Seismic performance of a 1 : 15‐scale 25‐story RC flat‐plate core‐wall building model

Earthquake simulation tests were conducted on a 1 : 15‐scale 25‐story building model to verify the seismic performance of high‐rise reinforced‐concrete flat‐plate core‐wall building structures designed per the recent seismic code KBC 2009 or IBC 2006. The following conclusions can be drawn from the test results: (1) The vertical distribution of acceleration during the table excitations revealed the effect of the higher modes, whereas free vibration after the termination of the table excitations was governed by the first mode. The maximum values of base shear and roof drift during the free vibration are either similar to or larger than the values of the maximum responses during the table excitation. (2) With a maximum roof drift ratio of 0.7% under the maximum considered earthquake in Korea, the lateral stiffness degraded to approximately 50% of the initial stiffness. (3) The crack modes appear to be a combination of flexure and shear in the slab around the peripheral columns and in the coupling beam. Energy dissipation via inelastic deformation was predominant during free vibration after the termination of table excitation rather than during table excitation. Finally, (4) the walls with special boundary elements in the first story did not exhibit any significant inelastic behavior, with a maximum curvature of only 21% of the ultimate curvature, corresponding to an ultimate concrete compressive strain of 0.00638 m/m intended in the displacement‐based design approach. Copyright © 2014 John Wiley & Sons, Ltd.     

Up‐scaling potential impacts on water flows from agricultural water interventions: opportunities and trade‐offs in the Osman Sagar catchment,Musi sub‐basin,India

Agricultural water management (AWM) has been shown to improve and secure yields in the tropics and has been suggested as an important way to combat poverty in the region. In this paper, we describe potential impacts on upstream and downstream flows of extensive AWM interventions, using the watershed development programme of the Osman Sagar catchment of Musi sub‐basin, Andhra Pradesh semi‐arid India, as an example. Various AWM interventions are compared with a non‐intervention state and the current state of the study area, using 31 years of data by application of the calibrated and validated ARCSWAT 2005 (Version 2.1.4a) modelling tool. Different AWM interventions contribute to improved livelihoods of upstream smallholder farmers by increasing soil moisture availability and groundwater recharge, which can subsequently be used for irrigation. The result is higher crop production and hence larger incomes. Moreover, lower flow intensities and sediment losses reduced by 30–50%, reducing the risk of flooding and sediment accumulation in the Osman Sagar drinking water reservoir. On the other hand, AWM interventions are predicted to result in reduced total water inflows to the Osman Sagar reservoir from 11% of the total annual rainfall (754 mm) recorded at present, to 8% if AWM interventions were implemented at large scale throughout the catchment. A cost–benefit analysis of AWM interventions showed that the highest net economic returns were achieved at intermediate intervention levels (only in‐situ AWM). Copyright © 2012 John Wiley & Sons, Ltd.     

Spatial and temporal variability of 0‐ to 5‐m soil–water storage at the watershed scale

Dynamic relationships among rainfall patterns, soil water distribution, and plant growth are crucial for sustainable conservation of soil and water resources in water‐limited ecosystems. Spatial and temporal variation in deep soil water content at a watershed scale have not yet been characterized adequately due to the lack of deep soil water data. Deep soil–water storage (SWS) up to a depth of 5 m (n = 73) was measured at 19 sampling occasions at the LaoYeManQu watershed on the Chinese Loess Plateau (CLP). At a depth of 0–1.5 m, the annual mean SWS was highly correlated with rain intensity, and the correlation decreased with depth, but within the layers at 1.5–5.0 m, the changes in SWS indicated a lag between precipitation and the replenishment of soil water. Geostatistical parameters of SWS were also highly dependent on depth, and the mean SWS presented similar spatial structures in two adjacent layers. Temporal stability of SWS as indicated by mean relative difference, standard deviation of the relative difference (SDRD), and mean absolute bias error (MABE) was significantly weaker at the shallow than at deeper layers. Soil separates and organic carbon content controlled the spatial pattern of SWS at the watershed scale. One representative location (Site 57) was identified to estimate the mean SWS in the 1‐ to 5‐m layer of the watershed. Semivariograms of the SDRD and MABE were best fitted by an isotropic spherical model, and their spatial distributions were depth‐dependent. Both temporal stability and spatial variability of SWS increased over depth. This study is helpful for deep SWS estimation and sustainable management of soil and water on the CLP, and for other similar regions around the world.     

