Empirical seismic vulnerability analysis for masonry buildings based on school buildings survey in Iran

School facilities in Iran, in particular masonry schools, have shown poor performance during past earthquakes and can be identified as one of the parts of the country’s infrastructure that is most vulnerable to earthquakes. Hence, in this paper a method to perform index-based damage assessment for brick masonry schools located in the province of Yazd, the central region of Iran, using a comprehensive database of school buildings, is proposed. The database was obtained from the field survey forms applied for each observed school to collect the features of and damage to the structure. The results of a vulnerability index method developed in Iran are employed as input data to obtain empirical fragility curves for the school inventory. The Macroseismic model and GNDT II level method are two empirical methods combined in this procedure. Finally, the procedure is verified using damage survey data obtained after recent earthquakes (1990 Manjil–Rudbar earthquake and 2003 Bam earthquake) that occurred in Iran.     

Is filter packing important in a small-scale vermifiltration process of urban wastewater?

Nowadays, natural resources are under increasing stress which fosters wastewater reuse planning and emphasizes on the decentralized wastewater treatment. Vermifiltration has been described as a viable alternative to treat domestic and urban wastewater, but few studies have focused on the impact of different filter packings on vermifiltration performance. This study evaluates the effect of vermicompost and sawdust in a single-stage vermifilter (VF) for urban wastewater treatment. After an acclimation period of 45 days, urban wastewater from a combined sewage collection system was applied continuously for 24 h. Earthworm stock density was of 20 g L^?1, HRT of 6 h, HLR of 0.89 m³ m^?2 day^?1 and OLR of 7.38 g BOD₅ day^?1. System performance was assessed by the removal efficiencies of BOD₅, COD, TSS, NH₄ ⁺, TN and TP, and fecal coliforms and helminth eggs elimination. Vermicompost (VE) and sawdust (SE) were tested, using an earthworm abundance of 20 g L^?1. Treatment efficiencies were 91.3% for BOD₅, 87.6% for COD, 98.4% for TSS and 76.5% for NH₄ ⁺ in VE, and 90.5% for BOD₅, 79.7% for COD, 98.4% for TSS and 63.4% for NH₄ ⁺ in SE. Earthworms contributed to reduce NH₄ ⁺ and TN removal and to increase NO₃ ^? concentration. No treatment was able to eliminate fecal coliforms down to guidelines values for wastewater irrigation as helminth eggs were completely eliminated. Single-stage vermifiltration system using both filter packings is inconsistent and cannot meet EU guideline values for discharge in sensitive water bodies and WHO guidelines for irrigation with treated wastewater.     

Comparison between rocking analysis and kinematic analysis for the dynamic out‐of‐plane behavior of masonry walls

This paper provides a contribution to the rocking analysis of masonry walls by making a comparison with the kinematic analysis suggested by the Italian code. It is shown that the latter approach is generally over‐conservative and therefore potentially inappropriate for historic buildings, where rehabilitation can be expensive and can affect their cultural value. The equation of motion given by the Housner formulation, corresponding to the movement of a rigid block, is here modified to account for different boundary conditions at different heights of the wall. These boundary conditions or horizontal restraints can represent vaults, transverse walls, or retrofitting devices such as steel tie‐rods. A systemic analysis of walls having different dimensions and slenderness is performed, and the results from the Italian code and rocking analysis are compared. Finally, the improvement in the response offered by retrofitting devices is discussed in terms of reduction of amplitude ratio. Copyright © 2015 John Wiley & Sons, Ltd.     

