基于位移设计的钢筋混凝土桥墩抗震性能试验研究(Ⅰ):拟静力试验

通过拟静力试验研究了基于位移设计钢筋混凝土桥墩的抗震性能。利用基于位移抗震设计方法和桥梁抗震规范方法设计了各2根和1根1：2．5比例钢筋混凝土桥墩试件,对低周反复荷载作用下试件试验破坏形态、承载力、位移延性、滞回耗能、刚度退化等方面进行了比较分析,可以认为基于位移设计的钢筋混凝土桥墩能够达到预期的延性抗震要求,并且在相对耗能能力（与理想弹塑性模型相比）、刚度退化性能方面与现行规范抗震设计方法设计的桥墩相当。试验表明建议的钢筋混凝土桥墩基于位移的抗震设计方法是实际可行的。     

基于位移设计的钢筋混凝土桥墩抗震性能试验研究(Ⅱ):振动台试验

通过模型振动台试验研究了基于位移设计的钢筋混凝土桥墩的抗震性能。以完成的拟静力试验中的桥墩试件为参考原型,利用基于位移抗震设计方法和现行桥梁抗震规范方法设计了4根1:2的钢筋混凝土桥墩试件并进行了模型振动台试验。对小震、中震和大震作用下桥墩试件的破坏形态、加速度和位移反应、位移延性系数和地震总输入能(耗能)等方面进行了比较分析。综合拟静力试验和振动台试验结果,可以认为基于位移设计的钢筋混凝土桥墩能够达到预期的延性抗震要求。     

钢管混凝土桥墩抗震性能试验研究

为研究钢管混凝土桥墩的抗震性能,对钢管混凝土桥墩和钢筋混凝土桥墩进行了拟静力对比试验研究。根据试件的破坏发展过程以及各试件的滞回曲线和骨架曲线,分析了其滞回性能、耗能能力、延性、强度退化及刚度退化等抗震性能。试验结果表明,钢管混凝土桥墩的抗震性能明显好于钢筋混凝土桥墩。在含钢率和轴力相同的情况下,钢管混凝土桥墩的滞回曲线比钢筋混凝土桥墩丰满得多,前者的耗能能力约为后者的4.46倍,钢管混凝土桥墩的延性大于钢筋混凝土桥墩;随着轴压比的增大,钢管混凝土桥墩延性有所下降,强度退化加快,但对其刚度退化的影响不大。     

局部锈蚀矩形RC墩重度震损后加固试验研究

为探究局部锈蚀矩形截面钢筋混凝土（RC）桥墩重度震损加固后的抗震性能,本文对拟静力破坏后的6个矩形截面RC桥墩试件进行扩大截面加固。通过加载试验,对加固桥墩试件从破坏形态、滞回特性、水平承载力、位移延性、侧向刚度以及耗能等方面进行了系统分析。结果表明:相比于普通箍筋,横向施加预应力的改进扩大截面加固方式对破坏后桥墩试件的抗震性能修复成效更佳;在同等位移幅值下,锈蚀率不断增大,桥墩试件抗震性能呈现逐渐降低的趋势;钢筋锈蚀位置上移,加固后桥墩试件的抗震性能提升;轴压比加大,加固后桥墩试件承载力和侧向刚度增大,但延性降低。     

边缘约束构件对钢筋混凝土剪力墙抗震性能的影响

钢筋混凝土剪力墙是高层建筑中的主要抗侧力构件,边缘约束情况是影响剪力墙抗震性能的一个重要因素。为研究边缘约束构件对钢筋混凝土剪力墙抗震性能的影响,本文进行了三片边缘约束情况不同的钢筋混凝土剪力墙的低周反复试验,并对试验结果进行了分析,分析内容包括：破坏形态、水平承载力、位移延性系数、刚度退化、抗震耗能能力等方面。研究结果表明,合理地设置边缘约束能够扩大塑性破坏区域,提高试件的水平承载力,改善其抗震耗能性能。研究进一步发现,边缘纵筋配筋率在提高试件的水平承载力,改善其抗震耗能性能和刚度退化程度方面影响显著,而边缘配箍率对抗震性能的贡献在本次试验分析中表现得并不明显。     