Influence of Surfactants on Degradation of 1‐(2‐Chlorobenzoyl)‐3‐(4‐chlorophenyl) Urea by Nanoscale Zerovalent Iron

Nanoscale zerovalent iron (NZVI) has been proved to be effective in the degradation of environmental pollutants and exhibits advantages in the removal of 1‐(2‐chlorobenzoyl)‐3‐(4‐chlorophenyl) urea (CCU), an analog of diflubenzuron. This present study focused on the influence of surfactants in the degradation procedure with NZVI in order to provide a simple and rapid removal method for CCU. Triton X‐100, Tween 20, Tween 80, sodium dodecyl sulfonate (SDS), and cetyltrimethylammonium bromide (CTAB) were investigated under anaerobic conditions. The experimental results demonstrated that the degradation rate increased sharply with the presence of SD during the first 15 min, up to 99.97% with addition of 0.01 g L^?1 SDS, whereas the presence of Triton X‐100, Tween 80, and Tween 20 resulted in a slight enhancement of the degradation of CCU. The enhancement strength of them was in the order Tween 20, Triton X‐100, and Tween 80. However, addition of the cationic surfactant CTAB resulted in a significant inhibitive effect. In contrast, the mixed surfactants did not result in the expected performance, and the performance was lower than that using some certain single surfactant among the mixed surfactants.     

Earthquake soil‐structure interaction of nuclear power plants,differences in response to 3‐D, 3 × 1‐D,and 1‐D excitations

In soil‐structure interaction modeling of systems subjected to earthquake motions, it is classically assumed that the incoming wave field, produced by an earthquake, is unidimensional and vertically propagating. This work explores the validity of this assumption by performing earthquake soil‐structure interaction modeling, including explicit modeling of sources, seismic wave propagation, site, and structure. The domain reduction method is used to couple seismic (near‐field) simulations with local soil‐structure interaction response. The response of a generic nuclear power plant model computed using full earthquake soil‐structure interaction simulations is compared with the current state‐of‐the‐art method of deconvolving in depth the (simulated) free‐field motions, recorded at the site of interest, and assuming that the earthquake wave field is spatially unidimensional. Results show that the 1‐D wave‐field assumption does not hold in general. It is shown that the way in which full 3‐D analysis results differ from those which assume a 1‐D wave field is dependent on fault‐to‐site geometry and motion frequency content. It is argued that this is especially important for certain classes of soil‐structure systems of which nuclear power plants subjected to near‐field earthquakes are an example.     

3‐D shallow‐water seismic survey evaluation and design using the focal‐beam method: a case study offshore Abu Dhabi

For 3‐D shallow‐water seismic surveys offshore Abu Dhabi, imaging the target reflectors requires high resolution. Characterization and monitoring of hydrocarbon reservoirs by seismic amplitude‐versus‐offset techniques demands high pre‐stack amplitude fidelity. In this region, however, it still was not clear how the survey parameters should be chosen to satisfy the required data quality. To answer this question, we applied the focal‐beam method to survey evaluation and design. This subsurface‐ and target‐oriented approach enables quantitative analysis of attributes such as the best achievable resolution and pre‐stack amplitude fidelity at a fixed grid point in the subsurface for a given acquisition geometry at the surface. This method offers an efficient way to optimize the acquisition geometry for maximum resolution and minimum amplitude‐versus‐offset imprint. We applied it to several acquisition geometries in order to understand the effects of survey parameters such as the four spatial sampling intervals and apertures of the template geometry. The results led to a good understanding of the relationship between the survey parameters and the resulting data quality and identification of the survey parameters for reflection imaging and amplitude‐versus‐offset applications.