Towards a direct collapse–load method of design for concrete frames subjected to severe ground motions     

M. C. Griffith  A. Kawano  R. F. Warner 《地震工程与结构动力学》2002,31(10):1879-1888

Most current methods of design for concrete structures under earthquake loads rely on highly idealized ‘equivalent’ static representations of the seismic loads and linear‐elastic methods of structural analysis. With the continuing development of non‐linear methods of dynamic analysis for the overload behaviour and collapse of complete concrete structures, a more direct and more accurate design procedure becomes possible which considers conditions at system collapse. This paper describes an evaluation procedure that uses non‐linear dynamic collapse–load analysis together with global safety coefficients. A back‐calibration procedure for evaluating the global safety coefficients is also described. The aim of this paper is to open up discussion of alternative methods of design with improved accuracy which are necessary to move towards a direct collapse–load method of design. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

Study on effects of damping in laminated rubber bearings on seismic responses for a ⅛ scale isolated test structure     

Bong Yoo  Yang‐Hann Kim 《地震工程与结构动力学》2002,31(10):1777-1792

The effects of damping in various laminated rubber bearings (LRB) on the seismic response of a ?‐scale isolated test structure are investigated by shaking table tests and seismic response analyses. A series of shaking table tests of the structure were performed for a fixed base design and for a base isolation design. Two different types of LRB were used: natural rubber bearings (NRB) and lead rubber bearings (LLRB). Three different designs for the LLRB were tested; each design had a different diameter of lead plug, and thus, different damping values. Artificial time histories of peak ground acceleration 0.4g were used in both the tests and the analyses. In both shaking table tests and analyses, as expected, the acceleration responses of the seismically isolated test structure were considerably reduced. However, the shear displacement at the isolators was increased. To reduce the shear displacement in the isolators, the diameter of the lead plug in the LLRB had to be enlarged to increase isolator damping by more than 24%. This caused the isolator stiffness to increase, and resulted in amplifying the floor acceleration response spectra of the isolated test structure in the higher frequency ranges with a monotonic reduction of isolator shear displacement. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

Approximate analysis methods for asymmetric plan base‐isolated buildings     

Keri L. Ryan  Anil K. Chopra 《地震工程与结构动力学》2002,31(1):33-54

An approximate method for linear analysis of asymmetric‐plan, multistorey buildings is specialized for a single‐storey, base‐isolated structure. To find the mode shapes of the torsionally coupled system, the Rayleigh–Ritz procedure is applied using the torsionally uncoupled modes as Ritz vectors. This approach reduces to analysis of two single‐storey systems, each with vibration properties and eccentricities (labelled ‘effective eccentricities’) similar to corresponding properties of the isolation system or the fixed‐base structure. With certain assumptions, the vibration properties of the coupled system can be expressed explicitly in terms of these single‐storey system properties. Three different methods are developed: the first is a direct application of the Rayleigh–Ritz procedure; the second and third use simplifications for the effective eccentricities, assuming a relatively stiff superstructure. The accuracy of these proposed methods and the rigid structure method in determining responses are assessed for a range of system parameters including eccentricity and structure flexibility. For a subset of systems with equal isolation and structural eccentricities, two of the methods are exact and the third is sufficiently accurate; all three are preferred to the rigid structure method. For systems with zero isolation eccentricity, however, all approximate methods considered are inconsistent and should be applied with caution, only to systems with small structural eccentricities or stiff structures. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

柴达木北缘中生代盆地的成因类型及构造沉积演化   总被引：12，自引：0，他引：12  

和钟铧  刘招君  郭巍  董清水 《吉林大学学报(地球科学版)》2002,32(4):333-339

柴达木盆地是我国西部一个大型中新生代陆相含油气盆地。其剖面结构、构造样式、沉积特征、基底沉降、古地温等表明中生代盆地的性质应为挤压环境下经过多次幕式逆冲形成的、也祁连造山带有关的叠置前陆盆地，经历了早株罗世的破裂前陆盆地和中株罗世之后的类前陆盆地的演化过程。柴达缘中生代沉积充填由构造层序I（早株罗世）、构造层序Ⅱ（中侏罗世）和构造层序Ⅲ（晚侏罗世）三个完整的构造层序构成，由粗到细多个沉积旋回代表了逆冲加载过程中由活动期到平静期的转化过程。随着逆冲活动的加强和频率加快，构造层序Ⅳ（白垩纪）只经历逆冲活动期，是不完整的构造层序，发育补偿和过补偿沉积，盆地逐渐萎缩。  相似文献   

洛带气田蓬莱镇气藏开发部署优化研究     

张箭 《矿物岩石》2002,22(4):83-86

气藏评价尚未结束之前，开发的早期部署工作非常困难。针对洛带气田蓬莱镇组气藏的开发部署工作，利用目前许多新方法对开发层系划分、采气规模、开发规划、合理配产和井网部署等进行了优化研究，对气藏开发提出了指导性意见，且对类似气藏也具有参考意义。  相似文献   

中国煤系高岭岩(土)资源成矿机理与开发利用   总被引：9，自引：0，他引：9  

刘钦甫  杨晓杰  张鹏飞  卞建玲 《矿物学报》2002,22(4):359-364

中国含煤地层中高岭岩（土）分布广泛，成矿时代多，成因复杂，储量丰富，质地优良，是一种重要的自然资源和非金属矿产，具有极高的开发利用价值，在全世界独具特色。本文研究了中国煤系高岭岩（土）资源概况、研究简史；根据成分、结构、地质产状等特征，提出了中国煤系高岭岩（土）的成因类型；对生物和有机质在其形成中的作用进行了分析和探讨，并结合有机酸溶解矿物模拟实验对其成矿作用做了初步探索；最后对煤系高岭岩的某些关键性加工技术进行了简述。  相似文献   