不同加载角度与轴压比下RC短柱抗震性能试验研究

进行了加载角度为0°、22.5°及45°的钢筋混凝土方形短柱试件在轴压比分别为0.2及0.6下的低周往复加载试验,从破坏形态、承载力、延性及耗能能力等方面对钢筋混凝土方形短柱的抗震性能进行了研究。结果表明:增大轴压比能有效提高RC方形短柱的承载能力、耗能能力和减缓试件的后期强度退化,但同时会加速其刚度退化;加载角度对试件的承载力及刚度退化基本上没有影响,但延性、耗能能力及强度退化率会随加载角度的增加而增大。     

低层装配式钢筋混凝土水平坐浆墙体抗震性能试验研究

为了研究低层装配式钢筋混凝土水平坐浆墙体的抗震性能,对3个不同剪跨比的低层装配式钢筋混凝土水平坐浆墙体进行了低周反复荷载试验。根据试验结果,分析了剪跨比对墙体的破坏形态、承载力、变形能力、刚度退化和耗能能力的影响。结果表明:随着剪跨比的减小,墙体的破坏形态由弯曲破坏转为剪切破坏;试件SW2和试件SW3的承载力相对于试件SW1分别提高68%和110%,延性分别降低21.8%和37.5%;试件SW1的耗能能力最好,刚度退化速度最缓慢;预制钢筋混凝土墙板与现浇边缘构件协同合作,连接处无竖向裂缝,墙体整体性较好,具有良好的抗震性能,可用于我国城镇建设中的低层住宅结构。     

钢筋混凝土空心桥墩的振动台试验研究

为研究空心桥墩的抗震性能及影响参数,对9个不同配筋率、配箍率和轴压比的试件进行振动台试验。研究了不同性能量化参数对破坏现象、加速度响应、动力放大系数、延性和耗能等的影响。结果表明:轴压比和配筋率较小时,裂缝开展较多且位置距墩底相对偏高。增大配筋率,加速度响应、动力放大系数和位移延性系数增大,耗能减小;轴压比的影响与配筋率相反。增大配箍率,加速度响应和动力放大系数减小,位移延性系数和试件耗能增大。可为矩形空心桥墩的抗震设计提供参考。     

两层两跨方钢管混凝土框架抗震性能试验研究

为了研究采用穿芯高强螺栓-端板节点的方钢管混凝土框架的抗震性能,对一榀两层两跨的方钢管混凝土柱-钢梁框架进行了竖向荷载和低周反复水平荷载作用下的抗震性能试验研究,观测了框架的破坏形态,得到了框架试件的荷载-位移滞回曲线、骨架曲线,分析了方钢管混凝土框架的破坏机制、滞回性能、延性、耗能能力、强度及刚度退化等力学性能。结果表明:框架试件基本实现了梁铰破坏机制,具有良好的变形性能和耗能能力,位移延性系数为5.86~6.42,等效黏滞阻尼系数达到0.454,均满足延性框架的抗震要求。框架试件的强度和刚度退化较为平缓,具有较强的抗侧移能力。     

纤维增强混凝土十字形柱中节点试验研究

本文通过对6个1/2缩尺的十字形柱中节点试件进行反复荷载试验,对比此类节点的破坏过程及破坏特点,分析滞回特征、位移延性、刚度退化、承载力、耗能能力,研究纤维对十字形柱中节点抗震性能的增强作用。试验研究表明:节点核心区使用纤维混凝土可以显著改善节点混凝土剥落状态、提高位移延性和承载力、减缓刚度退化。     

琼中地震台重力仪记录同震响应特征分析

2013年2月6-8日圣克鲁斯群岛发生6次强震,琼中地震台的重力仪记录都有同震响应出现。本文从重力仪记录的面波的延迟时间、最大变形幅度、同震持续时间3个方面研究了6次强震的同震响应特征。     

On the Mechanism of the Secular Tidal Acceleration of the Solid Inner Core and the Viscosity of the Liquid Core

As is known, the secular deceleration of the Earth's diurnal rotation is explained mainly by the tidal friction in the ocean. Below we consider this mechanism in some detail, taking into account also elastic deformations of the mantle under the action of ocean loading and the interaction between the tide-generating body, ocean tidal wave, liquid outer core, and solid inner core. It is shown that elastic displacements of the core-mantle boundary under the action of ocean loading are of about the same amplitude and phase as the elastic loading displacements of the Earth's outer surface. As a result, side by side with the mechanism of secular deceleration of diurnal rotation of the mantle, there are also (1) the opposite mechanism of secular acceleration of diurnal rotation of the outer liquid core and of the solid inner core and (2) the mechanism of excitation of differential rotation in the liquid core. Taking these effects into account, we compare theoretical and modern observed data on the eastward drift of the solid inner core. It is shown that the best agreement may be obtained if the turbulent viscosity of the liquid core is about 2 × 10 ³ Poise     

