Self-centering seismic retrofit scheme for reinforced concrete frame structures: SDOF system study   总被引：1，自引：1，他引：0  

Yunfeng Zhang  Xiaobin Hu 《地震工程与工程振动(英文版)》2010,9(2):271-283

This paper presents the results of a parametric study of self-centering seismic retrofit schemes for reinforced concrete (RC) frame buildings. The self-centering retrofit system features flag-shaped hysteresis and minimal residual deformation. For comparison purpose,an alternate seismic retrofit scheme that uses a bilinear-hysteresis retrofit system such as buckling-restrained braces (BRB) is also considered in this paper. The parametric study was carried out in a single-degree-of-freedom (SDOF) system framework since a multi-story building structure may be idealized as an equivalent SDOF system and investigation of the performance of this equivalent SDOF system can provide insight into the seismic response of the multi-story building. A peak-oriented hysteresis model which can consider the strength and stiffness degradation is used to describe the hysteretic behavior of RC structures. The parametric study involves two key parameters -the strength ratio and elastic stiffness ratio between the seismic retrofit system and the original RC frame. An ensemble of 172 earthquake ground motion records scaled to the design basis earthquake in California with a probability of exceedance of 10% in 50 years was constructed for the simulation-based parametric study. The effectiveness of the two seismic retrofit schemes considered in this study is evaluated in terms of peak displacement ratio,peak acceleration ratio,energy dissipation demand ratio and residual displacement ratio between the SDOF systems with and without retrofit. It is found from this parametric study that RC structures retrofitted with the self-centering retrofit scheme (SCRS) can achieve a seismic performance level comparable to the bilinear-hysteresis retrofit scheme (BHRS) in terms of peak displacement and energy dissipation demand ratio while having negligible residual displacement after earthquake.  相似文献   

基于PS-InSAR的输电塔结构及沿线地质监测技术     

郝飞  雷鹏  李想  苗壮  陈鹏  闫云峰  李中为  翟宇峰 《地理信息世界》2022,29(1):88-92

我国电力建设发展迅速,电力输送设施建设通常会跨越恶劣地质条件区域,这些区域易发生地质灾害,从而引起输电铁塔基础结构产生形变,严重威胁高压输电线路的运行安全.本文使用合成孔径雷达影像,应用永久散射体差分干涉测量(PS-InSAR)技术对高压输电塔结构及其沿线地表进行形变监测.使用相干系数阈值法来确定研究区域的永久散射体点...  相似文献   

雅鲁藏布江南带白垩纪地层划分及特征          下载免费PDF全文

张计东  范永贵  刘思林  马超  李先  廖云峰  刘洪章 《中国地质调查》2016,3(4):19-28

通过1∶25万区域地质调查,在藏南普兰县拉昂错—萨嘎县旦嘎东雅鲁藏布江结合带南带修康群中发现了大量放射虫化石,通过对该区沉积地层的详细调查,结合放射虫化石对原划修康群进行了充分解体,新厘定出侏罗系至始新统7个组级岩石地层单位,其中白垩系划分为折巴组与桑单林组。折巴组以杂色硅质岩、泥岩和页岩为主,夹砂岩、玄武岩等,与上覆上侏罗统旦嘎组和下伏下白垩统桑单林组呈整合接触关系,含丰富的早白垩世放射虫化石; 桑单林组以杂色石英砂岩、砂岩、泥岩、页岩及硅质岩为主,夹玄武岩等,整合于下白垩统折巴组与古近系蹬岗组之间,含丰富的晚白垩世放射虫与有孔虫化石。白垩系折巴组与桑单林组的建立与研究,丰富和完善了中生代特提斯洋盆区(雅鲁藏布江南带地层分区)的岩石地层沉积序列,提高了地层的研究水平,为研究该区沉积古地理环境和大地构造演化提供了新的基础资料。  相似文献   