机械研磨对平鲁煤系高岭石热行为的影响     

丁述理  彭苏萍  刘钦甫  许红亮 《煤田地质与勘探》2002,30(6):16-18

对煤系高岭石进行0-2h的研磨之后，再在900℃、1000℃、1400℃的温度条件下分别对其加热1h，然后利用X射线衍射（XRD）、差热分析（DTA）、红外光谱（IR）等手段，研究机械研磨对于煤系高岭石晶体结构的破坏作用以及对其热行为的影响。结果显示，煤系高岭石被研磨1h之后，高岭石的晶体结构几乎全部跨塌。把研磨1h的煤系高岭石加热到1000℃（加热1h），便能形成结晶良好的莫来石。  相似文献   

Division of Gas Accumulation System and Laws Controlling Distribution of Natural Gas in Typical Petroliferous Basins of China     

JIANG Zhenxue  Pang Xiongqi  Jin Zhijun  Chen Dongxia 《中国地质大学学报(英文版)》2002,13(4)

Considering the existing problems of the petroleum system, this paper brings forward the concept of natural gas accumulation system and presents the dividing principles. Then detailed statistics on the accumulation factors of the 32 typical natural gas accumulation systems in China and studies on the laws controlling distribution of gas are collected. The research shows that the petroleum accumulation system is the basic unit controlling petroleum generation, migration and accumulation. Generating intensity, generating amount, accumulating efficiency and migration distance plays an important role in the distribution of natural gas. Through analysis on results of resources evaluation, discovered reserves and residual reserves, potential areas in middle-scaled petroliferous basins in China are forecasted in this paper. Ordos, Sichuan, Tarim and Qaidam basins are found out to be the main basins developing and enriching gas accumulation systems.  相似文献   

The Migif–Hafafit gneissic complex of the Egyptian Eastern Desert: fold interference patterns involving multiply deformed sheath folds     

Abdel-Rahman Fowler  Baher El Kalioubi 《Tectonophysics》2002,346(3-4)

The Wadi Hafafit Complex (WHC) is an arcuate belt of orthogneisses, migmatites and other high-grade metamorphic rocks, which marks the boundary between the Central Eastern and the South Eastern Deserts of Egypt. In the WHC, gneissic meta-gabbro outlines macroscopic fold interference patterns characterized by elliptical to irregular culminations cored by gneissic meta-tonalite to meta-trondhjemite. The five main culminations of the WHC have previously been labeled A (most northerly), B, C, D and E (most southerly). A detailed structural investigation of B, C, D and E reveals that these structures are a result of the interference of four macroscopic fold phases, the first three of which may represent a single deformation event. The first folding involved sheath-like fold nappes, which were transported to the N or NW, assisted by translation on gently dipping mylonite zones. The regional gneissosity and mineral extension lineations formed during this folding event. The fold nappes were deformed by mainly open upright small macroscopic and mesocopic folds with approximately NE-trending hinges. As a probable continuation of the latter folding, the sheaths were buckled into large macroscopic folds and monoclines with the same NE-trends. The fourth macroscopic folding resulted from shortening along the NE–SW direction, producing mainly NW–SE-trending upright gently plunging folds. Gravitative uplift is disputed as a component of the deformation history of the WHC. The peculiarities of the fold interference pattern result from the interesting behaviour of sheath folds during their refolding.  相似文献   

Rate of strike-slip motion on the Amanos Fault (Karasu Valley, southern Turkey) constrained by K–Ar dating and geochemical analysis of Quaternary basalts     

Sema Yurtmen  Herv Guillou  Rob Westaway  George Rowbotham  Orhan Tatar 《Tectonophysics》2002,344(3-4)

The left-lateral Amanos Fault follows a 200-km-long and up to 2-km-high escarpment that bounds the eastern margin of the Amanos mountain range and the western margin of the Karasu Valley in southern Turkey, just east of the northeastern corner of the Mediterranean Sea. Regional kinematic models have reached diverse conclusions as to the role of this fault in accommodating relative motion between either the African and Arabian, Turkish and African, or Turkish and Arabian plates. Local studies have tried to estimate its slip rate by K–Ar dating Quaternary basalts that erupted within the Amanos Mountains, flowed across it into the Karasu Valley, and have since become offset. However, these studies have yielded a wide range of results, ranging from 0.3 to 15 mm a⁻¹, which do not allow the overall role and significance of this fault in accommodating crustal deformation to be determined. We have used the Cassignol K–Ar method to date nine Quaternary basalt samples from the vicinity of the southern part of the Amanos Fault. These basalts exhibit a diverse chemistry, which we interpret as a consequence varying degrees of partial melting of their source combined with variable crustal contamination. This dating allows us to constrain the Quaternary slip rate on the Amanos fault to 1.0 to 1.6 mm a⁻¹. The dramatic discrepancies between past estimates of this slip rate are partly due to technical difficulties in K–Ar dating of young basalts by isotope dilution. In addition, previous studies at the key locality of Hacılar have unwittingly dated different, chemically distinct, flow units of different ages that are juxtaposed. This low slip rate indicates that, at present, the Amanos Fault takes up a small proportion of the relative motion between the African and Arabian plates, which is transferred southward to the Dead Sea Fault Zone. It also provides strong evidence against the long-standing view that its slip continues offshore to the southwest along a hypothetical left-lateral fault zone located south of Cyprus.  相似文献