Displacement-based design of steel moment resisting frames with partially-restrained beam-to-column joints

This article presents a method for the direct displacement-based design of steel moment resisting frames, with specific consideration of beam-to-column joint characteristics. The method can be used for steel frames having any type of beam-to-column joints, from rigid and full-strength to semi-rigid and partial-strength. The plastic rotation capacity of the joints is explicitly taken into account within the performance criteria for the design. To assess the accuracy of the method in controlling performance, case study structures were first designed and subsequently analysed using non-linear dynamic analysis with a set of real accelerograms. For all cases, the mean of peak inter-storey drift demands and the mean of peak plastic rotation demands on joints were controlled in accordance with the limits set during design. The results obtained demonstrate that the proposed method is appropriate for the performance-based seismic design of steel moment resisting frames with different joint typologies.     

Messinian deposits and erosion in northern Tunisia: inferences on Strait of Sicily during the Messinian Salinity Crisis

Outcrops, offshore wells, electric logs and seismic profiles from northern Tunisia provide an opportunity to decipher the Messinian Salinity Crisis in the Strait of Sicily. Messinian deposits (including gypsum beds) near the Tellian Range reveal two successive subaerial erosional surfaces overlain by breccias and marine Zanclean clays, respectively. In the Gulf of Tunis, Messinian thick evaporites (mostly halite) are strongly eroded by a fluvial canyon infilled with Zanclean clays. The first erosional phase is referred to the intra-Messinian tectonic phase and is analogous to that found in Sicily. The second phase corresponds to the Messinian Erosional Surface that postdates the marginal evaporites, to which the entire Sicilian evaporitic series must refer. The Western and Eastern Mediterranean basins were separated during deposition of the central evaporites.     

X-ray Computed Tomography study of the influence of consolidants on the hydric properties of sandstones for stone conservation studies

X-ray Computed Tomography (X-ray CT) has been used to study the petrophysical characteristics of a Jurassic sandstone from Asturias (Northern Spain) used as building stone in several monuments in the region. CT monitoring of water capillarity tests has made it possible to visualize the movement of water inside the samples, to relate this movement with texture characteristics, and to measure the height reached in successive images, thereby determining the capillary penetration coefficient; based on this coefficient, the effective capillary pore radius has also been estimated. An advantage of the use of CT is that, as the information comes from the sample interior, border effects that can be generated in the external faces can be avoided.The CT was also used to visualize how a commercial organosilicon consolidant penetrates inside the rock by means of capillarity, a usual way of consolidant application in stone restoration processes. The coefficient of capillary penetration of the product, determined on the basis of the measurements made on the tomographic images, is 53% less than that of water. The influence of rock texture characteristics on the capillarity both of the consolidant and the water was also observed.The samples underwent CT water capillarity studies before and after the consolidant application, proving that the treatment improves the rock's hydric properties. The coefficient of capillary penetration decreased by 24% following the application of the consolidant, whereas the effective pore radius decreased by more than 40%.     

Valorization of olive stone as adsorbent of chromium(VI): comparison between laboratory- and pilot-scale fixed-bed columns

The main aim of this work is to study the effect of scaling in the biosorption of chromium(VI) onto olive stone in two different fixed-bed columns. Firstly, the effect of flow rate, bed depth and inlet concentration of Cr(VI) in both columns was analyzed. The results revealed a better operation for lower flow rates, higher bed heights and lower inlet concentrations of metal. When decreasing flow rate, the operation time of the column increases. Therefore, as the solution flow rate increased the breakthrough and the exhaustion times decreased. An increase in bed depth increases the quantity of chromium eliminated and thus, the higher sorption capacity of the system. A decrease in the inlet concentration of chromium produces a delay in exhaustion time, and larger volumes of solution could be treated. The results were fitted to the BDST model, obtaining that the adsorptive capacity of the bed depth is similar in laboratory- and pilot-scale fixed-bed columns, considering the biosorption capacity as a biosorption-coupled reduction process. Results also could indicate that scaling affects more to the reduction process than properly biosorption process. The experimental data were also fitted to Adams–Bohart, Thomas, Yoon–Nelson and dose–response models. A good fit of the biosorption process of Cr(VI) was found for dose–response and Adams–Bohart models.     

