Experimental study on the bidirectional inelastic deformation capacity of U‐shaped steel dampers for seismic isolated buildings

Hysteretic dampers are used to dissipate earthquake‐induced energy in base‐isolated structures by acquiring inelastic deformations, rendering their hysteretic behavior of vital importance. The present paper focuses on investigating the behavior of U‐shaped steel dampers under bidirectional loading; this is significantly different from their corresponding uniaxial behavior. Two main sets of loading tests on full‐scale specimens are conducted in this regard: (i) quasi‐static tests with simple histories and (ii) dynamic tests with realistic loading histories. Based on the results obtained in the quasi‐static tests, an interaction curve that accounts for the reduction of the cyclic deformation capacity is proposed. However, the fidelity of this relation must be assessed under loading conditions similar to those of a seismically isolated structure subjected to an earthquake, which represents the goal of the second set of tests. The results of the dynamic tests validate the proposed interaction curve for estimating the deformation capacity of U‐shaped steel dampers under bidirectional loading. Copyright © 2015 John Wiley & Sons, Ltd.     

Full-scale dynamic testing of response-controlled buildings and their components: concepts,methods, and findings

A series of shake-table tests was conducted by inserting and replacing 4 different types of dampers, or by removing them in a full-scale 5-story steel frame building. The objective is to validate response-control technologies that are increasingly adopted for major Japanese buildings without being attested to-date by a major earthquake. Test results are briefly described, and good performance of the dampers and frame demonstrated. The concepts of the full-scale building tests and various contributions are discussed. The difficulty associated with full-scale dynamic testing is explained.     

Detection and temporal variation of Co in the digestive glands of the common octopus, Octopus vulgaris, in the East China Sea

⁶⁰Co were detected in common octopus specimens collected in the East China Sea in 1996-2005. The source of ⁶⁰Co has remained unclear yet. Stable isotope analyses showed that there was no difference in stable Co concentrations between octopus samples with ⁶⁰Co and without ⁶⁰Co. This result showed that the stable Co in the digestive gland of octopus potentially did not include a trace amount of ⁶⁰Co and the source of ⁶⁰Co existed independently. Furthermore, investigations of octopus in other area and other species indicated that the origin of the source of ⁶⁰Co occurred locally in the restricted area in the East China Sea and not in the coastal area of Japan. Concentrations of ⁶⁰Co have annually decreased with shorter half-life than the physical half-life. This decrease tendency suggests that the sources of ⁶⁰Co were identical and were temporary dumped into the East China Sea as a solid waste.     

Influence of shear angle on hangingwall deformation during tectonic inversion

Tectonic inversion is a common phenomenon in island arc settings, especially in back‐arc basins. The reactivation of normal faults as thrusts, triggered by tectonic inversion, produces typical inversion fault‐related folds and thrusts in the hangingwall. These hangingwall inversion geometries are affected by two factors: the geometry of the underlying master fault and the angle of inclined simple shear relative to the regional dip of strata, in the case that the deformation is approximated by simple shear. This study employed numerical simulations to analyse the influence of the antithetic shear angle on the geometry of the hangingwall and displacement along the master fault. The simulation results reveal that a steeply inclined shear vector during extension produces a narrow, steep‐sided half‐graben, whereas a gently inclined shear produces a wide, open basin. After tectonic inversion, a tight anticline is formed under steeply inclined shear, whereas an open anticline is formed under gently inclined shear. Antithetic shear results in reduced total displacement along the master fault, and the greater the angle between the shear direction and the regional dip, the greater the displacement along the master fault. Because the deformation geometry of syn‐extension layers is affected by extension followed by contraction, a change in the shear angle during tectonic inversion produces a wide variety of deformation geometries. Comparison of the simulation results with the results of analogue modelling suggests that the shear angle decreases by 5° during the transition from extension to tectonic inversion and that such a change may be commonly observed in natural geological structures. These results highlight the benefits of numerical simulations, which can be used to readily examine a variety of constraining parameters and thereby lead to a better understanding of the mechanism of hangingwall deformation, avoiding erroneous estimates of the amount of fault displacement.     