Morpho-tectonic analysis of the Azores Volcanic Plateau from a new bathymetric compilation of the area

The existing studies of the Azores triple junction, although based on specific geological or geophysical data, largely rely upon morphological considerations. However, there is no systematic bathymetric coverage of this area, and the quality of the available bathymetric charts does not allow consistent morpho-structural analysis.In this work we present a new bathymetric grid elaborated with all the available data sources in an area comprised between 24° W to 32° W and 36° N to 41° N. The basic data set corresponds to the merge of NGDC data with new swath profiles. This new map, included as an Appendix, combined with other results from seismology and neotectonics, is the basis for the study of the morpho-structural pattern of the Azores area, the present day stress field and its implications on the current view of the Azores geodynamics.As a major result, we conclude that the Azores region is controlled by two sets of conjugated faults with 120° and 150° strikes that establish the framework for the onset of volcanism, expressing as linear volcanic ridges or as point source volcanism. This interaction develops what can be considered as the morphological signature of the Azores Spreading axis segmentation. We argue that the Azores domain, presently in a broad transtensional regime, is acting simultaneously as a ultra slow spreading centre and as a transfer zone between the MAR and the dextral Gloria Fault, as it accommodates the differential shear movement between the Eurasian and African plates.     

Mapping soil pollution by spatial analysis and fuzzy classification

Spatial analysis and fuzzy classification techniques were used to estimate the spatial distributions of heavy metals in soil. The work was applied to soils in a coastal region that is characterized by intense urban occupation and large numbers of different industries. Concentrations of heavy metals were determined using geostatistical techniques and classes of risk were defined using fuzzy classification. The resulting prediction mappings identify the locations of high concentrations of Pb, Zn, Ni, and Cu in topsoils of the study area. The maps show that areas of high pollution of Ni and Cu are located at the northeast, where there is a predominance of industrial and agricultural activities; Pb and Zn also occur in high concentrations in the northeast, but the maps also show significant concentrations of Pb and Zn in other areas, mainly in the central and southeastern parts, where there are urban leisure activities and trade centers. Maps were also prepared showing levels of pollution risk. These maps show that (1) Cu presents a large pollution risk in the north–northwest, midwest, and southeast sectors, (2) Pb represents a moderate risk in most areas, (3) Zn generally exhibits low risk, and (4) Ni represents either low risk or no risk in the studied area. This study shows that combining geostatistics with fuzzy theory can provide results that offer insight into risk assessment for environmental pollution.     

Late Pleistocene raised beaches of coastal Estremadura,central Portugal

We present new stratigraphic, sedimentological, and chronological data for a suite of tectonically raised beaches dating to Marine Isotope Stages 5, 4, and 3 along the Estremadura coast of west-central Portugal. The beach deposits are found in association with ancient tidal channels and coastal dunes, pollen bearing mud and peat, and Middle Paleolithic archaeological sites that confirm occupation of the coastal zone by Neanderthal populations. The significance of these deposits is discussed in terms of the archaeological record, the tectonic and geomorphic evolution of the coast, and correlation with reconstructions of global climate and eustatic sea-level change. Direct correlation between the Estremadura beach sections is complicated by the tectonic complexity of the area and the age of the beach deposits (which are near or beyond the limit of radiocarbon dating). Evidence from multiple sites dated by AMS radiocarbon and optical luminescence methods suggests broad synchroneity in relative sea-level changes along this coast during Marine Isotope Stage 3. Two beach complexes with luminescence and radiocarbon age control date to about 35 ka and 42 ka, recording a rise in relative sea level around the time of Heinrich Event 4 at 39 ka. Depending on assumptions about eustatic sea level at the time they were deposited, we estimate that these beaches have been uplifted at rates of 0.4–4.3 mm yr^?1 by the combined effects of tectonic, halokinetic, and isostatic processes. Uplift rates of 1–2 mm yr^?1 are likely if the beaches represent sea level stands at roughly 40 m below modern, as suggested by recent eustatic sea level reconstructions. Evidence from coastal bluffs and the interior of the study area indicates extensive colluvial, fluvial, and aeolian sedimentation beginning around 31 ka and continuing into the Holocene. These geomorphic adjustments are related to concomitant changes in climate and sea level, providing context that improves our understanding of Late Pleistocene landscape change and human occupation on the western Iberian margin.     