基于Coons曲面与约束三角网的区域地质调查三维建模方法     

周文辉  郭甲腾  栗云峰  吴立新  李超岭 《地球信息科学学报》2016,18(6):734-741

目前基于野外地质调查数据自动、快速地建立区域三维地质体模型是中国全面开展三维数字地质填图的迫切需求。本文基于产状、地质界线与路线剖面等野外区域地质调查要素,提出了一种二维平面地质图及路线剖面图向三维地质体模型的快速转换方法。该方法针对无剖面约束及含剖面约束2种情形,通过地质界线区域分割、多段线仿射变换等空间几何变换处理,推估出剖面线约束的地下地质界线,基于Coons曲面构建出地质体的侧面模型;然后,通过约束三角网算法构建地质体的顶、底面模型,最终建立拓扑一致的区域地质体三维模型。基于此方法,对中国1:2.5万区域地质调查试点区域进行了区域三维地质建模实践,实现了火山口、地层、岩体、断层等典型地质构造的快速三维重建。  相似文献   

Potential promoted productivity and spatial patterns of medium- and low-yield cropland land in China   总被引：2，自引：1，他引：1  

Huimin Yan  Yongzan Ji  Jiyuan Liu  Fang Liu  Yunfeng Hu  Wenhui Kuang 《地理学报(英文版)》2016,26(3):259-271

With a continuously increasing population and better food consumption levels, improving the efficiency of arable land use and increasing its productivity have become fundamental strategies to meet the growing food security needs in China. A spatial distribution map of medium- and low-yield cropland is necessary to implement plans for cropland improvement. In this study, we developed a new method to identify high-, medium-, and low-yield cropland from Moderate Resolution Imaging Spectroradiometer (MODIS) data at a spatial resolution of 500 m. The method could be used to reflect the regional heterogeneity of cropland productivity because the classification standard was based on the regionalization of cropping systems in China. The results showed that the proportion of high-, medium-, and low-yield cropland in China was 21%, 39%, and 40%, respectively. About 75% of the low-yield cropland was located in hilly and mountainous areas, and about 53% of the high-yield cropland was located in plain areas. The five provinces with the largest area of high-yield cropland were all located in the Huang-Huai-Hai region, and the area amounted to 42% of the national high-yield cropland area. Meanwhile, the proportion of high-yield cropland was lower than 15% in Heilongjiang, Sichuan, and Inner Mongolia, which had the largest area allocated to cropland in China. If all the medium-yield cropland could be improved to the productive level of high-yield cropland and the low-yield cropland could be improved to the level of medium-yield cropland, the total productivity of the land would increase 19% and 24%, respectively.  相似文献   

Strategic transformation of regionalization for the agricultural comprehensive development: The example of Ningxia Hui Autonomous Region in China     

Wenjiao Shi  Yunfeng Hu  Xiaoli Shi  Zong Wang  Huimin Yan  Ziwei Xu  Bo Ren  Wenhui Kuang  Xinliang Xu  Weiming Cheng  Yan Chen  Dongbo Wu 《地理学报(英文版)》2016,26(12):1675-1688

Strategic transformation of regionalization for agricultural comprehensive development (ACD) was presented by the Ministry of Finance of the People’s Republic of China (MOF) in 2014. The regionalization is the premise and basis of the sustainable development and improved competitiveness for agriculture. Based on the environmental resources related to agriculture, such as cropland, climate, water resources, terrain, geomorphology, patterns of the ACD projects, distribution of ecological planning, etc., we devised 13 indices using the geographic comprehensive regionalization method. The indices took into account a combination of dynamic and static, qualitative and quantitative, as well as agricultural and ecological factors. The strategic transformation of regionalization for the ACD in Ningxia Hui Autonomous Region of China was performed; seven types were included: prioritized regions, prioritized and restricted regions, protected regions, protected and restricted regions, restricted and prioritized regions, restricted and protected regions, and restricted regions. A further 24 subtypes were used based on locations and ecological zones. The regionalization results showed that prioritized regions were mainly in northern Ningxia, the most suitable area for agriculture. The protected and restricted regions were in central and southern Ningxia. In the central part, drought was the limiting factor for agriculture, and water conservation projects there should be supported. The ecological environment is fragile in southern Ningxia, so there is a need for ecologically sound agriculture to be developed in this region. Such regionalization could achieve two goals, namely agricultural conservation and eco-environmental protection. It was performed following the requirement for scientific regionalization to include three types of regions (prioritized regions, protected regions, and restricted regions), and was applied at the township scale in a provincial or autonomous region for the first time. The results provide both guidance for the strategic transformation of the ACD in Ningxia, and a reference for similar work in other provinces.  相似文献   