Dissecting large earthquakes in Japan: Role of arc magma and fluids

We synthesized information from recent high-resolution tomographic studies of large crustal earthquakes which occurred in the Japanese Islands during 1995–2008. Prominent anomalies of low-velocity and high Poisson's ratio are revealed in the crust and uppermost mantle beneath the mainshock hypocenters, which may reflect arc magma and fluids that are produced by a combination of subducting slab dehydration and corner flow in the mantle wedge. Distribution of 164 crustal earthquakes ( M 5.7–8.0) that occurred in Japan during 1885–2008 also shows a correlation with the distribution of low-velocity zones in the crust and uppermost mantle. A qualitative model is proposed to explain the geophysical observations recorded so far in Japan. We consider that the nucleation of a large earthquake is not entirely a mechanical process, but is closely related to the subduction dynamics and physical and chemical properties of materials in the crust and upper mantle; in particular, the arc magma and fluids.     

Comparative Study on Conservation of Agricultural Heritage Systems in China,Japan and Korea

The paper compares the agricultural heritage conservation schemes of China, Japan and Korea and, in particular, the national programs and their implementation under Food and Agriculture Organization of the United Nations (FAO)’s Globally Important Agricultural Heritage Systems (GIAHS). This comparison allows an understanding of the background of developments, designation criteria, application procedures and implementation structures of GIAHS and of the respective domestic programs in terms of the differences in national circumstances of Japan, China and South Korea. The sequence of implementation of GIAHS and the national program differs in each of the three countries. China introduced a national program after GIAHS designation, Japan has GIAHS but no national program, and Korea implemented a national program before its GIAHS designation. Thus GIAHS candidate sites in China and Korea are now selected from among their respective pools of national agricultural heritage sites. On the other hand, commonalities can be seen in the perspectives of the three countries with regards to agricultural heritage conservation through the common emphasis placed on the designation criteria: historical significance, cultural value, fostering partnerships, rural revitalization and biodiversity conservation associated with the agricultural heritage systems etc. Thus, the cooperation between China, Japan and Korea and the perspectives they have will contribute to proposals for improvements to the FAO designation criteria for GIAHS. These will be comprehensively applicable to both developing and developed countries.     

Mixed Land Use and Obesity: An Empirical Comparison of Alternative Land Use Measures and Geographic Scales

Obesity is a growing epidemic in the United States. Walkable neighborhoods, characterized as having the three Ds of walkability (population Density, land use Diversity, and pedestrian-friendly Design), have been identified as a potentially promising factor to prevent obesity for residents. Past studies examining the relationship between obesity and walkability vary in geographic scales of neighborhood definitions and methods of measuring the three Ds. To better understand potential influences of these sometimes arbitrary choices, we test how four types of alternative measures of land use diversity measured at three geographic scales relate to body mass index for 4,960 Salt Lake County adults. Generalized estimation equation models demonstrate that optimal diversity measures differed by gender and geographic scale and that integrating walkability measures at different scales improved the overall performance of models.     

Mixing of magmatic CO2 into volcano groundwater flow at Aso volcano assessed combining carbon and water stable isotopes

To understand deep groundwater flow systems and their interaction with CO₂ emanated from magma at depth in a volcanic edifice, deep groundwater samples were collected from hot spring wells in the Aso volcanic area for hydrogen, oxygen and carbon isotope analyses and measurements of the stable carbon isotope ratios and concentrations of dissolved inorganic carbon (DIC). Relations between the stable carbon isotope ratio (δ¹³C_DIC) and DIC concentrations of the sampled waters show that magma-derived CO₂ mixed into the deep groundwater. Furthermore, groundwaters of deeper areas, except samples from fumarolic areas, show higher δ¹³C_DIC values. The waters' stable hydrogen and oxygen isotope ratios (δD and δ¹⁸O) reflect the meteoric-water origin of that region's deep groundwater. A negative correlation was found between the altitude of the well bottom and the altitude of groundwater recharge as calculated using the equation of the recharge-water line and δD value. This applies especially in the Aso-dani area, where deeper groundwater correlates with higher recharge. Groundwater recharged at high altitude has higher δ¹³C_DIC of than groundwater recharged at low altitude, strongly suggesting that magmatic CO₂ is present to a much greater degree in deeper groundwater. These results indicate that magmatic CO₂ mixes into deeper groundwater flowing nearer the magma conduit or chamber.     