Hydromechanical Analysis of Masonry Gravity Dams and their Foundations

A numerical model for the hydromechanical analysis of masonry dams based on the discrete element method is presented. The dam and the rock foundation are represented as block assemblies, and a coupled flow-stress analysis is performed in an integrated manner for the entire system. Complex block shapes may be obtained by assembling elementary blocks into macroblocks, allowing the application of the model to situations ranging from equivalent continuum to fully discontinuum analysis. A contact formulation was developed based on an accurate edge–edge approach, incorporating mechanical and hydraulic behavior. The main numerical aspects are described, with an emphasis in the flow analysis explicit algorithm. An application to an existing masonry dam is presented, analyzing its present condition, with excessive seepage, and the proposed rehabilitation intervention. An evaluation of sliding failure mechanisms was also performed, showing the expected improvement in the safety of the structure.     

Spatio-Temporal Patterns of Submerged Macrophytes in Three Hydrologically Altered Mediterranean Coastal Lagoons

Rice cultivation in the Ebro Delta (Catalonia, Spain) has inverted the natural hydrological cycles of coastal lagoons and decreased water salinities for over 150 years. Adjustments in the water management practices—in terms of source and amount of freshwater inputs—have resulted in changes in the diversity, distribution and productivity of submerged angiosperms. Between the 1970s and late 1980s, a massive decline of the aquatic vegetation occurred in the Encanyissada–Clot and Tancada lagoons, but little information on the status is available after the recovery of macrophytes in the 1990s. Here, we evaluate the influence of salinity regimes resulting from current water management practices on the composition, distribution, seasonal abundance and flowering rates of submersed macrophytes, as well as on the occurrence of epiphyte and drift macroalgae blooms in three coastal lagoons. Our results show that Ruppia cirrhosa is the dominant species in the Encanyissada lagoon (185.97?±?29.74 g?DW?m^?2?year^?1; 12–27?‰ salinity) and the only plant species found in the Tancada lagoon (53.26?±?10.94 g?DW?m²?year^?1; 16–28?‰ salinity). Flowering of R. cirrhosa (up to 1,011?±?121 flowers?m^?2) was only observed within the Encanyissada and suggests that mesohaline summer conditions may favor these events. In contrast, low salinities in Clot lagoon (～3–12?‰) favor the development of Potamogeton pectinatus (130.53?±?13.79 g?DW?m²?year^?1) with intersperse R. cirrhosa (8.58?±?1.71 g?DW?m^?2) and mixed stands of P. pectinatus and Najas marina (up to ～57 g?DW?m^?2?year^?1) in some reduced areas. The peak biomasses observed during the study are 88 to 95 % lower than maximum values reported in the literature at similar salinities, and there is also little or no recovery in some areas compared to last reports more than 20 years ago. The main management actions to restore the natural diversity and productivity of submersed angiosperms, such as the recovering of the seagrass Zostera noltii, should be the increase of salinity during the period of rice cultivation, by reducing freshwater inputs and increasing flushing connections with the bays.     

Effects of alkaline-activated fly ash and Portland cement on soft soil stabilisation

This paper studies the effects of sodium-based alkaline activators and class F fly ash on soil stabilisation. Using the unconfined compressive strength test (UCS), the effectiveness of this binder is compared with that of a common cement-based binder. Influence of the activator/ash ratio, sodium oxide/ash ratio and sodium hydroxide concentration was also analysed. Sodium hydroxide concentrations of 10, 12.5 and 15 molal were used for the alkaline-activated specimens (AA), with activator/ash ratios between 1 and 2.5 and ash percentages of 20, 30 and 40 %, relatively to the total solids (soil + ash). UCS was determined at curing periods of 7, 28, 90 and 365 days, and the most effective mixtures were analysed for mineralogy with XRD. The results showed a clear increase in strength with decreasing activator/ash ratio (up to a maximum of 43.4 MPa), which is a positive result since the activator is the most expensive component in the mixture. Finally, UCS results of the cement and AA samples, at 28 days curing, were very similar. However, AA results proved to be just between 20 and 40 % of the maximum UCS obtained at 1 year curing, while cement results at 28 days are expected to be between 80 and 90 % of its maximum.