Seismic analysis of diagrid structural frames with shear-link fuse devices     

Nasim S. Moghaddasi B.  Yunfeng Zhang 《地震工程与工程振动(英文版)》2013,12(3):463-472

This paper presents a new concept for enhancing the seismic ductility and damping capacity of diagrid structural frames by using shear-link fuse devices and its seismic performance is assessed through nonlinear static and dynamic analysis.The architectural elegancy of the diagrid structure attributed to its triangular leaning member configuration and high structural redundancy make this system a desirable choice for tall building design.However,forming a stable energy dissipation mechanism in diagrid framing remains to be investigated to expand its use in regions with high seismicity.To address this issue,a diagrid framing design is proposed here which provides a competitive design option in highly seismic regions through its increased ductility and improved energy dissipation capacity provided by replaceable shear links interconnecting the diagonal members at their ends.The structural characteristics and seismic behavior(capacity,stiffness,energy dissipation,ductility) of the diagrid structural frame are demonstrated with a 21-story building diagrid frame subjected to nonlinear static and dynamic analysis.The findings from the nonlinear time history analysis verify that satisfactory seismic performance can be achieved by the proposed diagrid frame subjected to design basis earthquakes in California.In particular,one appealing feature of the proposed diagrid building is its reduced residual displacement after strong earthquakes.  相似文献   

GRACE重力卫星在陆地水储量变化监测中的应用     

范云峰 《全球定位系统》2013,(5):83-86,89

介绍了GRACE重力卫星,并对GRACE重力卫星数据在陆地水储量变化中的应用现状进行分析,总结了GRACE重力卫星数据在陆地水储量变化检测中的数据获取、计算方法和精度分析,以及Grace数据在不同区域尺度陆地水储量变化估算中的应用情况,最后,指出GRACE在水储量应用中的不足和未来的研究方向。  相似文献   

Nontectonic signals in reprocessed continuous GPS position time series of CMONOC     

Yunfeng Tian 《地球空间信息科学学报》2013,16(3):207-215

The nearly nine-year continuous GPS data collected since 1 March 1999 from the Crustal Motion Observation Network of China (CMONOC) were consistently analyzed. Most of the nonlinear movements in the cumulative position time series produced by CMONOC data center disappeared; and more accurate vertical terms and tectonic signals were extracted. Displacements caused by atmospheric pressure loading, nontidal ocean loading, soil moisture mass loading, and snow cover mass loading using the National Centers for Environmental Prediction (NCEP) Reanalysis I/II models and Estimation of the Circulation and Climate of the Ocean (ECCO) data can explain most of the vertical annual terms at many stations, while only parts can be explained at Lhasa and southern coastal sites, indicating that there are some deformation mechanisms that are still unknown or not modeled accurately. The remarkable differences in vertical position time series for short-baseline sites reveal that GPS stations can be greatly affected by local factors; and attention should be paid when explaining observed GPS velocity vectors.  相似文献   

渤海海域黄河口凹陷新近系多油水系统油藏成因分析          下载免费PDF全文

胡光义  杨希濮  古莉  范廷恩  王晖  汪珍宇  高云峰 《地学前缘》2012,19(2):95-101

为明确同类油田的开发调整方向和潜力目标,以滚动勘探开发为目的,以A油田为例,探讨了黄河口凹陷中央构造脊北端新近系多油水系统油藏成因。储层与油源断层的有效配置是控制该类油气聚集的关键因素。基于已开发油田井震一体化精细地层对比和储层展布研究,细化了储层空间展布,并结合油源断层特征剖析,系统分析了储-断耦合对油气分布的控制作用。首先,油源断裂垂向活动强弱的差异与储层的匹配控制着油气垂向上主要聚集层位;其次,断裂平面发育程度的差异与储层展布的耦合控制着油气在平面上的分布;再次,储-断接触关系影响着油气的富集和赋存规律。  相似文献