Surface evolution of salt‐encrusted playas under extreme and continued dryness

Miocene continental saltpans are scattered in the Central Valley of the Atacama Desert, one of the driest regions on Earth. These evaporitic deposits are hydrologically inactive, and are detached from groundwater brines or aquifers. The surface of the saltpans, also known as salars, comprises desiccation polygons, commonly with nodular salt structures along their sides. The morphology and bulk mineralogy of salt polygons differs between and within salars, and the shape and internal structure of salt nodules varies between different polygon types. Based on field observation, and mineralogy and crystallography data, we generated a conceptual model for the genesis and evolution of these surface features, whereby rare rainfall events are responsible for the transformation of desiccation salt polygons and the initial formation of salt nodules along polygon borders. In addition, frequent, but less intense, deliquescence events further drive the evolution of salt nodules, resulting in a characteristic internal structure that includes laminations, and changes in porosity and crystal morphologies. As a result, and despite the extreme dryness, the surfaces of fossil salars are dynamic on timescales of several years to decades, in response to daily cycles in atmospheric moisture, and also to rare and meager rainfall events. We propose that fossil salars in the Atacama Desert represent an end stage in the evolution of evaporitic deposits under extreme and prolonged dryness. Copyright © 2015 John Wiley & Sons, Ltd.     

A less disastrous disaster: Managing response to climate-driven hazards in the Cayman Islands and NE Brazil

This paper explores the relationship between disaster risk reduction and long-term adaptive capacity building in two climate vulnerable areas—the Cayman Islands in the Caribbean and Ceará, in NE Brazil. Drawing on past applications of the disaster risk reduction framework, we identify four critical factors that have led to reductions in risk: flexible, learning-based, responsive governance; committed, reform-minded and politically active actors; disaster risk reduction integrated into other social and economic policy processes; and a long-term commitment to managing risk. We find that while the presence of these factors has reduced overall risk in both regions, in Ceará, disaster response as it is currently practiced, has fallen short of addressing the fundamental causes of vulnerability that leave those prone to hazards able to cope in the short term, yet enmeshed in poverty and at risk from the longer-term changes associated with climate change. Although calls for integration of disaster risk management with poverty eradication are not new, there has been insufficient attention paid in the literature on how to foster such integration. Based on the two case studies, we argue that the adoption of good governance mechanisms (such as stakeholder participation, access to knowledge, accountability and transparency) in disaster risk reduction policy may create the policy environment that is conducive to the kind of structural reform needed to build long-term adaptive capacity to climate-driven impacts. We conclude that without a synergistic two-tiered approach that includes both disaster risk reduction and structural reform, disaster risk reduction, in the face of climate changes, will prove to be an expensive and ineffective palliative treatment of changing risks.     

Determination of Carbon,Hydrogen, Nitrogen and Sulfur in Geological Materials Using Elemental Analysers

This article describes a series of methods developed for the determination of total carbon (C_Total), organic carbon (C_org), hydrogen, nitrogen and sulfur. The following elemental analysers were used: LECO model RC‐412 for the determination of organic carbon, total carbon and hydrogen; LECO model CS‐200 for the determination of total carbon and sulfur; LECO model TN‐400 for the determination of nitrogen; and LECO model TruSpec CHNS for the determination of organic carbon, total carbon, hydrogen, nitrogen and sulfur. Uncertainty and limits of detection and quantification were calculated for each method, as well as the running costs to define the most effective instrument for each material and each analyte. Accuracy was checked by the application of the Sutarno–Steger test. Finally, a compilation of the results obtained in the determination of C_Total, C_org, H, N and S in forty‐nine reference materials is presented.     

