of coastal processes to bear on practical management. Experience at several sites has shown significant changes in practice as a result of this interaction, compared to the previous situation when rock armouring was the favoured response to coastal erosion. We argue that achieving sustainable approaches to coastal management in a policy vacuum relies on a combination of (i) commitment to these approaches by local officials, (ii) low levels of public pressure for action, and (iii) limited financial resources. A change in any one of these is likely to lead to unsustainable actions. While close co-operation with scientists can help management in the absence of a coherent policy, only a formal regulatory instrument can deliver sustainable shoreline management.     

Paleomagnetic estimate of the emplacement temperature of the long-runout Nevado de Colima volcanic debris avalanche deposit, Mexico

Stoopes and Sheridan have mapped a volcanic debris avalanche of Nevado de Colima which has an exceptionally long runout (120 km) and low fall-height to length ratio (H/L = 0.04). We present paleomagnetic results from this volcanic debris avalanche deposit which provide evidence that this avalanche was emplaced at elevated temperatures. The majority of samples, collected from lithic clasts in the volcanic debris avalanche deposit, exhibit two-component remanent magnetizations with a low-temperature component (25–350°C) which is well grouped about the geomagnetic field direction at Colima and a high-temperature component (350–580°C) which is randomly oriented. Although the temperature of the deposit most likely varied with distance from the volcanic source and the thickness of the deposit, our results suggest an emplacement temperature of approximately 350°C at intermediate distances (18–26 km) from the source. In order for the rock clasts (20–40 cm diameter) to be heated to these temperatures, the avalanche was most likely the results of a magmatic, Bezymianny-type eruption. The mixing of hot, juvenile gases with the clasts provides an explanation for the high degree of fluidization of this material, as evidenced by the long runout of this avalanche deposit.