Phytoplankton productivity in the western subarctic gyre of the North Pacific in early summer 2006

We deployed a profiling buoy system incorporating a fast repetition rate fluorometer in the western subarctic Pacific and carried out time-series observations of phytoplankton productivity from 9 June to 15 July 2006. The chlorophyll a (Chl a) biomass integrated over the euphotic layer was as high as 45–50 mg Chl a m⁻² in the middle of June and remained in the 30–40 mg Chl a m⁻² range during the rest of observation period; day-to-day variation in Chl a biomass was relatively small. The daily net primary productivity integrated over the euphotic layer ranged from 144 to 919 mg C m⁻² day⁻¹ and varied greatly, depending more on insolation rather than Chl a biomass. In addition, we found that part of primary production was exported to a 150-m depth within 2 days, indicating that the variations in primary productivity quickly influenced the organic carbon flux from the upper ocean. Our results suggest that the short-term variability in primary productivity is one of the key factors controlling the carbon cycle in the surface ocean in the western subarctic Pacific.     

Empirical ocean-color algorithms to retrieve chlorophyll-a, total suspended matter, and colored dissolved organic matter absorption coefficient in the Yellow and East China Seas

A bio-optical dataset collected during the 1998?C2007 period in the Yellow and East China Seas (YECS) was used to provide alternative empirical ocean-color algorithms in the retrieval of chlorophyll-a (Chl-a), total suspended matter (TSM), and colored dissolved organic matter (CDOM) absorption coefficients at 440 nm (ag₄₄₀). Assuming that remote-sensing reflectance (Rrs) could be retrieved accurately, empirical algorithms for T_Chl (regionally tuned Tassan??s Chl-a algorithm) in case-1 waters (T_Chl2i in case-2 waters), T_TSM (regionally tuned Tassan??s TSM algorithm), and T_ag440 or C_ag440 (regionally tuned Tassan??s or Carder??s ag₄₄₀ algorithm) were able to retrieve Chl-a, TSM, and ag₄₄₀ with uncertainties as high as 35, 46, and 35%, respectively. Applying the standard SeaWiFS Rrs, T_Chl was not viable in the eastern part of the YECS, which was associated with an inaccurate SeaWiFS Rrs retrieval because of improper atmospheric correction. T_Chl behaved better than other algorithms in the turbid case-2 waters, although overestimation was still observed. To retrieve more reliable Chl-a estimates with standard SeaWiFS Rrs in turbid water (a proxy for case-2 waters), we modified T_Chl for data with SeaWiFS normalized water-leaving radiance at 555 nm (nLw₅₅₅) > 2 mW cm^?2 ??m^?1 sr^?1 (T_Chl2s). Finally, with standard SeaWiFS Rrs, we recommend switching algorithms from T_Chl2s (for case-2 waters) to MOC_Chl (SeaWiFS-modified NASA OC4v4 standard algorithm for case-1 waters) for retrieving Chl-a, which resulted in uncertainties as high as 49%. To retrieve TSM and ag₄₄₀ using SeaWiFS Rrs, we recommend empirical algorithms for T_TSM (pre-SeaWiFS-modified form) and MT_ag440 or MC_ag440 (SeaWiFS Rrs-modified forms of T_ag440 or C_ag440). These could retrieve with uncertainties as high as 82 and 52%, respectively.