Determination of ductility factor considering different hysteretic models     

Li Hyung Lee  Sang Whan Han  Young Hun Oh 《地震工程与结构动力学》1999,28(9):957-977

In current seismic design procedures, base shear is calculated by the elastic strength demand divided by the strength reduction factor. This factor is well known as the response modification factor, R, which accounts for ductility, overstrength, redundancy, and damping of a structural system. In this study, the R factor accounting for ductility is called the ‘ductility factor’, R_μ. The R_μ factor is defined as the ratio of elastic strength demand imposed on the SDOF system to inelastic strength demand for a given ductility ratio. The R_μ factor allows a system to behave inelastically within the target ductility ratio during the design level earthquake ground motion. The objective of this study is to determine the ductility factor considering different hysteretic models. It usually requires large computational efforts to determine the R_μ factor. In order to reduce the computational efforts, the R_μ factor is prepared as a functional form in this study. For this purpose, statistical studies are carried out using forty different earthquake ground motions recorded at a stiff soil site. The R_μ factor is assumed to be a function of the characteristic parameters of each hysteretic model, target ductility ratio and structural period. The effects of each hysteretic model to the R_μ factor are also discussed. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

Simultaneous removal of chromium(VI) and Reactive Black 5 using zeolite supported nano-scale zero-valent iron composite     

Seol Ah Kim  S. Kamala-Kannan  Sae-Gang Oh  Min Cho  Sunyoung Bae  Byung-Taek Oh 《Environmental Earth Sciences》2016,75(5):447

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Analytical and statistical approach for evaluating the effects of a river barrage on river–aquifer interactions          下载免费PDF全文

Yun‐Yeong Oh  Se‐Yeong Hamm  Heesung Yoon  Gyoo‐Bum Kim 《水文研究》2016,30(21):3932-3948

The construction of a river barrage can increase groundwater levels upstream of the barrage during the rainy season. Analytical and statistical approaches were applied to evaluate the relationship between groundwater and river water at the Changnyeong–Haman river barrage in Korea using time series data of water level and electrical conductivity from June 2011 to September 2014. An artificial neural network based time series model was designed to filter out the effect of rainfall from the groundwater level data in the study area. Aquifer diffusivity and river resistance were estimated from the analytical solution of a one‐dimensional unit step response function by using the filtered groundwater level data. River resistance increased in response to groundwater level fluctuations. Cross‐correlation analyses between the groundwater and the river water showed that the lag time increased during the observation period for both the water level and the electrical conductivity while the cross‐correlation function declined for the same period. The results indicated that a constant river stage maintained at the river barrage can weaken the hydrologic stress and reduce the exchange of material between the river and the adjacent aquifer because of the deposition of fine sediment on the river bottom and walls. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

A petrogenetic grid for eclogite and related facies under high-pressure metamorphism   总被引：12，自引：0，他引：12  

C. W. Oh  & J. G. Liou 《Island Arc》1998,7(1-2):36-51

The petrogenetic grid between the eclogite and other high-pressure/temperature (P/T) metamorphic facies in a basaltic system is constructed by considering barroisite as one of the important phases in high-P/T metamorphism and by using previous petrological data combined with Schreinemakers' analysis and slope calculation. In the constructed petrogenetic grid, the eclogite facies is bounded by the blueschist and epidote–amphibolite facies with negative-slope reactions at lower temperatures (450–550 °C) and by the epidote–amphibolite, amphibolite and granulite facies with positive-slope reactions at higher temperatures (> 550–600 °C). The eclogite facies does not contact the greenschist facies, and the lowest P condition for the eclogite facies exists at the boundary between the eclogite and epidote–amphibolite facies. The temperature range of the epidote–amphibolite facies increases with increasing pressure until 8–11 kbar and then decreases up to 13–15 kbar. Compared to boundaries of other facies, boundaries of the eclogite facies may have wider P–T ranges. The boundary between the blueschist and eclogite facies occurs over a large temperature range from 450 to 620 ± 30 °C, and the transitions between the eclogite and amphibolite or high-pressure granulite facies occur over a pressure range in excess of 6–10 kbar.  相似文献   

Linear wave reflection by trench with various shapes     

Tae-Hwa Jung  Kyung-Duck Suh  Seung Oh Lee  Yong-Sik Cho 《Ocean Engineering》2008,35(11-12):1226-1234

Two types of analytical solutions for waves propagating over an asymmetric trench are derived. One is a long-wave solution and the other is a mild-slope solution, which is applicable to deeper water. The water depth inside the trench varies in proportion to a power of the distance from the center of the trench (which is the deepest water depth point and the origin of x-coordinate in this study). The mild-slope equation is transformed into a second-order ordinary differential equation with variable coefficients based on the longwave assumption [Hunt's, 1979. Direct solution of wave dispersion equation. Journal of Waterway, Port, Coast. and Ocean Engineering 105, 457–459] as approximate solution for wave dispersion. The analytical solutions are then obtained by using the power series technique. The analytical solutions are compared with the numerical solution of the hyperbolic mild-slope equations. After obtaining the analytical solutions under various conditions, the results are analyzed.  相似文献   

Variability of SeaWiFs chlorophyll-a in the southwest Atlantic sector of the Southern Ocean: Strong topographic effects and weak seasonality     

