Stiffened steel box columns. Part 1: Cyclic behaviour     

Hanbin Ge  Shengbin Gao  Tsutomu Usami 《地震工程与结构动力学》2000,29(11):1691-1706

This paper aims to study the cyclic inelastic behaviour of stiffened steel box columns failed by local and overall interaction instability under a constant compressive axial force and cyclic lateral loading. Such columns find broad application in steel bridge piers. The columns are of box sections with longitudinal stiffeners. In the analysis, a modified two‐surface plasticity model developed at Nagoya University is employed to model material non‐linearity. For comparison, analyses using classical isotropic‐ and kinematic‐hardening models are also carried out. Hysteretic curves and buckling modes obtained from analysis using the two‐surface model and classical models are compared with experimental results. Moreover, the progression of deformation from occurrence of local buckling to structural failure is discussed in detail. The comparisons show that the use of an accurate plasticity model is quite important in the prediction of both the cyclic inelastic behaviour and failure characteristic of steel box columns failed by coupled local and overall instability. It is found that the modified two‐surface model is a satisfactory model in predicting the cyclic hysteretic behaviour of both the thin‐ and thick‐walled steel box columns. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

汶川地震庙子坪特大桥主桥箱梁开裂震害分析          下载免费PDF全文

童磊  王东升  王荣霞 《世界地震工程》2020,(3):161-171

2008年汶川地震中庙子坪特大桥主桥箱梁开裂严重,并在两个端部（过渡墩处）有较大的横向残余位移。为深入了解主梁开裂震害原因,选取桥址附近台站实测的八条强震动记录及常用El Centro等波作为输入,考虑箱梁施工过程及初始应力影响,通过时程分析进行数值模拟并与实际震害比较。结果表明:不同地震波输入下得到的箱梁高应力区与实际开裂区吻合较好,预示箱梁开裂震害不属于偶然现象。箱梁在主墩处、边跨和中跨合龙段区域处的顶板,边跨1/6~1/2及中跨1/4~3/4区域处的腹板,边跨和中跨合龙段及其相邻2~3个节段处的底板,在地震中易出现高拉或压应力区。地震过程中估计纵向预应力筋应力增加接近100MPa,横桥向挡块破坏降低了跨中箱梁的拉和压应力,对箱梁开裂震害有一定减轻作用。  相似文献   

地震环境下钢筋混凝土箱梁复合受力特性分析   总被引：1，自引：1，他引：0       下载免费PDF全文

刘觅  高亮 《地震工程学报》2018,40(4):665-670

利用传统有限元分析法对地震环境下钢筋混凝土箱梁复合受力特性分析时,采用专家经验进行配筋,存在较强的主观意识,导致获取的复合受力特性分析结果存在偏差。根据以往的实验研究参数结合国家对混凝土桥梁参数的限制条件,构建地震环境下钢筋混凝土箱梁复合受力实验模型。设定实验模型尺寸,根据模型尺寸选择模型材料,采用圆钢与角钢搭建跨梁连续支座,融合反力架与千斤顶设计实验加载方案;根据方案中得出的配筋计算结果,获取地震环境下钢筋连续箱梁复合受力实验模型的科学配筋方案。实验结果表明,该实验模型可对地震环境下钢筋混凝土箱梁复合受力特性进行全面、准确分析。  相似文献   

Cyclic tests of steel plate shear walls using box‐shape vertical boundary elements with or without infill concrete          下载免费PDF全文

Chao‐Hsien Li  Keh‐Chyuan Tsai  Hsuan‐Yu Huang  Ching‐Yi Tsai 《地震工程与结构动力学》2017,46(14):2537-2564

The steel plate shear wall (SPSW) is an effective lateral force resisting system in which unstiffened steel infill plates are connected to the horizontal and vertical boundary elements (VBEs) on all sides of the plates. The boundary elements must be designed to resist the tension field force of the infill panels. When the VBEs are made from a steel box section, the flange of each box VBE connected with the infill panels can be pulled out‐of‐plane by significant panel forces, called pull‐out action. This study investigates capacity design methods for box VBEs in SPSWs. Simplified fixed beam and portal frame models aim to estimate the pull‐out responses of the flange of the box sections with and without infill concrete, respectively. In this study, cyclic tests of three full‐scale two‐story SPSWs using box VBEs with or without the infill concrete are conducted. Inelastic pushover analyses of the finite element models are conducted. The tests and analytical results confirm that the proposed design methods, which aimed to prevent the full yield of the flange under the pull‐out action, are applicable. Furthermore, the test and analytical results suggest that the initial yielding of the flange of box VBEs under the collective effects of the pull‐out action on the flange, the gravity load, and the sway action on the SPSW represents a local yielding. A strict prohibition of the initial yielding on the flange under the aforementioned collective effects is not recommended for pursuing a cost‐effective design. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