Comparison Between the Nutations of the Planet Mars and the Nutations of the Earth

The nutations of the planets Mars andEarth are investigated and compared. Alarge number of interior structureparameters are involved in the nutationcomputations. The comparison between the observations and the computationsprovides several constraints on these parmeters andtherefore allows a better understanding of the physics of the interior of theplanet. For the Earth, the high precision of the observations of the nutationshas led to a very good determination of interior properties of the planet. ForMars, observations of nutations are not yet available, and we review how theamplitude of the Martian nutations depends on the hypotheses consideredfor its interior. Although Mars is very similar to the Earth, its interior is not well known;for example, we don't knowif its core is liquid or solid. Only if the core is liquid,the Free Core Nutation (FCN) normal mode exists and can alter the nutationswhich are close to the resonance. From the observed geoids, it is known thatboth planets are not in hydrostatic equilibrium. The departure is larger forMars than for the Earth, and consequently, the implication of considering a convective mantle instead of a mantle in hydrostatic equilibrium described byClairaut's equation for the initial equilibrium state of the planet is largeron the Martian nutations than on the Earth nutations. The consequences of theuncertainty in the core dimensions are also examined and shown to be of a veryhigh influence for Mars if the core is liquid, due to the potential changes inthe FCN resonance. The influence of the presence of an inner core, which isknown to exist for the Earth, could be more important for Mars than for theEarth if the inner core is large. Due to the presence of Tharsis on Mars, thetriaxiality of this planet has, additionally, larger effects than on Earth.     

Contribution to the knowledge of the magmatic evolution by the study of the variation of the coefficient of viscosity

The determination of the coefficient of viscosity of eruptive products gives useful elements to the knowledge of possible variations of composition and physical conditions of the magmas.     

Evolution of the Source of the Active Region of the Sun

Geomagnetism and Aeronomy - The magnetic evolution of the active region of the Sun at the level of the photosphere has been studied. Magnetic synoptic maps of the 2007 Kitt Peak Observatory were...     

Pictorial Series of the Manifestations of the Dynamics of the Earth

Studia Geophysica et Geodaetica -     

动水压力对深水桥墩地震响应影响的研究综述

地震激励下处于深水中的桥墩和周围水体的相互作用将对桥梁结构的动力响应产生较大影响。首先对地震作用下水-桥墩的相互作用理论做了概括,给出了动水压力对桥墩的作用效应及各自的适用范围;对主要的三种考虑流固耦合效应的分析方法做了对比,探讨了地震作用下影响水-结构相互作用的主要因素,并对今后的研究提出了建议。     

On the solution of the reverse problem of geodesics with the help of the chord

Резюме Дается вывод формул для вычислений длины хорды, длины и азимутов нормаляных сечений и длины геодезической линии эллипсоида. Применяются тригонометрические функции данных величин и постоянные принятого ргфгргнц-эллипсоида, что является целесообразным при использовании вычислителQjных машин, особенно автоматов. Рабочие формулы рекомендуются в форме (8–11).

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Dedicated to Professor František Fiala on His 85th Birthday

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Address: Veveři 95, Brno.     

On the gravimetric undulations of the geoid and the deflections of the vertical

Summary The author mentions the aims of the World-wide gravity project he established in the Ohio State University in Columbus, in 1950. He outlines the practical procedure of the gravimetric computations of the undulationsN and the vertical deflection components and and emphasizes that only by the global international cooperation and additional gravity observations at sea carried out during the last decade it has been possible to gather to Columbus the needed gravity material. Since there exist still large gravimetrically unsurveyed areas it is of vital significance to study what gravity anomalies are best to be used for these regions. The given figures concerning the accuracy of theN, and , estimated theoretically and obtained in practice, indicate that in the gravimetrically well surveyed parts of the world like in Europe and the United States we can get gravimetrically on basis of existing gravity material theN-values with accuracy of about 5–10 meters, and and with the accuracy of about 1. The geoid undulationsN are already computed in Columbus for more than 6000 points of the northern hemisphere. The sample maps show the interesting geoid of Europe and vicinity between the latitudes 60° and 30° and longitude 5° W and 30° E, drafted on basis of more than 1000N-values computed at the corners of 1°×1° squares. It is interesting to realize that the geoid undulations in all this area are positive, the extreme values being between 40 and 50 meters. The geophysical significance of the geoid maps of this kind is pointed out.