Jisoo Park  Im-Sang Oh  Hyun-Cheol Kim  Sinjae Yoo 《Deep Sea Research Part I: Oceanographic Research Papers》2010,57(4):604-620

This study examined 11-year (1997–2008) weekly and monthly time series of satellite-observed ocean color to understand the dominant temporal and spatial patterns of chlorophyll-a in the southwest Atlantic sector of the Southern Ocean. Using empirical orthogonal function analysis and k-means classification, we classified the study area into eight regions, which were in good accordance with the oceanographic and topographic features. Examination of the chlorophyll-a time series in each region revealed that contrary to our expectation, regular seasonal phytoplankton blooms were observed only in a limited area. Of the eight regions, only two showed typical seasonal blooms, and one showed weak seasonality, whereas other regions exhibited irregular seasonal blooms of variable duration. We attribute the absence of regularity in seasonal blooms to relatively shallow winter mixing, which would prevent entrainment of limiting micronutrients such as iron and silicate. In the southwest Atlantic sector of the Southern Ocean, topographic effects and sea ice may be the most important factors controlling primary productivity. In the South Georgia region, chlorophyll-a showed a significant correlation with geostrophic current velocity, indicating that topographic effects depend on the interaction of current strength and topographic structure. Interannual variability of the surface chlorophyll in some regions also revealed longer periodicity (～6 years). The periodicity seemed to be related to El Niño–Southern Oscillation and to sea-ice dynamics influenced by the Antarctic Circumpolar Current.  相似文献   

Comparing resident and tourist preferences for public beach access and related amenities     

Chi-Ok Oh  Jason Draper  Anthony W. Dixon 《Ocean & Coastal Management》2010,53(5-6):245-251

As coastal destinations continue to grow, due to tourism and residential expansion, the demand for public beach access and related amenities will also increase. The issue confronting management agencies responsible for providing and maintaining public beach access and related amenities is the varying needs and preferences of both residents and tourists of coastal destinations. The purpose of this paper is to provide comprehensive information about coastal recreational needs of residents and tourists with regards to public beach access and associated amenities using the stated preference choice method. Overall, the results indicate tourists were more interested in additional public beach access points and commercial development, while residents supported beach rules and regulations but opposed high levels of crowding and noise. Implications of these results for management agencies include the utilization of parking fees to subsidize additional public beach access points, identifying appropriate types and levels of commercial development that moderate the use of coastal resources by tourists and day-trip users, and implementing beach rules and regulations that reduce the potential for conflict between user groups. Providing management agencies with comprehensive information of the preferences of different beach user groups can assist in the development of more effective policies and management programs.  相似文献   

Hydraulic Fracturing In Situ Stress Estimations in a Potential Geothermal Site,Seokmo Island,South Korea   总被引：1，自引：0，他引：1  

Chandong Chang  Yeonguk Jo  Yangkyun Oh  Tae Jong Lee  Kwang-Yeom Kim 《Rock Mechanics and Rock Engineering》2014,47(5):1793-1808

We conducted hydraulic fracturing (HF) in situ stress measurements in Seokmo Island, South Korea, to understand the stress state necessary to characterize a potential geothermal reservoir. The minimum horizontal principal stress was determined from shut-in pressures. In order to calculate the maximum horizontal principal stress (S _Hmax) using the classical Hubbert–Willis equation, we carried out hollow cylinder tensile strength tests and Brazilian tests in recovered cores at depths of HF tests. Both tests show a strong pressure rate dependency in tensile strengths, from which we derived a general empirical equation that can be used to convert laboratory determined tensile strength to that suitable for in situ. The determined stress regime (reverse-faulting) and S _Hmax direction (ENE–WSW) at depths below ~300 m agrees with the first order tectonic stress. However the stress direction above ~300 m (NE–SW) appears to be interfered by topography effect due to a nearby ridge. The state of stress in Seokmo Island is in frictional equilibrium constrained by optimally oriented natural fractures and faults. However, a severe fluctuation in determined S _Hmax values suggests that natural fractures with different frictional coefficients seem to control stress condition quite locally, such that S _Hmax is relatively low at depths where natural fractures with low frictional coefficients are abundant, while S _Hmax is relatively high at depths where natural fractures with low frictional coefficients are scarce.  相似文献   

Influence of rain infiltration on the stability of compacted soil slopes   总被引：1，自引：0，他引：1  

Won Taek Oh  Sai K. Vanapalli 《Computers and Geotechnics》2010

Stability analyses for a homogeneous compacted embankment were undertaken considering infiltration of water into the embankment. The analyses include several different practical scenarios: (i) saturated condition, (ii) ponding (or runoff) along with saturated condition, (iii) short term analysis for unsaturated conditions, and (iv) long term analysis for unsaturated conditions. The appropriate shear strength parameters of the compacted soil required for analyzing different practical scenarios were determined using conventional and modified triaxial shear apparatus. The results of the study show that typically shallow circular failures above water front occur due to infiltration rather than the conventional infinite slope type failures.  相似文献   

Application of nonylphenol and coprostanol to identification of industrial and fecal pollution in Korea     

Li D  Shim WJ  Dong M  Oh SH 《Marine pollution bulletin》2007,54(1):101-107

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