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131.
This paper presents general composed analytical models to predict the behavior of reinforced concrete (RC) bridge columns. The analytical models were developed in OpenSees to represent the common hysteretic behavior of RC bridge columns. The proposed composed models can accommodate flexure failure, flexure‐shear failure, and pure shear failure, which are observed in existing RC bridge piers. The accuracy of the models was verified using data from the static cyclic‐loading experiments of 16 single columns and one multi‐column bent and dynamical experiment from two pseudo‐dynamic tests. The results showed that the analytical models could simulate the nonlinear behavior until the post‐failure behavior, including the strength degradation, the buckling of the reinforcement, and the pinching effect. Therefore, a global view of the behavior of reinforcement concrete is prescribed as simply as possible from the academic perspective, and these models are expected to provide sufficient accuracy when applied in engineering practice. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
132.
Hyongki Lee C.K. Shum Yuchan Yi Alexander Braun Chung-Yen Kuo 《Journal of Geodynamics》2008,46(3-5):182
A new method to estimate the vertical crustal motion from satellite altimetry over land was developed. The method was tested around Hudson Bay, where the observed vertical motion is largely caused by the incomplete glacial isostatic adjustment (GIA) as a result of the Laurentide ice sheet deglaciation since the last glacial maximum (LGM). Decadal (1992–2003) TOPEX/POSEIDON radar altimetry data over land surfaces were used. The results presented here are improved compared to a previous study (Lee, H., Shum, C.K., Kuo, C.Y., Yi, Y., Braun, A., 2008. Application of TOPEX altimetry for solid Earth deformation studies. Terr. Atmos. Ocean. Sci. 19, 37–46. doi:10.3319/TAO.2008.19.1-2.37(SA).) which estimated vertical motion only over relatively flat land surfaces (standard deviation of the height variation <40 cm). In this study, we extended the concept of traditional 1-Hz (one-per-frame) radar altimeter ocean stackfiles to build 10-Hz (10-per-frame) land stackfiles over Hudson Bay land regions, and succeeded in obtaining vertical motion estimates over much rougher surfaces (standard deviation of the height variation <2 m). 90-m C-band Shuttle Radar Topography Mission (SRTM) Digital Elevation Model (DEM) is used as a reference surface to select an optimal waveform retracker, to correct surface gradient errors, and to calculate land surface anomalies. Here, we developed an alternative retracker, called the modified threshold retracker, resulting in decadal vertical motion time series over a 1500 km by 1000 km region covering northern Ontario, northeastern Manitoba, and the Great Lakes region which is at the margin of the former Laurentide ice sheet. The average of the estimated uncertainties for the vertical motion is 2.9 mm/year which is comparable to 2.1 mm/year of recent GPS solutions. The estimated vertical motion is compared with other geodetic observations from GPS, tide gauge/altimetry, GRACE, and several GIA models. The data agree best with the laterally varying 3D GIA model, RF3S20 (β = 0.4) whereas the combination of land altimetry solution with other measurements match best with the models RF3S20 (β = 0.0) or RF3S20 (β = 0.2) in terms of mean and standard deviation of the differences. It is anticipated that this innovative technique could potentially be used to provide additional constraints for GIA model improvement, and be applied to other geodynamics studies. 相似文献
133.
Sohan Lal A. Joshi Sandeep Monu Tomer Parveen Kumar Chun-Hsiang Kuo Che-Min Lin Kuo-Liang Wen M. L. Sharma 《Acta Geophysica》2018,66(4):461-477
On 25th April, 2015 a hazardous earthquake of moment magnitude 7.9 occurred in Nepal. Accelerographs were used to record the Nepal earthquake which is installed in the Kumaon region in the Himalayan state of Uttrakhand. The distance of the recorded stations in the Kumaon region from the epicenter of the earthquake is about 420–515 km. Modified semi-empirical technique of modeling finite faults has been used in this paper to simulate strong earthquake at these stations. Source parameters of the Nepal aftershock have been also calculated using the Brune model in the present study which are used in the modeling of the Nepal main shock. The obtained value of the seismic moment and stress drop is 8.26 × 1025 dyn cm and 10.48 bar, respectively, for the aftershock from the Brune model .The simulated earthquake time series were compared with the observed records of the earthquake. The comparison of full waveform and its response spectra has been made to finalize the rupture parameters and its location. The rupture of the earthquake was propagated in the NE–SW direction from the hypocenter with the rupture velocity 3.0 km/s from a distance of 80 km from Kathmandu in NW direction at a depth of 12 km as per compared results. 相似文献
134.
135.
浙江渔场修复振兴暨"一打三整治"(依法打击涉渔"三无"船舶和违反伏休规定等违法生产经营行为,全面开展渔船"船证不符"整治、禁用渔具整治和污染海洋环境行为整治)专项执法行动实施以来,已取得显著成效,但也存在一些问题。文章基于调研所获资料,综合分析涉渔"三无"船舶回潮、部分伏休政策实施困难以及渔船"船证不符"、禁用渔具和海洋环境污染整治不彻底等问题及其原因,提出建立长效机制、加大整治力度和建立省内外联动机制的对策建议,为浙江省海洋生态修复、渔业资源保护和渔业可持续发展的相关决策提供参考。 相似文献
136.