Micas of the muscovite-lepidolite series from the fregeneda pegmatites (Salamanca,Spain)

Summary In the Fregeneda area different types of pegmatites can be recognized by their mineralogy, morphology, internal structure and field relationships. The most common type corresponds to a simple pegmatite with homogeneous internal structure, but zoned Li-bearing pegmatites also are relatively widespread. Cassiterite-bearing pegmatites are subordinate. The pegmatites are spatially associated to the Lumbrales granite. This is a parautochthonous, fine- to medium-grained, two-mica granite, one of the syntectonic massifs which were deformed during the third phase of Hercynian deformation. Representative micas selected from the different groups of pegmatites were studied to determine wether the pegmatites can be related by a common fractionation path, and how different pegmatite types are related to the spatially associated Lumbrales granite. Compositional variations in the micas depend on the pegmatite type. Muscovite coexisting with Li-micas in the Li-bearing pegmatites is one of the richest in Al₂O₃ (35.4–37.7 wt%) and the poorest in FeO (0.2–1.5 wt%) and MgO (0–0.3 wt%), whereas muscovite of the simple discordant pegmatites shows the highest FeO (2.2–3.3 wt%) and that from the Lumbrales granite is the richest in MgO (0.5–0.7 wt%) and TiO₂ (0.6–1.1 wt%). On the other hand, Sn (70–1168 ppm), Li (< 5–22253 ppm), F (880–21470 ppm), Cs (< 5–1696 ppm), Rb (800–9181 ppm) and other trace elements seem to increase with distance from the Lumbrales granite, and K/Rb decreases. According to this ratio, the exterior Li-bearing pegmatites are the more evolved, whereas the interior pegmatites are less evolved, and are richer in Cs, Li and Zn than other pegmatite types.

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Glimmerminerale der Muscovit-Lepidolith-Serie aus den Pegmatiten von Fregeneda, Salamanca, Spanien

Zusammenfassung Im Gebiet von Fregeneda sind auf Grund ihrer Mineralogie, Morphologie, Internstruktur und Geländebeziehungen verschiedene Pegmatittypen zu unterscheiden. Am häufigsten sind einfache homogen aufgebaute Pegmatite. Zonar gebaute Li-Pegmatite sind ebenfalls weit verbreitet, Zinnstein-führende Pegmatite treten hingegen zurück, Die Pegmatite sind räumlich mit dem Lumbrales Granit, einem paraautochtonen, fein- bis mittelkörnigen Zwei-Glimmergranit, assoziiert, Dieser gehört einem der syntektonischen Massive, die während der dritten Phase der hercynischen Deformation deformiert wurden, an. Repräsentative, aus den verschiedenen Pegmatittypen separierte Glimmerminerale wurden untersucht, um zu klären, inwieweit die Pegmatite über einen direkten Fraktionierungspfad zu verbinden sind und in welcher Beziehung sie zu dem Lumbrales Granit stehen. Die Variation der Zusammensetzung der Glimmer hängt vom Pegmatittyp ab. Muscovite, die mit Li-Glimmern koexistieren, sind die relativ Al₂O₃-reichsten (32–37.7 Gew.%) und Fe- (0.2–1.5 Gew.%.) und Mg-ärmsten (0–0.3 Gew.%). Jene aus dem Lumbrales Granit sind die reich an MgO (0.5–0.7) und TiO₂ (0.6–1.1 Gew.%). Die Gehalte von Sn (70–1168 ppm), Li (< 5–22253 ppm). F (880-21470 ppm), Cs (< 5–1696 ppm), Rb (800–9181 ppm) und anderer Spurenelemente nehmen mit der Entfernung vom Lumbrales Granit zu, während K/Rb abnimmt. Auf Grund dieses Verhältnisses sind die externen Li-führenden Pegmatite höher, die internen Pegmatite hingegen geringfügiger entwickelt. Erstere sind daher auch reicher an Cs, Li und Zn.

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With 4 Figures