锆石环氧树脂靶表面形貌特征及对LA-ICP-MS分析影响研究     

胡志中  王坤阳  晏雄  杨波  杜谷 《岩矿测试》2020,39(6):804-815

激光剥蚀电感耦合等离子体质谱（LA-ICP-MS）是目前锆石研究常用方法之一,该法普遍采用环氧树脂靶为载体,对锆石环氧树脂靶表面形貌及平整度影响进行研究,有助于评估其制作工艺以及LA-ICP-MS锆石分析的准确性。本次研究采用原子力显微镜（AFM）对锆石环氧树脂靶表面进行形貌分析,并通过分析和对比193nm激光不同剥蚀模式和不同剥蚀条件下的锆石表面形貌,研究锆石表面形貌及平整度对LA-ICP-MS锆石分析的影响;同时实验采用氩离子抛光技术对锆石环氧树脂靶进行二次抛光,并探讨该技术对锆石环氧树脂靶影响。实验结果表明本次靶中表面总体平整性较好但存在细微的不平,锆石表面存在程度较小（几至几十纳米的不等）的擦痕,锆石颗粒边缘与靶面存在高差和间隙;而通过研究后认为锆石表面细微的不平对于分析的影响小于能量密度、频率、移动速率等其他激光参数的影响,对分析准确性的影响较小。实验分析并对比了锆石和玻璃标准等不同基体的线扫描形貌,发现其剥蚀深度以及剥蚀形貌存在差异,相同剥蚀条件下线扫描剥蚀深度：NIST610 > CGSG系列 > 锆石91500。经氩离子二次抛光后锆石样品表面擦痕不明显,但可能会对锆石造成损伤等影响。本次研究认为锆石环氧树脂靶表面总体平整性较好,锆石表面细微的不平对分析准确性的影响较小,不同基体的线扫描形貌研究则为LA-ICP-MS锆石及其他分析提供了参考,而氩离子抛光技术对LA-ICP-MS分析的影响及应用还有待进一步的研究。  相似文献   

大跨斜拉桥悬臂端钢箱梁上监测点高程测量新方法     

赵政权  刘成龙  孙太山 《四川测绘》2010,(6):253-255

在斜拉桥的主梁施工中,需要高精度测量悬臂端钢箱梁的高程。随着悬臂的增长,桥面的晃动越来越大,水准仪读数的难度也越来越大,甚至读不出数据;同时由于梁面上施工设备的影响,测量的难度很大,时间也很长。本文提出采用Leica TCA2003全站仪测量高差和水准仪测量工作基点高程相结合的方法,测量钢箱梁上监测点的高程,通过理论分析和对比实验证明了该方法的可行性。  相似文献   

鹿山大桥移动模架施工测量技术     

崔亦芳  赵站杨 《北京测绘》2010,(3):51-53

鹿山大桥路线总长约2.422km,跨越约900m宽的富春江,水中和岸上引桥均采用预应力混凝土连续箱梁,跨径为31～50m,总长度为1018.1m,由两岸双幅25孔梁组成,主要采用移动模架进行施工。结合本桥的工程概况及特点,介绍了大桥的移动模架施工测量方法。  相似文献   

Sequestration of As and Mo in uranium mill precipitates (pH 1.5–9.2): An XAS study     

《Applied Geochemistry》2016

As- and Mo- bearing secondary mineral phases formed during the neutralization of uranium mill wastes require characterization. Previous studies indicate that arsenate and molybdate adsorbed to ferrihydrite are the dominant controls in the tailings materials. A lab-scale plant was employed to characterize secondary precipitates from a variety of ore blends. Through total elemental analysis of precipitates and As and Mo K-edge X-ray absorption spectroscopy, different ratios of contributing phases were determined for each pH stage (4.2, 6.5, and 9.2) of the neutralization process. Overall, arsenate adsorbed to ferrihydrite was the dominant As mineral phase regardless of pH or sample blend (53–77%), with fractional contribution from ferric arsenates, and adsorption to aluminum phases. Molybdate adsorbed to ferrihydrite was the dominant Mo mineral phase, with fractional contribution decreasing with increasing pH (100–69%). The characterization of these phases in the secondary precipitates provides further understanding of the contributing mineral species in tailing facilities.  相似文献   

Redox cycling of iron and manganese in sediments of the Kalix River estuary, Northern Sweden     

Anders Widerlund  Johan Ingri 《Aquatic Geochemistry》1996,2(2):185-201

Iron and manganese redox cycling in the sediment — water interface region in the Kalix River estuary was investigated by using sediment trap data, pore-water and solid-phase sediment data. Nondetrital phases (presumably reactive Fe and Mn oxides) form substantial fractions of the total settling flux of Fe and Mn (51% of Fe_total and 84% of Mn_total). A steady-state box model reveals that nondetrital Fe and Mn differ considerably in reactivity during post-depositional redox cycling in the sediment. The production rate of dissolved Mn (1.6 mmol m^–2 d^–1) exceeded the depositional flux of nondetrital Mn (0.27 mmol m^–2 d^–1) by a factor of about 6. In contrast, the production rate of upwardly diffusing pore-water Fe (0.77 mmol m^–2 d^–1) amounted to only 22% of the depositional flux of nondetrital Fe (3.5 mmol m^–2 d^–1). Upwardly diffusing pore-water Fe and Mn are effectively oxidized and trapped in the oxic surface layer of the sediment, resulting in negligible benthic effluxes of Fe and Mn. Consequently, the concentrations of nondetrital Fe and Mn in permanently deposited, anoxic sediment are similar to those in the settling material. Reactive Fe oxides appear to form a substantial fraction of this buried, non-detrital Fe. The in-situ oxidation rates of Fe and Mn are tentatively estimated to be 0.51 and 0.16–1.7 mol cm^–3 d^–1, respectively.  相似文献   

GIS空间数据库系统误差控制的黑箱方法   总被引：1，自引：0，他引：1  

史文中  刘文宝 《遥感学报》1998,2(3):199-203

ＧＩＳ建库数据中系统误差的控制是当前ＧＩＳ数据质量研究领域的重要方向之一。本文提出一种直接估计系统误差综合效应的黑箱方法,而传统的仿射变换将成为该法的特例。文中首先阐述黑箱方法的基本原理,然后根据多元统计学工具建立黑箱校正模型,最后给出模型辨识和参数辨识的具体方法。  相似文献