在全球增暖及海平面上升背景下,风暴潮极端事件愈加严重,修筑海防工程是沿海地区应对和适应风暴潮灾害的主要工程性措施。以珠江三角洲为研究区,基于风暴潮历史灾害数据,分析了风暴潮增水与社会经济损失的关联性;提出了定量评价工程性适应风暴潮灾害的经济损益理论关系模型;推算了未来极端事件情景下,珠江三角洲海防工程建设的适应效果。结果表明,珠江三角洲地区风暴潮灾害的灾损率与增水呈显著正相关。海防工程建设高度在1.69~11.85 m内处于收益状态,其中5.22 m时收益最大。基于2030年、2050年以及2100年海平面上升叠加风暴潮情景,将海防工程设防标准定为应对2100年20年一遇风暴潮时的收益最大,标准定为应对2100年100年一遇风暴潮时收益最小。 相似文献
137.
Ching-Yuang Huang Ying-Hwa Kuo Shu-Ya Chen Chuen-Tsyr Terng Fang-Ching Chien Pay-Liam Lin Mien-Tze Kueh Shu-Hua Chen Ming-Jen Yang Chieh-Ju Wang Anisetty S. K. A. V. Prasad Rao 《GPS Solutions》2010,14(1):35-49
The impact of GPS radio occultation (RO) data assimilation on severe weather predictions in East Asia is introduced and reviewed. Both the local observation operator that assimilates the retrieved refractivity as local point measurement, and the nonlocal observation operator that assimilates the integrated retrieved refractivity along a straight raypath have been utilized in WRF 3DVAR to improve the initial analysis of the model. A general evaluation of the impact of these approaches on Asian regional analysis and daily prediction is provided in this paper. In general, the GPS RO data assimilation may improve prediction of severe weather such as typhoons and Mei-yu systems when COSMIC data were available, ranging from several points in 2006 to a maximum of about 60 in 2007 and 2008 in this region. Based on a number of experiments, regional model predictions at 5 km resolution were not significantly influenced by different observation operators, although the nonlocal observation operator sometimes results in slightly better track forecast. These positive impacts are seen not only in typhoon track prediction but also in prediction of local heavy rainfall associated with severe weather over Taiwan. The impact of 56 GPS RO soundings on track prediction of Cyclone Gonu (2007) over the Indian Ocean is also appealing when compared to other tracks assimilated with different observations. From a successive evaluation of skill scores for real-time forecasts on Mei-yu frontal systems operationally conducted over a longer period and predictions of six typhoons in 2008, assimilation of GPS RO data appears to have some positive impact on regional weather predictions, on top of existent assimilation with all other observations. 相似文献
138.
Seismic monitoring of western Pacific typhoons 总被引:2,自引:0,他引:2
Wu-Cheng Chi Wan-Jou Chen Ban-Yuan Kuo David Dolenc 《Marine Geophysical Researches》2010,31(4):239-251
Typhoons inflict large damage to societies, but are usually difficult to monitor in close proximity in real-time without expensive
instruments. Here we study the possibility of using seismic waveforms on the seafloor and on land to monitor the turning of
a far away or approaching typhoon. Up to 67% of the typhoons making landfall in Taiwan come from the eastern shore, so that
we deployed broadband ocean-bottom seismometers (OBSs) offshore eastern Taiwan in 2006 to study ground motion in close proximity
to a typhoon. Typhoons generate ocean waves, which generate pressure signals in the water column before being transmitted
to the seafloor as seismic waves and recorded by the OBSs. The ground motions on the seafloor correlate with locally increased
(ocean) wave heights and wave periods, suggesting that the ground motions are mostly induced by in situ or nearby pressure
fields, as shown by coherence function analyses. When a typhoon turns and changes wave-wave interaction near the source region,
a new set of en echelon patterns develops which can be observed by OBSs and land stations. Similar features occur when a typhoon crosses a landmass
and re-enters the ocean. The energy level ratio between the single-frequency and double-frequency microseisms also changes
abruptly when the typhoon turns. These features can potentially help near real-time early warning with little cost to complement
other conventional typhoon early warning methods. 相似文献
139.
A higher-order non-hydrostatic σ model is developed to simulate non-linear refraction–diffraction of water waves. To capture non-linear (or steep) waves, a 4th-order spatial discretization is utilized to approximate the large horizontal pressure gradient. A higher-order top-layer pressure treatment is further implemented to resolve wave propagation. The model's characteristics including linear wave dispersion and non-linearity are carefully examined. The accuracy of the present model using only two vertical layers is validated by laboratory data and the available results predicted by the non-linear Schrödinger equation, Boussinesq-type equations, the non-linear mild slope equation, and the Laplace equation. Features of harmonic generation as well as the influences of dispersion and non-linearity on wave energy transfer processes are discussed. 相似文献
140.
A joint surface roughness/volumetric perturbation scattering theory is utilized to characterize bubbly ocean surface reverberation. Backscattering strength predictions are shown to be consistent with observed reverberation phenomena such as critical wind speeds, excess levels due to volumetric scattering, and saturation 相似文献